@article{oliveira_mazzafera_faleiro_mayer_hesterberg_pérez_andrade_2024, title={Tissue-level distribution and speciation of foliar manganese in Eucalyptus tereticornis by µ-SXRF and µ-XANES shed light on its detoxification mechanisms}, url={https://doi.org/10.1016/j.jhazmat.2023.132555}, DOI={10.1016/j.jhazmat.2023.132555}, abstractNote={This study is the first to investigate the speciation and spatial distribution patterns of manganese (Mn) accumulated at elevated concentrations in Eucalyptus leaves by X-ray fluorescence (µ-XRF) and absorption near-edge spectroscopy (µ-XANES). Eucalyptus tereticornis is a tree species with great economic value and potential to accumulate and tolerate high Mn despite not being considered a hyperaccumulator. Seedlings grown under glasshouse conditions were irrigated with two Mn treatments: control Mn (9 µM) and high Mn solution (1000 µM). Biomass and total nutrient concentrations were assessed in roots, stems and leaves. Manganese, calcium (Ca) and potassium (K) spatial patterns were imaged by µ-SXRF in different foliar structures, and Mn speciation was conducted in these compartments by µ-XANES. Under high supply, Mn was distributed across the leaf mesophyll suggesting vacuolar sequestration in these cells. High Mn decreased cytosolic Ca by almost 50% in mesophyll cells, but K remained unaltered. Speciation suggests that a majority of the Mn fraction was complexed by organic ligands modeled as Mn-bound malate and citrate, instead of as free aqueous Mn2+ or oxidised forms. These two detoxification mechanisms: effective vacuolar sequestration and organic acid complexation, may be responsible for the impressively high Mn tolerance found in eucalypts.}, journal={Journal of Hazardous Materials}, author={Oliveira, Vinicius H. De and Mazzafera, Paulo and Faleiro, Rodrigo and Mayer, Juliana Lischka Sampaio and Hesterberg, Dean and Pérez, Carlos Alberto and Andrade, Sara Adrián L.}, year={2024}, month={Jan} }
 @article{gomes_soares_carvalho_sharma_hesterberg_alleoni_2023, title={Zinc speciation and desorption kinetics in a mining waste impacted tropical soil amended with phosphate}, volume={864}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2022.161009}, abstractNote={Mining is an important component of the Brazilian economy. However, it may also contribute to environmental problems such as the pollution of soils with zinc and other potentially toxic metals. Our objective was to evaluate changes in the chemical speciation and mobility of Zn in a soil amended with phosphate. Soil samples were collected from a deactivated mining area in the state of Minas Gerais, Brazil, and amended with NH4H2PO4 saturated with deionized water to 70 % of maximum water retention and incubated at 25 ± 2 °C in open containers for 60 days. The soil was chemically and mineralogically characterized, and sequential extraction, desorption kinetics, and speciation were carried out using synchrotron bulk-sample and micro-X-ray Absorption Near-Edge Structure (XANES/μ-XANES) spectroscopy at the Zn K-edge, and X-ray fluorescence microprobe analysis (μ-XRF). The combination of μ-XRF and μ-XANES techniques made it possible to identify Zn hotspots in the main species formed after phosphate remediation. The best fit combination for bulk XANES and μ-XANES was observed in Zn-montmorillonite, Zn-kerolite, Zn-ferrihydrite, and gahnite. In the course of phosphate treatment, gahnite, Zn layered double hydroxides (Zn-LDH), Zn3(PO4), and ZnO were identified by bulk XANES, while Zn-ferrihydrite, Zn-montmorillonite, and scholzite were identified by μ-XANES. Zinc in the phosphate-amended soil had the strongest partial correlations (r' > 0.05) with Ni, Co, Fe, Cr, Mn, Si, P, Cd, Pb, and Cd, while the unamended soil showed the strongest correlation with Cu, Pb, Fe, and Si. The application of NH4H2PO4 altered Zn speciation and favored an increase in Zn desorption. The most available Zn contents after phosphate amendment were correlated with the release of exchangeable Zn fractions, associated with carbonate and organic matter.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Gomes, Frederico Prestes and Soares, Matheus Bortolanza and Carvalho, Hudson Wallace Pereira and Sharma, Aakriti and Hesterberg, Dean and Alleoni, Luis Reynaldo Ferracciu}, year={2023}, month={Mar} }
 @article{sharma_guinness_muyskens_polizzotto_fuentes_hesterberg_2022, title={<p>Spatial statistical modeling of arsenic accumulation in microsites of diverse soils</p>}, volume={411}, ISSN={["1872-6259"]}, DOI={10.1016/j.geoderma.2022.115697}, abstractNote={Determining reaction mechanisms that control the mobility of nutrients and toxic elements in soil matrices is confounded by complex assemblages of minerals, non-crystalline solids, organic matter, and biota. Our objective was to infer the chemical elements and solids that contribute to As binding in matrices of soil samples from different pedogenic environments at the micrometer spatial scale. Arsenic was reacted with and imaged in thin weathering coatings on eight quartz sand grains separated from soils of different drainage classes to vary contents of Fe and Al (hydr)oxides, organic carbon (OC), and other elements. The grains were analyzed using X-ray fluorescence microprobe (µ-XRF) imaging and microscale X-ray absorption near edge structure (μ-XANES) spectroscopy before and after treatment with 0.1 mM As(V) solution. Partial correlation analyses and regression models developed from multi-element µ-XRF signals collected across 100 × 100 µm2 areas of sand-grain coatings inferred augmenting effects of Fe, Zn, Ti, Mn, or Cu on As retention. Significant partial correlations (r′ > 0.11) between Fe and Al from time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis of most samples suggested that Fe and Al (hydr)oxides were partially co-localized at the microscale. Linear combination fitting (LCF) results for As K-edge μ-XANES spectra collected across grain coatings typically included >80% of As(V) adsorbed on goethite, along with varying proportions of standards of As(V) adsorbed on boehmite, As(V) or As(III) bound to Fe(III)-treated peat, and dimethylarsinic acid. Complementary fits for Fe K-edge μ-XANES spectra included ≥50% of the Fe(III)-treated peat standard for all samples, along with goethite. Our collective results inferred a dominance of Fe and possibly Al (hydr)oxides in controlling As immobilization, with variable contributions from Zn, Ti, Cu, or Mn, both across the coating of a single sand grain and between grains from soils developed under different pedogenic environments. Overall, these results highlight the extreme heterogeneity of soils on the microscale and have implications on soil management for mitigating the adverse environmental impacts of As.}, journal={GEODERMA}, author={Sharma, Aakriti and Guinness, Joseph and Muyskens, Amanda and Polizzotto, Matthew L. and Fuentes, Montserrat and Hesterberg, Dean}, year={2022}, month={Apr} }
 @article{zhi_paterson_call_jones_hesterberg_duckworth_poitras_knappe_2022, title={Mechanisms of orthophosphate removal from water by lanthanum carbonate and other lanthanum-containing materials}, volume={820}, ISSN={["1879-1026"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85123356200&partnerID=MN8TOARS}, DOI={10.1016/j.scitotenv.2022.153153}, abstractNote={Removing phosphorus (P) from water and wastewater is essential for preventing eutrophication and protecting environmental quality. Lanthanum [La(III)]-containing materials can effectively and selectively remove orthophosphate (PO4) from aqueous systems, but there remains a need to better understand the underlying mechanism of PO4 removal. Our objectives were to 1) identify the mechanism of PO4 removal by La-containing materials and 2) evaluate the ability of a new material, La2(CO3)3(s), to remove PO4 from different aqueous matrices, including municipal wastewater. We determined the dominant mechanism of PO4 removal by comparing geochemical simulations with equilibrium data from batch experiments and analyzing reaction products by X-ray diffraction and scanning transmission electron microscopy with energy dispersive spectroscopy. Geochemical simulations of aqueous systems containing PO4 and La-containing materials predicted that PO4 removal occurs via precipitation of poorly soluble LaPO4(s). Results from batch experiments agreed with those obtained from geochemical simulations, and mineralogical characterization of the reaction products were consistent with PO4 removal occurring primarily by precipitation of LaPO4(s). Between pH 1.5 and 12.9, La2(CO3)3(s) selectively removed PO4 over other anions from different aqueous matrices, including treated wastewater. However, the rate of PO4 removal decreased with increasing solution pH. In comparison to other solids, such as La(OH)3(s), La2(CO3)3(s) exhibits a relatively low solubility, particularly under slightly acidic conditions. Consequently, release of La3+ into the environment can be minimized when La2(CO3)3(s) is deployed for PO4 sequestration.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Zhi, Yue and Paterson, Alisa R. and Call, Douglas F. and Jones, Jacob L. and Hesterberg, Dean and Duckworth, Owen W. and Poitras, Eric P. and Knappe, Detlef R. U.}, year={2022}, month={May} }
 @article{askar_youssef_vadas_hesterberg_amoozegar_chescheir_skaggs_2021, title={DRAINMOD-P: A MODEL FOR SIMULATING PHOSPHORUS DYNAMICS AND TRANSPORT IN DRAINED AGRICULTURAL LANDS: I. MODEL DEVELOPMENT}, volume={64}, ISSN={["2151-0040"]}, DOI={10.13031/trans.14509}, abstractNote={HighlightsDRAINMOD-P has been developed to simulate phosphorus (P) dynamics in drained croplands.Key hydrological and biochemical processes affecting P cycling are represented in the model.The model predicts surface and subsurface P losses as affected by weather, soil, and management factors.Abstract. High phosphorus (P) loads to streams and lakes can promote harmful algae blooms and cause water quality deterioration. Recent research has identified subsurface drainage as an important pathway for the transport of dissolved P from drained croplands to receiving surface water bodies, particularly when macropore flow contributes a considerable portion of the subsurface drainage outflow. Currently, a few models are capable of simulating P dynamics in poorly drained soils with artificial drainage systems. The objective of this study was to develop DRAINMOD-P, a field-scale, process-based model that simulates P cycling and transport in drained croplands. Processes represented in the model include atmospheric deposition, organic and inorganic fertilizer applications, plant uptake, sediment-bound and dissolved P losses in both surface runoff and subsurface drainage, tillage practices, and P mineralization and immobilization. The model predicts P losses under different management practices, climatic conditions, drainage systems, and crop rotations. The model is an extension to the nitrogen model DRAINMOD-NII, with full integration of the nitrogen and P model components. DRAINMOD-P uses the recently modified hydrology component that simulates macropore flow. A soil erosion component, based on the RUSLE approach, has been incorporated into the model to estimate sediment loss and associated particulate P loss. Sediment deposition in tile drains is considered to quantify particulate P settling in the drainage system. In this article, we review the approaches used in DRAINMOD-P for simulating P-related processes. Model testing against field-measured data from a subsurface-drained field in northwest Ohio is presented in a companion article. Keywords: Best management practices, Phosphorus model, Phosphorus processes, Soil erosion, Water quality modeling.}, number={6}, journal={TRANSACTIONS OF THE ASABE}, author={Askar, Manal H. and Youssef, Mohamed A. and Vadas, Peter A. and Hesterberg, Dean L. and Amoozegar, Aziz and Chescheir, George M. and Skaggs, R. Wayne}, year={2021}, pages={1835–1847} }
 @article{askar_youssef_hesterberg_king_amoozegar_skaggs_chescheir_ghane_2021, title={DRAINMOD-P: A MODEL FOR SIMULATING PHOSPHORUS DYNAMICS AND TRANSPORT IN DRAINED AGRICULTURAL LANDS: II. MODEL TESTING}, volume={64}, ISSN={["2151-0040"]}, DOI={10.13031/trans.14510}, abstractNote={HighlightsDRAINMOD-P was tested using a dataset from a drained field with desiccation cracks.Surface and subsurface phosphorus losses were mainly in the particulate form.Surface runoff was a major pathway for phosphorus loss in this field.The model performance in predicting edge-of-field phosphorus loss is promising.Abstract. The recently developed phosphorus (P) model DRAINMOD-P was tested using a four-year dataset from a subsurface-drained field in northwest Ohio with significant potential for desiccation cracking or preferential flow. The model satisfactorily predicted subsurface drainage discharge, with a monthly Nash-Sutcliffe efficiency (NSE) of 0.59 and index of agreement (IOA) of 0.89. Lack of annual water budget closure was reported and was likely caused by uncertainty in measured surface runoff and/or modeling approaches representing macropore flow. More than 80% of predicted surface and subsurface P losses were in the particulate form. Surface runoff was the major pathway for P loss, contributing 78% of predicted total P (TP) load. On average, predicted macropore flow represented about 15% of drainage discharge and contributed 21% of DRP loss via subsurface drains. The performance of DRAINMOD-P in predicting monthly dissolved reactive P and TP losses through subsurface drains can be rated as poor (NSE = 0.33 and IOA = 0.60) and very good (NSE = 0.81 and IOA = 0.95), respectively. DRAINMOD-P demonstrated potential for simulating P fate and transport in drained cropland. More testing is needed to further examine newly incorporated hydrological and biogeochemical components of the model. Keywords: Agricultural drainage, Edge-of-field phosphorus load, Macropore flow, Phosphorus model, Sediment yield, Water quality modeling.}, number={6}, journal={TRANSACTIONS OF THE ASABE}, author={Askar, Manal H. and Youssef, Mohamed A. and Hesterberg, Dean L. and King, Kevin W. and Amoozegar, Aziz and Skaggs, R. Wayne and Chescheir, George M. and Ghane, Ehsan}, year={2021}, pages={1849–1866} }
 @article{nascimento_hesterberg_tappero_2021, title={Imaging Zn and Ni distributions in leaves of different ages of the hyperaccumulator Noccaea caerulescens by synchrotron-based X-ray fluorescence}, volume={408}, ISSN={["1873-3336"]}, DOI={10.1016/j.jhazmat.2020.124813}, abstractNote={Mapping of leaves of hyperaccumulators can provide insights into the mechanisms these species utilize to accumulate high metal concentrations. We used synchrotron-based X-ray fluorescence (SXRF) to perform Zn and Ni imaging in leaves of different ages of Noccaea caerulescens. A mature leaf of the related non-hyperaccumulator Thlaspi arvense was also imaged. The concentrations of Zn, Ni, Co, and Cr in N. caerulescens grown on an ultramafic soil were 9-, 10-, 12-, and 3-fold higher than T. arvense. N. caerulescens showed an exceptional ability to accumulate Zn from the soil, posing a bioconcentration factor of 6.7. T. arvense had Zn and Ni distributed uniformly in the leaf blade with doubling fluorescence counts in the tip and margins, suggesting a strategy to excrete metals and avoid toxicity. On the other hand, N. caerulescens displayed distinctly different Zn and Ni accumulation patterns, regardless of the age or metal concentration in the leaves. Zinc was mainly distributed in the cells surrounding the central and secondary veins. Nickel accumulated in the margins and tips of the leaf blade. Given the time required to image large leaves in synchrotron facilities, small leaves can be used to represent the leaf distribution of Zn and Ni in N. caerulescens.}, journal={JOURNAL OF HAZARDOUS MATERIALS}, author={Nascimento, Clistenes Williams and Hesterberg, Dean and Tappero, Ryan}, year={2021}, month={Apr} }
 @article{yamaguchi_ohkura_hikono_hashimoto_suda_yamamoto_ando_kasuya_northrup_wang_et al._2021, title={Microscale Heterogeneous Distribution and Speciation of Phosphorus in Soils Amended with Mineral Fertilizer and Cattle Manure Compost}, volume={11}, ISSN={["2075-163X"]}, DOI={10.3390/min11020121}, abstractNote={Global concerns for the sustainability of agriculture have emphasized the need to reduce the use of mineral fertilizer. Although phosphorus (P) is accumulated in farmland soils due to the long-term application of fertilizer, most soil P is not readily available to plants. The chemical speciation of P in soils, which comprise heterogeneous microenvironments, cannot be evaluated with a high degree of specificity using only macroscopic analyses. In this study, we investigated the distribution and speciation of P accumulated in soils by using both macro- and microscopic techniques including chemical extraction, solution and solid-state 31P NMR, bulk- and micro- P K-edge X-ray absorption near edge structure (XANES), and electron probe microanalysis (EPMA). Soil samples were collected from a field in which cabbage was cultivated under three amendment treatments: i) mineral fertilizer (NPK), ii) mineral fertilizer and compost (NPK + compost), and iii) mineral fertilizer plus compost but without nitrogen fertilizer (PK + compost). Macro-scale analyses suggested that accumulated P was predominantly inorganic P and associated with Al-bearing minerals. The repeated application of compost to the soils increased the proportion of P associated with Ca which accounted for 17% in the NPK + compost plot and 40% in the PK + compost plot. At the microscale, hot spots of P were heterogeneously distributed, and P was associated with Fe and Ca in hot spots of the NPK + compost (pH 6) and PK + compost (pH 7) treated samples, respectively. Our results indicate that application of compost contributed to creating diverse microenvironments hosting P in these soils.}, number={2}, journal={MINERALS}, author={Yamaguchi, Noriko and Ohkura, Toshiaki and Hikono, Atsuko and Hashimoto, Yohey and Suda, Aomi and Yamamoto, Taku and Ando, Kaori and Kasuya, Masahiro and Northrup, Paul and Wang, Shan-Li and et al.}, year={2021}, month={Feb} }
 @article{dela piccolla_hesterberg_muraoka_novotny_2021, title={Optimizing pyrolysis conditions for recycling pig bones into phosphate fertilizer}, volume={131}, ISSN={["1879-2456"]}, DOI={10.1016/j.wasman.2021.06.012}, abstractNote={Selecting pyrolysis parameters for recycling P-rich and hazardous biowastes, such as bones, into fertilizers is still a challenge. Our objective was to improve pyrolysis procedures of pig bones for the production of P fertilizers. Bone chars were produced by pyrolysis at 400, 550, or 800 °C with no gas addition; 550 and 800 °C under N2; 800 °C under steam flux, using calcination at 800 °C as control treatment. Synchrotron-based X-ray diffraction and X-ray absorption near edge structure spectroscopy at the P and Ca K- and L-edges showed that these bone chars were largely composed of hydroxyapatite. Hydroxyapatite crystallization was inhibited by pyrolysis conducted in the absence of oxygen at 400, 550, or 800 °C, either under no gas or under N2 flux. The clogging of pores by lack of organic compounds removal was hypothesized to cause low surface area of 400 °C bone char, resulting in a fertilizer with citric-acid soluble P as low as calcination, while 550 and 800 °C bone chars obtained in absence of oxygen showed greater porosity, surface area, and citric acid-soluble P than steamed or calcined samples at 800 °C. Although extractable phosphate in water and neutral-ammonium-citrate showed trends comparable to those from citric acid, it was negligible for all heated materials. Since it is possible to produce bone chars with different chemical, physical and crystallographic properties by managing pyrolysis conditions, bone chars can be designed to increase their suitability as P fertilizers for different purposes, such as high solubility or slow P release.}, journal={WASTE MANAGEMENT}, author={Dela Piccolla, Cristiano and Hesterberg, Dean and Muraoka, Takashi and Novotny, Etelvino Henrique}, year={2021}, month={Jul}, pages={249–257} }
 @article{novais alves_ortega rodriguez_rocha_vergutz_santini junior_hesterberg_ruiz pessenda_tomazello-filho_costa_2021, title={Synchrotron-based X-ray microscopy for assessing elements distribution and speciation in mangrove tree-rings}, volume={3}, ISSN={["2211-7156"]}, DOI={10.1016/j.rechem.2021.100121}, abstractNote={Micro-X-ray fluorescence (μ-XRF) spectroscopy has been used for dendrochemistry as a high spatial resolution, multi-elemental and non-destructive technique. Furthermore, micro-X-ray absorption near edge structure (μ-XANES) spectroscopy has a potential application in environmental studies by adding speciation information under in-situ conditions. Both, μ-XRF and μ-XANES, techniques were used to assess the inter-ring and intra-ring chemical content variations of Avicennia schaueria mangrove tree from Southeastern Brazil. Ca, Cl, K, P, and S were the major chemical elements distributed in almost all tree-rings. Ca was the most abundant element and showed a decreasing trend from heartwood to sapwood tree-rings. Calcium also showed a characteristic distribution pattern along the growth layer, acting as a chemical marker of growth layers. Ca chemical species were distinct in sapwood (calcium oxalate and carbonate-rich) and heartwood tree-rings (calcium sulfate-rich), showing different physiological Ca roles on tree performance. The synchrotron radiation-based techniques at micrometer scale provided information on the distribution and speciation of chemical elements within and between tree-rings. We also present a µ-XANES procedure for data collection and processing for dendrochemical studies. Altogether, we opened opportunities for further studies aiming to understand which environmental or physiological variables are responsible for tree-ring chemical speciation and distribution changes in tree species.}, journal={RESULTS IN CHEMISTRY}, author={Novais Alves, Elton Eduardo and Ortega Rodriguez, Daigard Ricardo and Rocha, Pablo de Azevedo and Vergutz, Leonardus and Santini Junior, Luiz and Hesterberg, Dean and Ruiz Pessenda, Luiz Carlos and Tomazello-Filho, Mario and Costa, Liovando Marciano}, year={2021}, month={Jan} }
 @article{gustafsson_braun_tuyishime_adediran_warrinnier_hesterberg_2020, title={A Probabilistic Approach to Phosphorus Speciation of Soils Using P K-edge XANES Spectroscopy with Linear Combination Fitting}, volume={4}, ISSN={["2571-8789"]}, DOI={10.3390/soilsystems4020026}, abstractNote={A common technique to quantitatively estimate P speciation in soil samples is to apply linear combination fitting (LCF) to normalized P K-edge X-ray absorption near-edge structure (XANES) spectra. Despite the rapid growth of such applications, the uncertainties of the fitted weights are still poorly known. Further, there are few reports to what extent the LCF standards represent unique end-members. Here, the co-variance between 34 standards was determined and their significance for LCF was discussed. We present a probabilistic approach for refining the calculation of LCF weights based on Latin hypercube sampling of normalized XANES spectra, where the contributions of energy calibration and normalization to fit uncertainty were considered. Many of the LCF standards, particularly within the same standard groups, were strongly correlated. This supports an approach in which the LCF standards are grouped. Moreover, adsorbed phytates and monetite were well described by other standards, which puts into question their use as end-members in LCF. Use of the probabilistic method resulted in uncertainties ranging from 2 to 11 percentage units. Uncertainties in the calibrated energy were important for the LCF weights, particularly for organic P, which changed with up to 2.7 percentage units per 0.01 eV error in energy. These results highlight the necessity of careful energy calibration and the use of frequent calibration checks. The probabilistic approach, in which at least 100 spectral variants are analyzed, improves our ability to identify the most likely P compounds present in a soil sample, and a procedure for this is suggested in the paper.}, number={2}, journal={SOIL SYSTEMS}, author={Gustafsson, Jon Petter and Braun, Sabina and Tuyishime, J. R. Marius and Adediran, Gbotemi A. and Warrinnier, Ruben and Hesterberg, Dean}, year={2020}, month={Jun} }
 @article{nascimento_hesterberg_tappero_nicholas_silva_2020, title={Citric acid-assisted accumulation of Ni and other metals by Odontarrhena muralis: Implications for phytoextraction and metal foliar distribution assessed by mu-SXRF}, volume={260}, ISSN={["1873-6424"]}, DOI={10.1016/j.envpol.2020.114025}, abstractNote={Odontarrhena muralis is one of the most promissing plant species for Ni phytomining, and soil amendments can further increase its Ni phytoextraction ability. Here we investigated whether Ni phytomining/phytoremediation using this Ni hyperaccumulator can benefit from applying citric acid to a serpentine soil that is naturally enriched in Ni (>1000 mg kg-1). Synchrotron micro X-ray fluorescence (μ-SXRF) was used to image Ni and other metal distributions in whole fresh leaves of O. muralis. Leaf Ni accumulation in plants grown on citric acid-amended soil increased up to 55% while Co, Cr, Fe, Mn, and Zn concentrations were 4-, 14-, 6-, 7- and 1.3-fold higher than the control treatment. O. muralis presented high bioconcentration factors (leaf to soil concentration ratio) to Ni and Zn whereas Cr was seemingly excluded from uptake. The μ-SXRF images showed a uniform distribution of Ni, preferential localization of Co in the leaf tip, and clear concentration of Mn in the base of trichomes. The citric acid treatments strongly increased the Co fluoerescence intensity in the leaf tip and altered the spatial distribution of Mn across the leaf, but there was no difference in Ni fluorescence counts between the trichome-base region and the bulk leaf. Our data from a serpentine soil suggests that citrate treatment enhances Ni uptake, but Co is excreted from leaves even in low leaf concentrations, which can make Co phytoming using O. muralis unfeasible in natural serpentine soils.}, journal={ENVIRONMENTAL POLLUTION}, author={Nascimento, Clistenes Williams and Hesterberg, Dean and Tappero, Ryan and Nicholas, Sarah and Silva, Fernando Bruno}, year={2020}, month={May} }
 @article{askar_youssef_chescheir_negm_king_hesterberg_amoozegar_skaggs_2020, title={DRAINMOD Simulation of macropore flow at subsurface drained agricultural fields: Model modification and field testing}, volume={242}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2020.106401}, abstractNote={Macropores are critical pathways through which water and pollutants can bypass the soil matrix and be rapidly transported to subsurface drains and freshwater bodies. We modified the DRAINMOD model to simulate macropore flow using a simple approach as part of developing the DRAINMOD-P model to simulate phosphorus dynamics in artificially drained agricultural lands. The Hagen-Poiseuille’s law was used to estimate the flow capacity of macropores. When ponding depths on the soil surface are greater than Kirkham’s depth, water is assumed to flow through macropores directly to tile drains without interaction with the soil matrix. In the modified model, macropore size is adjusted based on wet or dry conditions while connectivity is altered by tillage. The model was tested using a 4-year data set from a subsurface drained field in northwest Ohio. The soils at the field are classified as very poorly drained and are prone to desiccation cracking. The modified model predicted the daily and monthly subsurface drainage with average Nash-Sutcliffe efficiency (NSE) values of 0.48 and 0.59, respectively. The cumulative drainage over the 4-year simulation period was under-predicted by 8%. The new macropore component was able to capture about 75% of 60 peak drainage flow events. However, surface runoff was over-predicted for the entire study period. Annual water budgets using measured data (precipitation, subsurface drainage, and surface runoff) and model predictions (evapotranspiration, vertical seepage, and change in storage) were not balanced with an average annual imbalance of 6.4 cm. The lack of closure in the water balance suggests that errors may have occurred in field measurements, particularly, surface runoff. Overall, incorporating macropore flow into DRAINMOD improved predictions of daily drainage peaks and enabled the model to predict subsurface drainage flux contributed by macropore flow, which is critical for expanding DRAINMOD to simulate phosphorus transport in subsurface drained agricultural land.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Askar, Manal H. and Youssef, Mohamed A. and Chescheir, George M. and Negm, Lamyaa M. and King, Kevin W. and Hesterberg, Dean L. and Amoozegar, Aziz and Skaggs, R. Wayne}, year={2020}, month={Dec} }
 @article{nascimento_hesterberg_tappero_2020, title={Effects of exogenous citric acid on the concentration and spatial distribution of Ni, Zn, Co, Cr, Mn and Fe in leaves of Noccaea caerulescens grown on a serpentine soil}, volume={398}, url={https://doi.org/10.1016/j.jhazmat.2020.122992}, DOI={10.1016/j.jhazmat.2020.122992}, abstractNote={The aim of this study was to show the potential of citric acid in increasing the concentration of Ni, Zn, Co, Cr, Mn and Fe in leaves of the hyperaccumulator Noccaea caerulescens. Synchrotron x-ray fluorescence (μ-XRF) images were collected to assess the distribution of metals in leaves. Applying citric acid (20 mmol kg-1) to soil increased in 14-, 10-, 7-, 2- and 1.4- fold the concentration of Mn, Fe, Co, Ni, and Cr, respectively, compared to the control. The μ-XRF imaging revealed that Ni and Zn were not spatially correlated across the leaf. We observed a clear partitioning of Zn between veins and surrounding leaf cells while Ni was more evenly distributed between veins and leaf blade. The accumulation of metals in citric acid treated plants did not change the Ni and Zn distribution pattern in leaves but altered the Mn distribution. It seems that Mn reached toxic concentrations in leaves and we hypothesize that a mechanism driven by transpiration through the xylem was used to excrete the metal. Our results show that citric acid can enhance metal accumulation by N. caerulescens and have impact for soil remediation by either decreasing the time for clean up or increasing the access to non-labile pools of metals in soil.}, journal={Journal of Hazardous Materials}, publisher={Elsevier BV}, author={Nascimento, Clistenes Williams Araujo and Hesterberg, Dean and Tappero, Ryan}, year={2020}, month={Nov}, pages={122992} }
 @article{doydora_thompson_hesterberg_2020, title={Phosphate solubilization from adsorbents and precipitates by different AVAIL polymers}, volume={84}, ISSN={["1435-0661"]}, DOI={10.1002/saj2.20168}, abstractNote={Abstract Less than 40% of phosphate fertilizer applied to soils is typically taken up by the intended crop within the year of application because of strong soil retention. AVAIL polymers are fertilizer additives that were commercially developed to enhance availability of fertilizer phosphate. Knowledge of underlying mechanisms of phosphate solubilization would help to optimize the effectiveness of these polymers for different soils. This study compared different types and levels of AVAIL polymers in solubilizing (ad)sorbed and precipitated phosphate to gain insights into the mechanisms involved. Varying inputs of four newer forms of polymers and the original AVAIL (Original) were co‐reacted with one level of phosphate (ad)sorbed on ferrihydrite or noncrystalline Al hydroxide in batch (ad)sorption experiments or with Fe and Ca phosphate precipitates in dissolution experiments. Dissolved phosphate increased with increasing levels of co‐added polymers reacted with (ad)sorbents or phosphate precipitates. Across input levels evaluated, the Original AVAIL generally solubilized more phosphate from ferrihydrite than any of the new formulations. The Original and the new Liquid 2 formulation equally solubilized the greatest phosphate from Fe phosphate, whereas Liquid 2 solubilized more phosphate from Al hydroxide and Ca phosphate. (Ad)sorption and dissolution results implied competitive (ad)sorption and complexometric dissolution as key mechanisms. Our results suggest that the effectiveness of AVAIL polymers in soils depends on the level of added polymer charge relative to phosphate adsorption capacities or the types of phosphate minerals present.}, number={6}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Doydora, Sarah and Thompson, Margaret and Hesterberg, Dean}, year={2020}, month={Nov}, pages={1833–1845} }
 @article{sharma_muyskens_guinness_polizzotto_fuentes_tappero_chen-wiegart_thieme_williams_acerbo_et al._2019, title={Multi-element effects on arsenate accumulation in a geochemical matrix determined using mu-XRF, mu-XANES and spatial statistics}, volume={26}, ISSN={["1600-5775"]}, DOI={10.1107/S1600577519012785}, abstractNote={Soils regulate the environmental impacts of trace elements, but direct measurements of reaction mechanisms in these complex, multi-component systems can be challenging. The objective of this work was to develop approaches for assessing effects of co-localized geochemical matrix elements on the accumulation and chemical speciation of arsenate applied to a soil matrix. Synchrotron X-ray fluorescence microprobe (µ-XRF) images collected across 100 µm × 100 µm and 10 µm × 10 µm regions of a naturally weathered soil sand-grain coating before and after treatment with As(V) solution showed strong positive partial correlations (r' = 0.77 and 0.64, respectively) between accumulated As and soil Fe, with weaker partial correlations (r' > 0.1) between As and Ca, and As and Zn in the larger image. Spatial and non-spatial regression models revealed a dominant contribution of Fe and minor contributions of Ca and Ti in predicting accumulated As, depending on the size of the sample area analyzed. Time-of-flight secondary ion mass spectrometry analysis of an area of the sand grain showed a significant correlation (r = 0.51) between Fe and Al, so effects of Fe versus Al (hydr)oxides on accumulated As could not be separated. Fitting results from 25 As K-edge microscale X-ray absorption near-edge structure (µ-XANES) spectra collected across a separate 10 µm × 10 µm region showed ∼60% variation in proportions of Fe(III) and Al(III)-bound As(V) standards, and fits to µ-XANES spectra collected across the 100 µm × 100 µm region were more variable. Consistent with insights from studies on model systems, the results obtained here indicate a dominance of Fe and possibly Al (hydr)oxides in controlling As(V) accumulation within microsites of the soil matrix analyzed, but the analyses inferred minor augmentation from co-localized Ti, Ca and possibly Zn.}, journal={JOURNAL OF SYNCHROTRON RADIATION}, author={Sharma, Aakriti and Muyskens, Amanda and Guinness, Joseph and Polizzotto, Matthew L. and Fuentes, Montserrat and Tappero, Ryan V. and Chen-Wiegart, Yu-chen K. and Thieme, Juergen and Williams, Garth J. and Acerbo, Alvin S. and et al.}, year={2019}, month={Nov}, pages={1967–1979} }
 @article{colocho hurtarte_souza-filho_santos_vergutz_prietzel_hesterberg_2019, title={Optimization of Data Processing Minimizes Impact of Self-Absorption on Phosphorus Speciation Results by P K-Edge XANES}, volume={3}, ISSN={["2571-8789"]}, DOI={10.3390/soilsystems3030061}, abstractNote={Bulk soil phosphorus speciation by X-ray absorption spectroscopy (XAS) using fluorescence yield-mode measurements is an important tool for phosphorus research because of the low soil P contents. However, when measuring in fluorescence mode, increasing the concentration of the absorbing atom can dampen the XAS spectral features because of self-absorption and affect the linear combination (LC) fitting results. To reduce the self-absorption for samples of high P contents, thick boron nitride diluted samples are produced, yet the effects of self-absorption on P speciation results via LC fitting of P K-edge XANES spectroscopy, and the possible benefits of data processing optimization are unknown. Toward this end, we produced a series of ternary standard mixtures (calcium-iron-aluminum phosphates) and an example soil sample both diluted using boron nitride over a range from 1 to ~900 mmol kg−1 for the soil sample and up to ~6000 mmol kg−1 for the standard mixture. We show that by optimizing background subtraction and normalization values, consistent results with less than 10% error can be obtained for samples with up to 300 mmol kg−1 P. Our results highlight the applicability of optimized P K-edge XANES fitting across a wide range of concentrations encountered in natural environments.}, number={3}, journal={SOIL SYSTEMS}, author={Colocho Hurtarte, Luis Carlos and Souza-Filho, Luiz Francisco and Santos, Wedisson Oliveira and Vergutz, Leonardus and Prietzel, Joerg and Hesterberg, Dean}, year={2019}, month={Sep} }
 @misc{hesterberg_2019, title={Response to letter to the editor on synchrotron-based identification of reaction products in phosphorus fertilized alkaline soils}, volume={337}, ISSN={["1872-6259"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85053312168&partnerID=MN8TOARS}, DOI={10.1016/j.geoderma.2018.09.014}, abstractNote={The molecular speciation of phosphorus (P) in forest soils is of strategic importance for sustainable forest management. However, only limited information exists about soil P speciation in boreal forests. We combined P K-edge XANES spectroscopy, wet chemical P extractions, and X-ray diffraction analysis of soil minerals to investigate the vertical distribution of P species in seven podzolised forest soils differing in soil properties and climatic conditions. The results showed that the total P stock was on average, 4.0 g m−2 in the Oe horizon, 9.5 g m−2 in the A and E horizons, and substantially higher (117.5 g m−2, and 109.3 g m−2) in the B and C horizons down to 80 cm depth, respectively. Although the Oe horizons contain a minor total P stock, 87% of it was stored as organic P. The composition of P species in the P-depleted A/E horizons was highly variable depending on the site. However, of the P stored in B and C horizons down to 80 cm, 58% was adsorbed P, mostly to Al, while apatite accounted for 25% of P, most of which was found in the C horizons. The apatite stocks in the A/E, B, and C horizons (down to 80 cm) accounted for 2.5%, 20%, and 77.2%, respectively, of the total apatite for all the mineral soils studied. These figures can be explained, first, by the dissolution of primary mineral apatite caused mainly by acidification. Second, P uptake by plants and microorganisms, and the associated formation of the Oe horizons, led to the formation of soil organic P. Further, the formation of organo-metal complexes and podzolization led to the translocation of P to the B horizons, where P accumulated mostly as P adsorbed to imogolite-type materials (e.g. allophane) and ferrihydrite, as shown by P K-edge XANES spectroscopy. In conclusion, this study shows that despite the young age of these soils (<15,000 years), most of the primary mineral apatite in the upper 30 cm has been transformed into organic P, and Fe-, Al-bound PO4. Moreover, the subsoil P, mainly consisting of adsorbed P to Al, and apatite, dominates the P inventory and probably serves as a long-term buffer of P.}, journal={GEODERMA}, author={Hesterberg, Dean}, year={2019}, month={Mar}, pages={150–151} }
 @article{lebeau_dickey_augustyn_hesterberg_brown_2018, title={Acquisition of a microscope for in situ studies of hard and soft matter}, volume={24}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/S143192761801214X}, DOI={10.1017/S143192761801214X}, abstractNote={,}, number={S1}, journal={Microscopy and Microanalysis}, publisher={Cambridge University Press (CUP)}, author={LeBeau, James M. and Dickey, Elizabeth C. and Augustyn, Veronica and Hesterberg, Dean L. and Brown, Ashley C.}, year={2018}, month={Aug}, pages={2332–2333} }
 @inproceedings{deviney_classen_rice_hesterberg_2018, title={Ammonium ion selective electrode response in swine urine solutions}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85054172161&partnerID=MN8TOARS}, DOI={10.13031/aim.201800208}, abstractNote={<b>Abstract.</b> <b>Global awareness of nitrogen loss from livestock manure is driving research towards reducing ammonia emissions. The majority of manure ammonia is produced by the hydrolysis of urine urea by urease enzyme from fecal bacteria near the time of deposition. Over time, microbial activity produces additional ammonia through the metabolism of organic nitrogen in manure. An immediate and accurate field method would be a useful tool to quantify ammonia formation and loss. Standard colorimetric methods of measuring ammonia typically involve extensive sample preparation and costly equipment. Ammonium ion selective electrodes (AISEs) are a common portable tool used for water quality analysis but little literature exists for their use in manure solutions. Manure solutions contain much higher concentrations of ammonium and other ions than municipal wastewater, resulting in high ionic strength and other potential interferences in an AISE response. A method that corrects for these interferences would enable more rapid measurement of ammonium. Comparison with spectrophotometric lab analysis was used to determine the effect of sow urine on AISE response. Dilutions of sow urine with and without ammonium spikes were used to assess the effect of ionic strength and K:NH<sub>4</sub> ratios on AISE response. Results confirm that ionic strength exerts a suppressive effect while high interfering ion ratios increase the reading. Based on these results, future work may determine how to mitigate the effects of high ionic strength and interfering ion concentrations in manure solutions. This will allow the development of a methodology for determining ammonium concentrations in these solutions.</b>}, booktitle={ASABE 2018 Annual International Meeting}, author={Deviney, A.V. and Classen, J.J. and Rice, J.M. and Hesterberg, D.}, year={2018} }
 @article{terres_fuentes_hesterberg_polizzotto_2018, title={Bayesian Spectral Modeling for Multivariate Spatial Distributions of Elemental Concentrations in Soil}, volume={13}, ISSN={["1936-0975"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85039854529&partnerID=MN8TOARS}, DOI={10.1214/16-ba1034}, abstractNote={Recent technological advances have enabled researchers in a variety of fields to collect accurately geocoded data for several variables simultaneously. In many cases it may be most appropriate to jointly model these multivariate spatial processes without constraints on their conditional relationships. When data have been collected on a regular lattice, the multivariate conditionally autoregressive (MCAR) models are a common choice. However, inference from these MCARmodels relies heavily on the pre-specified neighborhood structure and often assumes a separable covariance structure. Here, we present a multivariate spatial model using a spectral analysis approach that enables inference on the conditional relationships between the variables that does not rely on a pre-specified neighborhood structure, is non-separable, and is computationally efficient. Covariance and crosscovariance functions are defined in the spectral domain to obtain computational efficiency. The resulting pseudo posterior inference on the correlation matrix allows for quantification of the conditional dependencies. A comparison is made with an MCAR model that is shown to be highly sensitive to the choice of neighborhood. The approaches are illustrated for the toxic element arsenic and four other soil elements whose relative concentrations were measured on a microscale spatial lattice. Understanding conditional relationships between arsenic and other soil elements provides insights for mitigating pervasive arsenic poisoning in drinking water in southern Asia and elsewhere.}, number={1}, journal={BAYESIAN ANALYSIS}, author={Terres, Maria A. and Fuentes, Montserrat and Hesterberg, Dean and Polizzotto, Matthew}, year={2018}, month={Mar}, pages={1–28} }
 @article{lopez_silva_webb_hesterberg_buchwalter_2018, title={Periphyton and abiotic factors influencing arsenic speciation in aquatic environments}, volume={37}, ISSN={["1552-8618"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85039735474&partnerID=MN8TOARS}, DOI={10.1002/etc.4025}, abstractNote={Abstract}, number={3}, journal={ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY}, author={Lopez, Adeline R. and Silva, Silmara Costa and Webb, Samuel M. and Hesterberg, Dean and Buchwalter, David B.}, year={2018}, month={Mar}, pages={903–913} }
 @article{rivera_hesterberg_kaur_duckworth_2017, title={Chemical Speciation of Potentially Toxic Trace Metals in Coal Fly Ash Associated with the Kingston Fly Ash Spill}, volume={31}, ISSN={["1520-5029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85029897922&partnerID=MN8TOARS}, DOI={10.1021/acs.energyfuels.7b00020}, abstractNote={Coal ash released into the environment may release toxic trace elements into water, sediments, and soils. The objective of this study was to characterize the chemical speciation of As, Se, Cu, Zn, Cr, and U in coal fly ash samples related to the 2008 Kingston ash spill. Three ash samples were analyzed using X-ray absorption spectroscopy (XAS) to determine oxidation states or dominant species of trace elements, which were previously found to range in concentration from 8 to 20 mg kg–1. Linear combination fitting (LCF) of X-ray absorption near edge structure (XANES) spectra from ash samples indicated that both reduced and oxidized forms of the trace elements were present in the fly ash samples. We used the mineralogical composition of the fly ash to select the most relevant standards for LCF fitting of XANES spectra, which included metal-doped glasses, trace elements sorbed to iron oxy(hydroxides), and pure mineral phases for each element. Arsenic K-edge XANES spectra were best fit as oxidized As(V) (95–100...}, number={9}, journal={ENERGY & FUELS}, author={Rivera, Nelson and Hesterberg, Dean and Kaur, Navdeep and Duckworth, Owen W.}, year={2017}, month={Sep}, pages={9652–9659} }
 @article{li_deng_hesterberg_xia_wu_xu_2017, title={Mechanisms of enhanced inorganic phosphorus accumulation by periphyton in paddy fields as affected by calcium and ferrous ions}, volume={609}, ISSN={["1879-1026"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85026230663&partnerID=MN8TOARS}, DOI={10.1016/j.scitotenv.2017.07.117}, abstractNote={The effect of periphyton propagation in paddy fields on phosphorus biogeochemical cycling has received little attention. In this phytotron study, inorganic phosphorus (Pi) accumulation by periphyton was investigated for varying inputs of calcium [Ca(II)] or ferrous‑iron [Fe(II)], and lighting conditions. Results indicated that additions of Ca(II) or Fe(II) enhanced abiotic accumulation of Pi by up to 16 times, and decreased solution Pi concentration by up to 50%, especially under light condition. The enhanced Pi accumulation into periphyton intensified with increasing Pi concentration, and Pi accumulation showed a positive linear relationship with Ca or Fe accumulation. Abiotic accumulation of Pi induced by Ca(II) was mainly through Ca-phosphate precipitation, and co-precipitation of P with carbonates at pH > 8. Accumulation with added Fe(II) was mainly considered to be through Fe(III) phosphate precipitation coupled with adsorption of Pi by ferric hydroxides. Moreover, Fe(II) was more effective than Ca(II) in promoting abiotic accumulation of Pi by periphyton. Our results indicate the potential for controlling environmental factors to enhance the role of periphyton in biogeochemical cycling and P-use efficiency in paddy rice fields and to reduce P discharged to neighboring water bodies.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Li, Jiu-yu and Deng, Kai-ying and Hesterberg, Dean and Xia, Yong-qiu and Wu, Chen-xi and Xu, Ren-kou}, year={2017}, month={Dec}, pages={466–475} }
 @article{barnes_nelson_hesterberg_shi_whipker_2017, title={Modeling impact of nitrogen carrier and concentration on root substrate pH}, volume={40}, ISSN={["1532-4087"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85029409669&partnerID=MN8TOARS}, DOI={10.1080/01904167.2016.1143502}, abstractNote={ABSTRACT We conducted an experiment to quantify the effects on substrate pH from nitrogen (N) carrier and concentration. We used four concentrations of N (3.5–14 mM) and five fractions of ammonium (NH4+) (0–80% NH4+ of total N) that are found in commercially available fertilizers. Fertilizers were applied to fallow 14-cm-diameter pots (1.29 L) filled with a 3 peat:1 perlite (v/v) substrate amended with non-residual powdered calcium carbonate to raise the substrate pH to approximately 6.0. Harvests occurred at 20 and 42 days. Significant effects in the model included main effects of N carrier and N concentration, their squared terms, an interaction effect, and a time × N carrier. The fraction of NH4+ accounted for 45.0% of variation in substrate pH, and N concentration accounted for 1.5% of the total R2 of 76.7%. Substrate acidification was likely due to the physiological fertilizer effect and nitrification.}, number={15}, journal={JOURNAL OF PLANT NUTRITION}, author={Barnes, Jared and Nelson, Paul V. and Hesterberg, Dean and Shi, Wei and Whipker, Brian E.}, year={2017}, pages={2101–2108} }
 @article{scheibener_rivera_hesterberg_duckworth_buchwalter_2017, title={Periphyton uptake and trophic transfer of coal fly-ash-derived trace elements}, volume={36}, ISSN={["1552-8618"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85024902922&partnerID=MN8TOARS}, DOI={10.1002/etc.3864}, abstractNote={Abstract}, number={11}, journal={ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY}, author={Scheibener, Shane A. and Rivera, Nelson A. and Hesterberg, Dean and Duckworth, Owen W. and Buchwalter, David B.}, year={2017}, month={Nov}, pages={2991–2996} }
 @article{doydora_hesterberg_klysubun_2017, title={Phosphate Solubilization from Poorly Crystalline Iron and Aluminum Hydroxides by AVAIL Copolymer}, volume={81}, ISSN={["1435-0661"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85014520924&partnerID=MN8TOARS}, DOI={10.2136/sssaj2016.08.0247}, abstractNote={
Core Ideas
Dissolved P increased with increasing co‐additions of AVAIL and P to metal oxides.
AVAIL dissolved greater P with Al‐hydroxide than with ferrihydrite.
AVAIL had no effect on P bonding distribution between Al(III) and Fe(III) in mixed sorbents.
Less than 40% of fertilizer phosphate applied to soils is generally taken up by crops because of strong retention of P by soil solids. Our objective was to determine mechanisms by which AVAIL, a maleic‐itaconic copolymer used as a fertilizer additive, potentially affects retention of applied phosphate, and consequently plant availability. We measured competitive sorption of AVAIL and orthophosphate in aqueous suspensions of ferrihydrite and poorly crystalline Al hydroxide [pxl‐Al(OH)3] at pH 6.2, and characterized phosphate bonding distribution between Fe(III) and Al(III) in 1:1 (w/w) mixtures of these solids using P K‐edge X‐ray absorption near edge structure (XANES) spectroscopy. With increasing co‐additions of AVAIL and P at the levels evaluated, sorption results showed dissolved P increasing up to 0.45 and 1.25 mM for ferrihydrite and pxl‐Al(OH)3, respectively, which represented 18 and 34% of added P. Negative relationships between sorbed P and sorbed AVAIL implied a competitive adsorption mechanism between these two ligands, and solubilization of Fe by AVAIL indicated complexometric dissolution of ferrihydrite. The XANES results showed that 72 to 86% of sorbed P was bonded with Al(III) in the ferrihydrite/pxl‐Al(OH)3 mixtures, with only a minor (<15%) effect of AVAIL apparent when P was applied at the two levels tested in this study. Our results suggest that optimized AVAIL application rates for enhancing crop availability of P would depend on soil sorption characteristics and the soil content of residual P relative to its soil sorption capacity.}, number={1}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Doydora, Sarah and Hesterberg, Dean and Klysubun, Wantana}, year={2017}, pages={20–28} }
 @article{santos_hesterberg_alleoni_2017, title={Phosphate Speciation and Citrate-Induced Mobilization of P in an Acric Oxisol}, volume={48}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85038101213&partnerID=MN8TOARS}, DOI={10.1080/00103624.2017.1395450}, abstractNote={ABSTRACT Billions of dollars are spent annually in Brazil on imported phosphorus (P) fertilizers for agricultural crops produced on Oxisols. Phosphate fixation by Oxisols is a main limitation to crop productivity because these highly weathered soils have a high phosphate adsorption capacity. The objective was to determine whether reaction of an Acric Oxisol with citrate increases P availability. Columns of P-amended subsoil material were leached with 1 mM citrate solution, and effluent was monitored. Solid-phase speciation was measured for different stages of leaching using X-ray absorption near edge structure (XANES) spectroscopy at the P K-edge. When soil columns were leached with up to 56 column pore volumes of 1 mM citrate solutions, no P was detected in column effluent samples, whereas aluminum (Al) and iron (Fe) increased up to 30 and 1.4 µmol L−1, respectively. The XANES analysis suggested that with increased leaching, a minor proportion of phosphate adsorbed on Fe-oxides increased as phosphate adsorbed on Al-oxides decreased. The results indicated that citrate tends to induce minor species redistribution of phosphate between Al- and Fe-oxide bound forms, but P mobilization was trivial compared with complexometric mobilization of Fe and Al.}, number={17}, journal={Communications in Soil Science and Plant Analysis}, author={Santos, S.R. and Hesterberg, D. and Alleoni, L.R.F.}, year={2017}, pages={1977–1988} }
 @article{deiss_franzluebbers_amoozegar_hesterberg_polizzotto_cubbage_2017, title={Soil Carbon Fractions from an Alluvial Soil Texture Gradient in North Carolina}, volume={81}, ISSN={0361-5995}, url={http://dx.doi.org/10.2136/sssaj2016.09.0304}, DOI={10.2136/sssaj2016.09.0304}, abstractNote={
Core Ideas
Total, mineral‐associated, and mineralizable C fractions varied along a soil texture gradient.
Specific surface area and Fe oxyhydroxides were positively associated with clay concentration.
Soil C fractions were positively associated with surface area and Fe oxides.
Aluminum oxide was not related to clay concentration or specific surface area.
Mineralizable C had the most complex relationship with clay concentration.
Soil texture is known to affect soil organic C (SOC) concentration and microbial activity, but these relationships are not always straightforward. We characterized total, mineral‐associated, and mineralizable C fractions along a gradient of soil texture within a flood plain field in the Coastal Plain region of North Carolina. Soil was collected from 0‐ to 5‐, 5‐ to 15‐, and 15‐ to 30‐cm depth intervals at 204 locations within a 7‐ha area. Samples were analyzed for soil particle size distribution, specific surface area (SSA), oxalate‐extractable Al and Fe to estimate short‐range‐ordered (i.e., poorly crystalline) oxyhydroxides, and soil C fractions. Overall, relationships among soil C fractions, textural classes, and depths were complex. Both SOC (0.4–13.9 g kg–1 soil) and mineral‐associated organic C (0–12 g kg–1 soil) increased as soil clay concentration increased (73–430 g kg–1 soil), but having two distinct slopes in each relationship with an inflection point of ∼150 g clay kg–1 soil at 0 to 5 and 5 to 15 cm and an inflection point of ∼250 g clay kg–1 soil at 15 to 30 cm. As clay concentration increased, SSA (12–76 m2 g–1 soil) and oxalate‐extractable Fe (0.45–5.9 g kg–1 soil) also increased. A weaker relationship was observed between oxalate‐extractable Al (0.38–1.5 g kg–1 soil) and either SSA or mineral‐associated organic C. Mineralizable C increased with increasing clay concentration up until 143 ± 3, 152 ± 5, and 161 ± 11 g kg–1 (0–5, 5–15, and 15–30 cm, respectively), but decreased (0–5 and 5–15 cm) or stayed constant (15–30 cm) at higher clay concentrations. On the basis of untested observations, we surmise that binding of C to oxalate‐extractable Fe contributed to the accumulation of SOC and suppression of mineralizable C as the clay concentration increased. These results suggest that complex soil texture–physicochemical interactions underlie the inherent fertility of floodplain soils.}, number={5}, journal={Soil Science Society of America Journal}, publisher={Wiley}, author={Deiss, Leonardo and Franzluebbers, Alan J. and Amoozegar, Aziz and Hesterberg, Dean and Polizzotto, Matthew and Cubbage, Frederick W.}, year={2017}, month={Sep}, pages={1096–1106} }
 @article{hesterberg_mcnulty_thieme_2017, title={Speciation of Soil Phosphorus Assessed by XANES Spectroscopy at Different Spatial Scales}, volume={46}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85034231515&partnerID=MN8TOARS}, DOI={10.2134/jeq2016.11.0431}, abstractNote={Precise management of soil phosphorus (P) to meet competing demands of agriculture and environmental protection can benefit from more comprehensive characterization of P speciation in soils. Our objectives were to provide spatial context for spectroscopic analyses of soil P speciation in relation to molecular‐scale species and landscape‐scale management of P, and to compare soil P‐species diversity from spectroscopic measurements at submicron and millimeter scales. The spatial range of ∼26 orders of magnitude between atomic and field scales presents a challenge to upscaling and downscaling information from spectroscopic analyses of soils. Scanning fluorescence X‐ray microscopy images of a 50‐μm × 45‐μm area of an organic soil sample showed heterogeneous distributions of P, Al, and Si. Microscale X‐ray absorption near edge structure (μ‐XANES) spectra collected at the P K‐edge from 12 spots on the soil sample exhibited diverse features that indicated variations in highly localized P speciation. Linear combination fitting analysis of the μ‐XANES spectra included various proportions of three standards that appeared in fits for most spots and five standards that appeared in fits for one spot each. The fit to a bulk‐soil spectrum was dominated by two of the common standards in the μ‐XANES fits, and a fit to the sum of μ‐XANES spectra included four of the standards. These results illustrate a gain in P species sensitivity from spatially resolved XANES analysis. Integrating spectroscopic analyses from multiple scales determines soil P species diversity and will ultimately help connect speciation to the chemical reactivity and mobility of P in soils.}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Hesterberg, Dean and McNulty, Ian and Thieme, Juergen}, year={2017}, pages={1190–1197} }
 @article{colzato_kamogawa_carvalho_alleoni_hesterberg_2017, title={Temporal Changes in Cadmium Speciation in Brazilian Soils Evaluated Using Cd L-III-Edge XANES and Chemical Fractionation}, volume={46}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85034243455&partnerID=MN8TOARS}, DOI={10.2134/jeq2016.08.0316}, abstractNote={Chemical speciation of soil cadmium (Cd) dictates its mobility and potential toxicity in the environment. Our objective was to compare temporal changes in speciation of Cd(II) reacted with samples from six Brazilian soils having varying Cd(II) sorption capacities. Cadmium LIII–edge X‐ray absorption near edge structure (XANES) analysis showed there were short‐term changes in speciation after reaction with 4.45 mmol Cd kg−1 for 0.5 and 6 h. Chemical fractionation evaluated changes in Cd extractability after reaction with 89 μmol Cd kg−1 for up to 4 mo. The XANES spectral fits suggested that Cd(II) bound with organic matter was a dominant species in all samples, along with Cd(II) bound with iron and aluminum oxides or montmorillonite. In several samples, CdCl2 apparently precipitated from aqueous Cd(II) during drying. The XANES spectral fits typically showed <25% change in speciation between 0.5 and 6 h of reaction, and chemical fractionation showed significant (p < 0.05) temporal changes in Cd extractability over time in two samples. Our results suggest that Cd(II) discharged into these soils, such as that occurring as a release into the environment, would bind with soil organic matter and oxide minerals or remain dissolved, with little change in speciation in the months following release.}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Colzato, Marina and Kamogawa, Marcos Y. and Carvalho, Hudson W. P. and Alleoni, Luis R. F. and Hesterberg, Dean}, year={2017}, pages={1206–1214} }
 @article{hesterberg_polizzotto_crozier_austin_2016, title={Assessment of trace element impacts on agricultural use of water from the Dan River following the Eden coal ash release}, volume={12}, ISSN={["1551-3793"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84941010545&partnerID=MN8TOARS}, DOI={10.1002/ieam.1669}, abstractNote={ABSTRACT}, number={2}, journal={INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT}, author={Hesterberg, Dean and Polizzotto, Matthew L. and Crozier, Carl and Austin, Robert E.}, year={2016}, month={Apr}, pages={353–363} }
 @article{lopez_hesterberg_funk_buchwalter_2016, title={Bioaccumulation Dynamics of Arsenate at the Base of Aquatic Food Webs}, volume={50}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84975471905&partnerID=MN8TOARS}, DOI={10.1021/acs.est.6b01453}, abstractNote={Periphyton is an important food source at the base of freshwater ecosystems that tends to bioconcentrate trace elements making them trophically available. The potential for arsenic-a trace element of particular concern due to its widespread occurrence, toxicity, and carcinogenicity-to bioconcentrate in periphyton and thus be available to benthic grazers is less well characterized. To better understand arsenate bioaccumulation dynamics in lotic food webs, we used a radiotracer approach to characterize accumulation in periphyton and subsequent trophic transfer to benthic grazers. Periphyton bioconcentrated As between 3,200-9,700-fold (dry weight) over 8 days without reaching steady state, suggesting that periphyton is a major sink for arsenate. However, As-enriched periphyton as a food source for the mayfly Neocloeon triangulifer resulted in negligible As accumulation in a full lifecycle exposure. Additional studies estimate dietary assimilation efficiency in several primary consumers ranging from 22% in the mayfly N. triangulifer to 75% in the mayfly Isonychia sp. X-ray fluorescence mapping revealed that As was predominantly associated with iron oxides in periphyton. We speculate that As adsorption to Fe in periphyton may play a role in reducing dietary bioavailability. Together, these results suggest that trophic movement of As in lotic food webs is relatively low, though species differences in bioaccumulation patterns are important.}, number={12}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Lopez, Adeline R. and Hesterberg, Dean R. and Funk, David H. and Buchwalter, David B.}, year={2016}, month={Jun}, pages={6556–6564} }
 @article{lopez_hesterberg_funk_buchwalter_2016, title={Coal ash constituents at the base of aquatic food webs: Processes affecting bioaccumulation and trophic transfer}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85015255475&partnerID=MN8TOARS}, number={465}, journal={Water Resources Research Institute News of the University of North Carolina}, author={Lopez, A.R. and Hesterberg, D.R. and Funk, D.H. and Buchwalter, D.B.}, year={2016} }
 @article{oh_hesterberg_nelson_niedziela_2016, title={Desorption Characteristics of Three Mineral Oxides and a Non-crystalline Aluminosilicate for Supplying Phosphate in Soilless Root Media}, volume={47}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84964088588&partnerID=MN8TOARS}, DOI={10.1080/00103624.2016.1146753}, abstractNote={ABSTRACT The objective was to evaluate phosphate desorption characteristics of synthetic hematite, goethite, and allophane and commercial alumina after loading at maximum adsorbed phosphate levels to determine their potential to release phosphate at a constant, low level to sustain plant growth in soilless media and reduce phosphate leaching. Desorption isotherms were measured at pH 6.4 ± 0.1 using a continuously stirred-flow reactor. The time period during which dissolved phosphate was maintained within the range of 5–0.2 mg·L−1 phosphate-P decreased in the order: allophane (12.4 d) > alumina (4.6 d) > goethite (3.6 d) > hematite (1.9 d). Allophane released the most phosphate during the desorption process (40% of maximum adsorbed phosphate; 12.7 mg∙g−1) followed by alumina and goethite (19–20%; ≈2.5 mg∙g−1) and lastly hematite (5%; 0.1 mg∙g−1). Allophane demonstrated the greatest potential as a phosphate-charged source for soilless root media, in amount and duration of phosphate release.}, number={6}, journal={Communications in Soil Science and Plant Analysis}, author={Oh, Y.-M. and Hesterberg, D.L. and Nelson, P.V. and Niedziela, C.E.}, year={2016}, pages={753–760} }
 @inproceedings{askar_youssef_chescheir_hesterberg_amoozegar_skaggs_2016, title={Development of a macro-pore flow and transport component for DRAINMOD, a step towards modeling phosphorus fate and transport in drained agricultural land}, volume={2016-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85045761634&partnerID=MN8TOARS}, DOI={10.13031/ids.20162492913}, abstractNote={<abstract> <b><sc>Abstract.</sc></b> Artificially drained cropland has recently been identified as a possible source of elevated phosphourus (P) levels in Lake Erie. There is a growing need for developing new models or enhancing existing models to adequately represent different hydrological and biogeochemical processes affecting P fate and transport in artificially drained fields. Since P is highly immobile in soil, most P modeling studies have focused on surface runoff losses ignoring subsurface movement of P. Subsurface drainage, however, can be a critical pathway for P loss, particularly in the presence of macropore flow. Existing models lack or oversimplify integration of hydrological and biogeochemical processes regulating P dynamics in drained agro-ecosystems. A Phosphorus component to DRAINMOD suite of models, namely DRAINMOD-P, is currently being developed. Key hydrological and biochemical processes affecting P dynamics will be represented in the DRAINMOD-P model using a simple P cycle similar to the EPIC model. DRAINMOD hydrological component will be enhanced by adding routines for simulating macropore flow, a key pathway for subsurface transport of P, using procedures similar to MACRO model. The model will simulate water flow and solute transport in both soluble and particulate forms through macropores. The model will also be enhanced to simulate soil erosion and associated surface particulate P transport. The developed model will be tested using field measurements from artificially drained agricultural fields in North Carolina and Ohio. This abstract provides a detailed description of the modeling approach adopted in DRAINMOD to simulate the flow and transport in soil macro-pores}, booktitle={10th International Drainage Symposium 2016}, author={Askar, M.H. and Youssef, M.A. and Chescheir, G.M. and Hesterberg, D.L. and Amoozegar, A. and Skaggs, R.W.}, year={2016}, pages={151–155} }
 @article{oh_nelson_hesterberg_niedziela_2016, title={Efficacy of a Phosphate-Charged Soil Material in Supplying Phosphate for Plant Growth in Soilless Root Media}, volume={2016}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84965120040&partnerID=MN8TOARS}, DOI={10.1155/2016/8296560}, abstractNote={A soil material high in crystalline Fe hydrous oxides and noncrystalline Al hydrous oxides collected from the Bw horizon of a Hemcross soil containing allophane from the state of Oregon was charged with phosphate-P at rates of 0, 2.2, and 6.5 mg·g−1, added to a soilless root medium at 5% and 10% by volume, and evaluated for its potential to supply phosphate at a low, stable concentration during 14 weeks of tomato (Solanum esculentum L.) seedling growth. Incorporation of the soil material improved pH stability, whether it was charged with phosphate or not. Bulk solution phosphate-P concentrations in the range of 0.13 to 0.34 mg·dm−3 were associated with P deficiency. The only treatment that sustained an adequate bulk solution concentration of phosphate-P above 0.34 mg·dm−3 for the 14 weeks of testing contained 10% soil material charged with 6.5 mg·g−1 P, but initial dissolved P concentrations were too high (>5 mg·g−1 phosphate-P) from the standpoint of phosphate leaching. The treatment amended with 10% soil material charged with 2.2 mg·g−1 P maintained phosphate-P within an acceptable range of 0.4 to 2.3 mg·dm−3 for 48 d in a medium receiving no postplant phosphate fertilization.}, journal={International Journal of Agronomy}, author={Oh, Y.-M. and Nelson, P.V. and Hesterberg, D.L. and Niedziela, C.E.}, year={2016} }
 @article{eriksson_hillier_hesterberg_klysubun_ulen_gustafsson_2016, title={Evolution of phosphorus speciation with depth in an agricultural soil profile}, volume={280}, ISSN={["1872-6259"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84974653012&partnerID=MN8TOARS}, DOI={10.1016/j.geoderma.2016.06.004}, abstractNote={With time, different soil-forming processes such as weathering, plant growth, accumulation of organic matter, and cultivation are likely to affect phosphorus (P) speciation. In this study, the depth distribution of P species was investigated for an agricultural clay soil, Lanna, Sweden. Small amounts of apatite-P was demonstrated in the topsoil whereas the speciation of P at 70–100 cm depth consisted of approximately 86% apatite according to P K-edge XANES (X-ray absorption near-edge structure) spectroscopy. Because there were only minor differences in bulk mineralogy and texture, these variations in P speciation were interpreted as the result of apatite weathering of the topsoil. Speciation modeling on soil extracts supported this idea: hydroxyapatite was not thermodynamically stable in the top 50 cm of the soil. Apatite was enriched in the bulk soil relative to the clay fraction, as expected during apatite dissolution. Combined results from batch experiments, XANES spectroscopy and X-ray diffraction suggested chemical transformations of the topsoil as a result from accumulation of organic matter and airing from tillage followed by enhanced weathering of apatite, amphiboles, clay minerals, and iron oxides. This caused the formation of poorly crystalline secondary iron and aluminum (hydr)oxides in the topsoil, which retained part of the released P from apatite. Other P was incorporated into organic forms. Furthermore, the results also showed that short-term acidification below the current pH value (below 5.5 in the topsoil and 7.2 in the deeper subsoil) caused significant solubilization of P. This is attributed to two different mechanisms: the instability of Al-containing sorbents (e.g. Al hydroxides) at low pH (in the topsoil), and the acid-mediated dissolution of apatite (the subsoil).}, journal={GEODERMA}, author={Eriksson, Ann Kristin and Hillier, Stephen and Hesterberg, Dean and Klysubun, Wantana and Ulen, Barbro and Gustafsson, Jon Petter}, year={2016}, month={Oct}, pages={29–37} }
 @article{rippy_nelson_hesterberg_niedziela_kamprath_bilderback_2016, title={Importance of Limestone Specific Surface for Assessing Neutralization Effectiveness in Soilless Root Substrate}, volume={47}, ISSN={["1532-2416"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84961212516&partnerID=MN8TOARS}, DOI={10.1080/00103624.2016.1141926}, abstractNote={ABSTRACT The relationship of specific surface to particle diameter and calcium carbonate (CaCO3) content of limestone was examined. Limestones obtained from 20 North American quarries were wet sieved into eight particle diameter fractions (600 to ˂38 µm). Specific surface of particles was measured in each fraction following the Brunauer-Emmett-Teller theory. The range in specific surface across the 20 sources varied from 74-fold in the coarsest particles (600–300 µm) to 20-fold in the finest particles (˂38 µm). The pattern of specific surface progressing from the coarsest to the finest particles varied radically between sources. The relationship between specific surface and CaCO3 content was likewise very weak. While particle diameter and CaCO3 equivalent remain the traditional measurements for defining limestone for field production, specific surface provides additional information valuable to define the stricter neutralization capacities of limestone for soilless root substrates.}, number={4}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Rippy, Janet F. M. and Nelson, Paul V. and Hesterberg, Dean L. and Niedziela, Carl E., Jr. and Kamprath, Eugene J. and Bilderback, Ted}, year={2016}, month={Feb}, pages={521–526} }
 @article{santos_hesterberg_mattiello_vergutz_barreto_silva_souza filho_2016, title={Increasing Soluble Phosphate Species by Treatment of Phosphate Rocks with Acidic Waste}, volume={45}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85003876062&partnerID=MN8TOARS}, DOI={10.2134/jeq2016.03.0079}, abstractNote={The development of efficient fertilizers with a diminished environmental footprint will help meet the increasing demand for food and nutrients by a growing global population. Our objective was to evaluate whether an acidic mine waste (AMW) could be used beneficially by reacting it with sparingly soluble phosphate rocks (PRs) to produce more soluble P fertilizer materials. Three PRs from Brazil and Peru were reacted with different concentrations of AMW. Changes in mineralogy and P species were determined using a combination of X‐ray diffraction and phosphorus K‐edge XANES spectroscopy, in addition to extractable P concentrations. Increasing the AMW concentration typically increased extractable P. X‐ray diffraction data showed transformation of apatite to other species when PRs were reacted with AMW at ≥50% (v/v) in water, with gypsum or anhydrite forming at AMW concentrations as low as 12.5%. Linear combination fitting analysis of X‐ray absorption near edge structure spectra also indicated a progressive transformation of apatite to noncrystalline Fe(III)‐phosphate and more soluble Ca‐phosphates with increasing AMW concentration. Because this AMW is costly to dispose of, reacting it with PR to produce a higher‐grade phosphate fertilizer material could decrease the environmental impacts of the AMW and diminish the consumption of pure acids in conventional P fertilizer production.}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Santos, Wedisson O. and Hesterberg, Dean and Mattiello, Edson M. and Vergutz, Leonardus and Barreto, Matheus S. C. and Silva, Ivo R. and Souza Filho, Luiz F. S.}, year={2016}, pages={1988–1997} }
 @article{eriksson_hesterberg_klysubun_gustafsson_2016, title={Phosphorus dynamics in Swedish agricultural soils as influenced by fertilization and mineralogical properties: Insights gained from batch experiments and XANES spectroscopy}, volume={566}, ISSN={["1879-1026"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84989879198&partnerID=MN8TOARS}, DOI={10.1016/j.scitotenv.2016.05.225}, abstractNote={The soil chemistry of phosphorus (P) is important for understanding the processes governing plant availability as well as the risk of environmental losses of P. The objective of this research was to investigate both the speciation and the pH-dependent solubility patterns of P in clayey agricultural soils in relation to soil mineralogy and fertilization history. The study focused on soil samples from six fields that were subjected to different P fertilization regimes for periods of 45 to 57years. Soil P speciation was analyzed by P K-edge XANES spectroscopy and chemical fractionation, sorption isotherms were constructed, and dissolved P was measured as a function of pH. The XANES fitting results showed that organic P and P adsorbed to Fe and Al (hydr)oxides were common P constituents in all soils. Calcium phosphates were identified in five of six soil samples. The XANES results also indicated an increase in P adsorbed to Al and to a lesser extent Fe (hydr)oxides as a result of fertilization. Moreover, the fluorescence intensity from the P K-edge XANES analysis was most strongly correlated with HCl-digestible P (r=0.81***). Consistent with the XANES analysis, laboratory sorption isotherm models showed that the Freundlich sorption coefficient (KF) was most closely related to oxalate-extractable Al. Greater proportions of Ca phosphate in two of the heavily fertilized soils in combination with enhanced PO4 solubilization upon sample acidification indicated neoformation of Ca-phosphate precipitates. The results for the unfertilized soil samples generally showed a minimum in dissolved PO4 between pH6.5 and 7.5, with increases particularly at lower pH. This behavior can be explained either by the dissolution of Al-hydroxide-type sorbents or Ca phosphates at lower pH. In fertilized soils, there was no consistent trend in pH-dependent solubilization of P, with a complex relationship to solid-phase speciation. To conclude, inorganic P species changed most dynamically in agricultural clay soils over a period of several decades, and the role of pH in the solubilization of P depended mainly on P fertilization history and the content of reactive Ca phosphates.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Eriksson, Ann Kristin and Hesterberg, Dean and Klysubun, Wantana and Gustafsson, Jon Petter}, year={2016}, month={Oct}, pages={1410–1419} }
 @article{gillispie_austin_rivera_bolich_duckworth_bradley_amoozegar_hesterberg_polizzotto_2016, title={Soil Weathering as an Engine for Manganese Contamination of Well Water}, volume={50}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84988464669&partnerID=MN8TOARS}, DOI={10.1021/acs.est.6b01686}, abstractNote={Manganese (Mn) contamination of well water is recognized as an environmental health concern. In the southeastern Piedmont region of the United States, well water Mn concentrations can be >2 orders of magnitude above health limits, but the specific sources and causes of elevated Mn in groundwater are generally unknown. Here, using field, laboratory, spectroscopic, and geospatial analyses, we propose that natural pedogenetic and hydrogeochemical processes couple to export Mn from the near-surface to fractured-bedrock aquifers within the Piedmont. Dissolved Mn concentrations are greatest just below the water table and decrease with depth. Solid-phase concentration, chemical extraction, and X-ray absorption spectroscopy data show that secondary Mn oxides accumulate near the water table within the chemically weathering saprolite, whereas less-reactive, primary Mn-bearing minerals dominate Mn speciation within the physically weathered transition zone and bedrock. Mass-balance calculations indicate soil weathering has depleted over 40% of the original solid-phase Mn from the near-surface, and hydrologic gradients provide a driving force for downward delivery of Mn. Overall, we estimate that >1 million people in the southeastern Piedmont consume well water containing Mn at concentrations exceeding recommended standards, and collectively, these results suggest that integrated soil-bedrock-system analyses are needed to predict and manage Mn in drinking-water wells.}, number={18}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Gillispie, Elizabeth C. and Austin, Robert E. and Rivera, Nelson A. and Bolich, Rick and Duckworth, Owen W. and Bradley, Phil and Amoozegar, Aziz and Hesterberg, Dean and Polizzotto, Matthew L.}, year={2016}, month={Sep}, pages={9963–9971} }
 @article{rivera_kaur_hesterberg_ward_austin_duckworth_2015, title={Chemical Composition, Speciation, and Elemental Associations in Coal Fly Ash Samples Related to the Kingston Ash Spill}, volume={29}, ISSN={["1520-5029"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84923296129&partnerID=MN8TOARS}, DOI={10.1021/ef501258m}, abstractNote={Environmental impacts of potentially toxic trace elements from coal fly ash are controlled in part by the mineralogy of the ash matrix and the chemical speciation of the trace elements. Our objective was to characterize the chemical and mineralogical composition of fly ash samples that are pertinent to the 2008 release of coal ash from a containment area at the Tennessee Valley Authority (TVA) Kingston fossil plant, which left 4 to 500 t of trace elements in adjoining river systems. Three fly ash samples were analyzed for elemental composition by digestion or neutron activation analysis, mineralogy and macroelement speciation by conventional and synchrotron-based X-ray diffraction (XRD and SXRD) and X-ray absorption spectroscopy (XAS), and for spatial associations of elements by electron probe microanalysis (EPMA). Ash samples were mainly composed of Si (20–27% w/w), Al (10–14% w/w), Fe (4–6% w/w), and Ca (4–6% w/w). Concentrations of selected trace elements ranged from 8 to 1480 mg kg–1, with the followi...}, number={2}, journal={ENERGY & FUELS}, author={Rivera, Nelson and Kaur, Navdeep and Hesterberg, Dean and Ward, Colin R. and Austin, Robert E. and Duckworth, Owen W.}, year={2015}, month={Feb}, pages={954–967} }
 @article{eriksson_gustafsson_hesterberg_2015, title={Phosphorus speciation of clay fractions from long-term fertility experiments in Sweden}, volume={241}, ISSN={["1872-6259"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84919934924&partnerID=MN8TOARS}, DOI={10.1016/j.geoderma.2014.10.023}, abstractNote={Phosphorus (P) losses from agricultural soils constitute a main driver for eutrophication of the Baltic Sea. There is limited knowledge about sorption and release processes of P in these soils, especially concerning the effects of fertilization. In this study, P speciation of the clay fractions from six different soils in long-term fertility experiments in Sweden was investigated by P K-edge XANES spectroscopy. As expected, unfertilized soils had lower concentrations of acid-digestible P compared with fertilized soils. Based on best-fit standards that emerged from linear combination fitting (LCF) of XANES spectra, phosphate sorbed on iron (Fe) (hydr)oxides was a dominant P species in clay fractions from unfertilized soils containing more than 35 mmol kg− 1 of oxalate-extractable Fe. In contrast, P sorbed on aluminum (Al) (hydr)oxides predominated in soils with lower concentrations of oxalate-extractable Fe. A greater proportion of organically bound P was fit for soil samples containing > 2% organic carbon. The soils included one calcareous soil for which a greater proportion of P was fit as apatite. After long-term fertilization, P had accumulated mainly as P adsorbed to Al (hydr)oxides according to the XANES analysis. Our research shows that P speciation in fertilized agricultural soils depended on the level of P buildup and on the soil properties.}, journal={GEODERMA}, author={Eriksson, Ann Kristin and Gustafsson, Jon Petter and Hesterberg, Dean}, year={2015}, month={Mar}, pages={68–74} }
 @book{barnes_nelson_whipker_hesterberg_shi_2014, title={Fertilizer formulation effect on pH of fallow versus planted container substrate}, volume={1034}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84902270094&partnerID=MN8TOARS}, journal={Acta Horticulturae}, author={Barnes, J. and Nelson, P. and Whipker, B.E. and Hesterberg, D. and Shi, W.}, year={2014}, pages={465–470} }
 @article{guinness_fuentes_hesterberg_polizzotto_2014, title={Multivariate spatial modeling of conditional dependence in microscale soil elemental composition data}, volume={9}, ISSN={2211-6753}, url={http://dx.doi.org/10.1016/J.SPASTA.2014.03.009}, DOI={10.1016/j.spasta.2014.03.009}, abstractNote={The mobility and environmental impacts of toxic trace elements are regulated by their reactions with soils, which are complex heterogeneous mixtures of minerals and organic matter. We describe an experiment that maps the composition of elements on an individual soil sand grain using X-ray fluorescence microprobe analyses, after the grain is treated with arsenic solutions, resulting in multivariate spatial lattice maps of elemental abundance. To understand the behavior of arsenic in soils, it is important to disentangle the complex multivariate relationships among the elements in the sample. The abundance of most elements, including arsenic, correlates strongly with that of iron; but conditional on the amount of iron, some elements mitigate or potentiate the accumulation of arsenic. This problem motivates our work to define conditional correlation in spatial lattice models and give general conditions under which two components are conditionally uncorrelated given the rest. We describe how to enforce that two components are conditionally uncorrelated given a third in parametric models, which provides a basis for likelihood ratio tests for conditional correlation between arsenic and chromium given iron. We show how to apply our results to big datasets using the Whittle likelihood, and we demonstrate through simulation that tapering improves Whittle likelihood parameter estimates governing cross covariance.}, number={C}, journal={Spatial Statistics}, publisher={Elsevier BV}, author={Guinness, Joseph and Fuentes, Montserrat and Hesterberg, Dean and Polizzotto, Matthew}, year={2014}, month={Aug}, pages={93–108} }
 @article{barnes_nelson_whipker_dickey_hesterberg_shi_2014, title={Statistical model for describing macronutrient impacts on container substrate pH over time}, volume={49}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84894102893&partnerID=MN8TOARS}, number={2}, journal={HortScience}, author={Barnes, J. and Nelson, P. and Whipker, B.E. and Dickey, D.A. and Hesterberg, D. and Shi, W.}, year={2014}, pages={207–214} }
 @article{conley_funk_hesterberg_hsu_kan_liu_buchwalter_2013, title={Bioconcentration and Biotransformation of Selenite versus Selenate Exposed Periphyton and Subsequent Toxicity to the Mayfly Centroptilum triangulifer}, volume={47}, ISSN={["0013-936X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84880536702&partnerID=MN8TOARS}, DOI={10.1021/es400643x}, abstractNote={Little is known about the bioaccumulation dynamics, biotransformation processes, or subsequent toxicity to consumers of dissolved selenite (SeO3) versus selenate (SeO4) uptake into aquatic primary producer communities. To address these data gaps, we examined SeO3 and SeO4 bioconcentration into complex freshwater periphyton communities under static and static-renewal conditions. Further, we explored periphyton biotransformation of Se species using X-ray absorption near edge structure (XANES) spectroscopy analysis and changes in the periphyton associated microbial consortium using denaturing gradient gel electrophoresis (DGGE). Last, we fed differentially treated periphyton to the mayfly Centroptilum triangulifer in full life cycle exposures to assess toxicity. Selenite exposed periphyton readily bioconcentrated Se while, in contrast, initial periphyton uptake of SeO4 was negligible, but over time periphyton [Se] increased steadily in conjunction with the formation of dissolved SeO3. XANES analyses revealed that both SeO3 and SeO4 treated periphyton biotransformed Se similarly with speciation dominated by organo-selenide (∼61%). Mayfly survival, secondary production, and time to emergence were similar in both SeO3 and SeO4 treated periphyton exposures with significant adverse effects at 12.8 μg g(-1) ((d.w.) secondary production) and 36 μg g(-1) ((d.w.) survival and development time). Overall, dissolved selenium speciation, residence time, and organisms at the base of aquatic food webs appear to be the principal determinants of Se bioaccumulation and toxicity.}, number={14}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Conley, Justin M. and Funk, David H. and Hesterberg, Dean H. and Hsu, Liang-Ching and Kan, Jinjun and Liu, Yu-Ting and Buchwalter, David B.}, year={2013}, month={Jul}, pages={7965–7973} }
 @article{cook_hesterberg_2013, title={Comparison of Trees and Grasses for Rhizoremediation of Petroleum Hydrocarbons}, volume={15}, ISSN={["1549-7879"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84874598499&partnerID=MN8TOARS}, DOI={10.1080/15226514.2012.760518}, abstractNote={Rhizoremediation of petroleum contaminants is a phytoremediation process that depends on interactions among plants, microbes, and soils. Trees and grasses are commonly used for phytoremediation, with trees typically being chosen for remediation of BTEX while grasses are more commonly used for remediation of PAHs and total petroleum hydrocarbons. The objective of this review was to compare the effectiveness of trees and grasses for rhizoremediation of hydrocarbons and address the advantages of each vegetation type. Grasses were more heavily represented in the literature and therefore demonstrated a wider range of effectiveness. However, the greater biomass and depth of tree roots may have greater potential for promoting environmental conditions that can improve rhizoremediation, such as increased metabolizable organic carbon, oxygen, and water. Overall, we found little difference between grasses and trees with respect to average reduction of hydrocarbons for studies that compared planted treatments with a control. Additional detailed investigations into plant attributes that most influence hydrocarbon degradation rates should provide data needed to determine the potential for rhizoremediation with trees or grasses for a given site and identify which plant characteristics are most important.}, number={9}, journal={INTERNATIONAL JOURNAL OF PHYTOREMEDIATION}, author={Cook, Rachel L. and Hesterberg, Dean}, year={2013}, month={Oct}, pages={844–860} }
 @article{sjostedt_persson_hesterberg_kleja_borg_gustafsson_2013, title={Iron speciation in soft-water lakes and soils as determined by EXAFS spectroscopy and geochemical modelling}, volume={105}, ISSN={["1872-9533"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84872550254&partnerID=MN8TOARS}, DOI={10.1016/j.gca.2012.11.035}, abstractNote={Complexation of iron by organic matter can potentially compete with toxic metals for binding sites. Iron(III) forms both monomeric and di/trimeric complexes with fulvic and humic acids, but the nature and extent of complexation with natural organic matter samples from soft-water lakes has not been extensively studied. The aim of this study was to determine the coordination of iron in complexes with organic matter in two soft-water lakes and in the surrounding Oe soil horizons. Iron K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy was performed on particles and large colloids (>0.45 μm) collected by in-line pre-filtration, and on smaller colloids isolated both on an AGMP-1 anion-exchange column and by concentration using 1000 Da ultrafiltration. The results showed that iron(III) was mainly present in monomeric complexes with organic matter, both in the lake water smaller colloids and in the soil samples. Evidence for iron(III) (hydr)oxides was found for the lake particles, in the ultrafiltration retentates, and in some of the soils. Overall, the results suggest that complexation of iron(III) to organic matter prevents hydrolysis into polymeric forms. Strong complexation of iron(III) would lead to competition with other metals for organic-matter binding sites.}, journal={GEOCHIMICA ET COSMOCHIMICA ACTA}, author={Sjostedt, Carin and Persson, Ingmar and Hesterberg, Dean and Kleja, Dan Berggren and Borg, Hans and Gustafsson, Jon Petter}, year={2013}, month={Mar}, pages={172–186} }
 @article{morris_hesterberg_2012, title={Iron(III) Coordination and Phosphate Sorption in Peat Reacted with Ferric or Ferrous Iron}, volume={76}, ISSN={["1435-0661"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84855461884&partnerID=MN8TOARS}, DOI={10.2136/sssaj2011.0097}, abstractNote={The molecular bonding configuration of Fe(III) associated with organic matter (OM) in soils potentially affects its binding affinity, reducibility, mobility, and interactions with other cations and anions. Given that Fe(III) can be incorporated into soil OM either directly as Fe(III) or through oxidation of Fe(II), the coordination and reactivity of OM‐associated Fe(III) may depend on soil redox conditions. Our objective was to determine if the molecular coordination environment and phosphate sorption characteristics of OM‐associated Fe(III) depend on the pathway of Fe(III) incorporation. Pahokee peat soil material was reacted at pH 2.5 with either Fe(III) or Fe(II) at 300, 900, or 1200 mmol Fe kg−1 peat, equilibrated at pH 6.8 and oxidized. Extended x‐ray absorption fine structure and wavelet transform analyses indicated the presence of mononuclear Fe(III) coordinated with organic ligands in all samples along with polynuclear Fe‐hydroxide species at higher concentrations. The pathway of Fe incorporation did not significantly affect its local coordination environment or phosphate sorption isotherms. Our results suggest that OM‐associated Fe(III) formed under oxidized or reduced soil conditions would have similar molecular‐level coordination and be equally accessible for phosphate sorption.}, number={1}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Morris, Amanda J. and Hesterberg, Dean L.}, year={2012}, month={Jan}, pages={101–109} }
 @article{kim_amatya_broome_hesterberg_choi_2012, title={Sensitivity analysis of the DRAINWAT model applied to an agricultural watershed in the lower coastal plain, North Carolina, USA}, volume={26}, ISSN={["1747-6585"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84857111286&partnerID=MN8TOARS}, DOI={10.1111/j.1747-6593.2011.00283.x}, abstractNote={Abstract}, number={1}, journal={WATER AND ENVIRONMENT JOURNAL}, author={Kim, Hyunwoo and Amatya, Devendra M. and Broome, Stephen W. and Hesterberg, Dean L. and Choi, Minha}, year={2012}, month={Mar}, pages={130–145} }
 @article{churchman_hesterberg_singh_2012, title={Soil clays}, volume={64}, ISSN={["1872-9053"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84865416228&partnerID=MN8TOARS}, DOI={10.1016/j.clay.2012.06.012}, abstractNote={Soil clay minerals significantly influence the accumulation and stabilization of organic carbon (OC). However, the effect of interactions among phyllosilicate clay minerals, native OC and sesquioxides (Fe/Al oxides) on the adsorption-desorption of dissolved organic carbon (DOC) under different background electrolyte types and concentration is poorly understood. A set of batch adsorption-desorption experiments were conducted using pedogenic clays extracted from soils dominated by kaolinite-illite (Kaol-Ill), smectite (Smec) and allophane (Allo). The clay samples were sequentially treated to remove native OC and sesquioxides, and tested for adsorption-desorption of DOC under various solution conditions. All the experiments were conducted at pH 7 using water extractable fraction of OC from wheat residues. DOC adsorption increased with increasing background electrolyte concentration, and the presence of Ca2+ significantly enhanced the uptake in comparison to Na+ due to a possible cationic bridging effect. Under all electrolyte conditions, the maximum DOC adsorption capacity (Qmax) (mg g−1) of the soil clay fractions (SCF) maintained the order: Allo > Smec > Kaol-Ill. A similar order was also observed when the adsorption capacities were normalized to the specific surface area (SSA) of the SCFs (mg m− 2). DOC adsorption showed a positive relationship with SSA, and sesquioxides and allophanic minerals provided the largest contributions to the SSA in the SCF. Removal of sesquioxides from the SCF resulted in a decrease in SSA and thus DOC adsorption, whereas removal of native OC increased the SSA and subsequent DOC adsorption. Because this study used pedogenic SCFs which represented soils formed in different environments instead of processed clays from geological deposits, it provided realistic information about the interaction of DOC with SCF in relation to their native OC and sesquioxide contents. It also revealed the importance of Ca2+ in enhancing the carbon adsorption capacities of these SCFs.}, journal={APPLIED CLAY SCIENCE}, author={Churchman, Jock and Hesterberg, Dean and Singh, Balwant}, year={2012}, month={Aug}, pages={1–3} }
 @article{liu_hesterberg_2011, title={Phosphate Bonding on Noncrystalline Al/Fe-Hydroxide Coprecipitates}, volume={45}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79960947486&partnerID=MN8TOARS}, DOI={10.1021/es201597j}, abstractNote={Poorly crystalline minerals have high sorption capacities for environmentally important chemical species, but molecular-level mechanisms of sorption on complex mineral assemblages remain largely unknown. We determined the distribution of orthophosphate (PO(4)) bonding between Al and Fe in relation to structural properties of Al/Fe-hydroxide coprecipitates. Phosphate was sorbed at concentrations between 0.042 and 0.162 mol P mol(-1) Al+Fe on coprecipitates containing 0, 20, 50, 75, or 100 mol % of metal as Al. Phosphorus XANES analyses showed preferential bonding of PO(4) for Al on coprecipitates with 20 and 50 mol % Al, and no preference for either metal at 75 mol % Al, consistent with X-ray photoelectron spectroscopy (XPS) analyses of near-surface metal distributions. Structural ordering and the Fe-hydroxide domain size in coprecipitates decreased with increasing Al proportion, as shown by X-ray diffraction (XRD) and Fe EXAFS analyses. Structural interactions in coprecipitates imparted unique PO(4) sorption properties compared with isolated Al- or Fe-hydroxide.}, number={15}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Liu, Yu-Ting and Hesterberg, Dean}, year={2011}, month={Aug}, pages={6283–6289} }
 @article{kang_amoozegar_hesterberg_osmond_2011, title={Phosphorus leaching in a sandy soil as affected by organic and inorganic fertilizer sources}, volume={161}, ISSN={["0016-7061"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79951581004&partnerID=MN8TOARS}, DOI={10.1016/j.geoderma.2010.12.019}, abstractNote={Long-term application of phosphorus (P) to soils as fertilizer or manure can increase the potential for P loss to ground and surface waters. Vertical P transport was investigated in a sandy soil material receiving seven different P fertilizer sources: poultry compost, poultry litter, triple superphosphate [Ca(H2PO4)2·H2O], dairy lagoon liquid, swine lagoon liquid, swine lagoon sludge, and dissolved potassium dihydrogen phosphate (KH2PO4). The P sources were surface-applied to soil columns (6.35-cm diameter, 10-cm long) at two rates equivalent to 75 and 150 kg total P ha−1, and columns were intermittently leached with deionized (DI) water. Column effluents were collected for up to 23 pore volumes and analyzed for dissolved reactive phosphorus (DRP) and dissolved organic carbon (DOC). In addition, a P retardation factor was determined for the soil from a P adsorption isotherm. Transport of P through soil columns receiving liquid P sources was simulated by a one-dimensional equilibrium convective–dispersive equation (CDE) based on water-extractable P (WEP) concentrations. Cumulative amounts of DRP leached were linearly related to the amounts of WEP in P source materials (r2 = 0.87***). The recovery of DRP in the column effluents relative to WEP in the applied materials was 126 ± 15% (mean ± standard error) for organic P sources and 66 ± 2% for inorganic P sources. The use of WEP in the CDE model underpredicted P transport in the columns amended with lagoon liquids compared with dissolved KH2PO4. Results indicated that leaching losses of P from land-applied manures exceed the amounts of WEP in source materials because of organic P mineralization and competitive sorption of DOC.}, number={3-4}, journal={GEODERMA}, author={Kang, Jihoon and Amoozegar, Aziz and Hesterberg, Dean and Osmond, Deanna L.}, year={2011}, month={Mar}, pages={194–201} }
 @article{kizewski_liu_morris_hesterberg_2011, title={Spectroscopic Approaches for Phosphorus Speciation in Soils and Other Environmental Systems}, volume={40}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79956124868&partnerID=MN8TOARS}, DOI={10.2134/jeq2010.0169}, abstractNote={In the past decades, environmental scientists have become increasingly involved in developing novel approaches for applying emerging spectroscopic techniques to complex environmental matrices. The objective of this review is to convey the most common chemical species of phosphorus reported for soils, sediments, model systems, and waste materials based on analyses by four spectroscopic techniques: X-ray absorption near-edge structure, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and Raman spectroscopy. Unique information is provided by each technique at a level of specificity that depends in part on matrix complexity. The X-ray absorption near-edge structure and nuclear magnetic resonance techniques reveal inorganic and organic P species in intact environmental matrices or in chemical extracts, whereas the Fourier transform infrared and Raman techniques can provide more specific bonding information about mineral or adsorbed P species in model analogs of matrix components. The most common P species in soils and sediments as indicated by spectroscopy are hydroxyapatite and octacalcium phosphate minerals, phosphate adsorbed on Fe- and Al-oxides, pyrophosphates and polyphosphates, phosphate mono- and di-esters, and phosphonates. Continued advancements in spectroscopic methods should improve speciation-based models of P mobilization and transformations in the environment.}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Kizewski, Fiona and Liu, Yu-Ting and Morris, Amanda and Hesterberg, Dean}, year={2011}, month={May}, pages={751–766} }
 @article{hesterberg_duff_dixon_vepraskas_2011, title={X-ray Microspectroscopy and Chemical Reactions in Soil Microsites}, volume={40}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79956072636&partnerID=MN8TOARS}, DOI={10.2134/jeq2010.0140}, abstractNote={Soils provide long-term storage of environmental contaminants, which helps to protect water and air quality and diminishes negative impacts of contaminants on human and ecosystem health. Characterizing solid-phase chemical species in highly complex matrices is essential for developing principles that can be broadly applied to the wide range of notoriously heterogeneous soils occurring at the earth's surface. In the context of historical developments in soil analytical techniques, we describe applications of bulk-sample and spatially resolved synchrotron X-ray absorption spectroscopy (XAS) for characterizing chemical species of contaminants in soils, and for determining the uniqueness of trace-element reactivity in different soil microsites. Spatially resolved X-ray techniques provide opportunities for following chemical changes within soil microsites that serve as highly localized chemical micro- (or nano-)reactors of unique composition. An example of this microreactor concept is shown for micro-X-ray absorption near edge structure analysis of metal sulfide oxidation in a contaminated soil. One research challenge is to use information and principles developed from microscale soil chemistry for predicting macroscale and field-scale behavior of soil contaminants.}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Hesterberg, Dean and Duff, Martine C. and Dixon, Joe B. and Vepraskas, Michael J.}, year={2011}, month={May}, pages={667–678} }
 @article{hashimoto_smyth_israel_hesterberg_2010, title={LACK OF SOYBEAN ROOT ELONGATION RESPONSES TO MICROMOLAR MAGNESIUM ADDITIONS AND FATE OF ROOT-EXUDED CITRATE IN ACID SUBSOILS}, volume={33}, ISSN={["1532-4087"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-73149088156&partnerID=MN8TOARS}, DOI={10.1080/01904160903434279}, abstractNote={Additions of micromolar concentrations of magnesium (Mg) to hydroponics enhance aluminum (Al) tolerance of soybean by increasing citrate secretion from roots and external complexation of toxic Al species. The objective of this study was to assess the ameliorative effect of Mg additions on soybean root elongation into mineralogically different acid soils. Roots of soybean seedlings grew for 28 days into acid soils treated with three Mg levels in their soil solution (Control, 150 and 300 μM) and lime. Root growth in the acid soils and aboveground dry matter responses to the Mg treatments were less than for the lime treatments. Citrate fate in the acid soils revealed that 66–99% of added citrate was either adsorbed or biodegraded, suggesting that root secreting citrate in the soil abundant with Al and iron (Fe) hydroxides potentially reduces the availability to complex rhizotoxic Al. A calcium (Ca) deficiency may have constrained root growth response to the Mg-treated soils.}, number={2}, journal={JOURNAL OF PLANT NUTRITION}, author={Hashimoto, Yohey and Smyth, T. Jot and Israel, Daniel W. and Hesterberg, Dean}, year={2010}, pages={219–239} }
 @book{hesterberg_2010, title={Macroscale chemical properties and X-ray absorption spectroscopy of soil phosphorus}, volume={34}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77955798731&partnerID=MN8TOARS}, journal={Developments in Soil Science}, author={Hesterberg, D.}, year={2010}, pages={313–356} }
 @article{kizewski_boyle_hesterberg_martin_2010, title={Mixed Anion (Phosphate/Oxalate) Bonding to Iron(III) Materials}, volume={132}, ISSN={["1520-5126"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77749237327&partnerID=MN8TOARS}, DOI={10.1021/ja908807b}, abstractNote={A novel phosphate/oxalate inorganic-organic hybrid material has been prepared to elucidate synthesis and bonding characteristics of iron(III) with both phosphate and organic matter (OM). Such mixed anion bonding of inorganic oxyanions and OM to iron(III) and aluminum(III) in environmental systems has been proposed but not proven, mainly because of the complexity of natural geochemical matrices. The compound reported here with the molecular formula of [C(3)H(12)N(2)](2)[Fe(5)(C(2)O(4))(2)(H(x)PO(4))(8)] (I) was hydrothermally synthesized and characterized by single crystal X-ray diffraction and X-ray absorption spectroscopy (XAS). In this new structure, Fe-O octahedra and P-O tetrahedra are connected by corner-sharing to form a 2-D network in the a-b plane. Oxalate anions cross-link these Fe-P layers constructing a 3-D anionic framework. A diprotonated structure-directing template, DAP (1,3-diaminopropane), resides in the oxalate layer of the structure and offsets the negative charge of the anionic framework. Iron K-edge XANES spectra confirmed that the iron in I is Fe(III). The crystal structure of I is used to successfully fit its Fe K-edge EXAFS spectrum, which exhibits spectral signatures that unambiguously identify iron-phosphate and iron-OM bonding. Such molecular spectroscopic features will be invaluable for the evaluation of complex environmental systems. Furthermore, syntheses demonstrated the critical role of the templating amine to mediate whether or not the iron(III) is reduced by the organic acid.}, number={7}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Kizewski, Fiona R. and Boyle, Paul and Hesterberg, Dean and Martin, James D.}, year={2010}, month={Feb}, pages={2301–2308} }
 @article{bi_hesterberg_duckworth_2010, title={Siderophore-promoted dissolution of cobalt from hydroxide minerals}, volume={74}, ISSN={["1872-9533"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77951296385&partnerID=MN8TOARS}, DOI={10.1016/j.gca.2010.02.028}, abstractNote={Recent research has revealed that siderophores, a class of biogenic ligands with high affinities for Fe(III), can also strongly complex Co(III), an element essential to the normal metabolic function of microbes and animals. This study was conducted to quantify the rates and identify the products and mechanisms of the siderophore-promoted dissolution of Co from synthetic Co-bearing minerals. The dissolution reactions of heterogenite (CoOOH) and four Co-substituted goethites (Co-FeOOH) containing different Co concentrations were investigated in the presence of a trihydroxamate siderophore, desferrioxamine B (DFOB), using batch and flow-through experiments. Results showed that DFOB-promoted dissolution of Co from Co-bearing minerals may occur via pH-dependent ligand-promoted or reductive dissolution mechanisms. For heterogenite, ligand-promoted dissolution was the dominant pathway at neutral to alkaline pH, while production of dissolved Co(II) for pH <6. It was not possible from our data to decouple the separate contributions of homogenous and heterogeneous reduction reactions to the aqueous Co(II) pool. Cobalt substitution in Co-substituted goethite, possibly caused by distortion of goethite structure and increased lattice strain, resulted in enhanced total dissolution rates of both Co and Fe. The DFOB-promoted dissolution rates of Co-bearing minerals, coupled with the high affinity of Co(III) for DFOB, suggest that siderophores may be effective for increasing Co solubility, and thus possibly Co bioavailability. The results also suggest that siderophores may contribute to the mobilization of radioactive 60Co from Co-bearing mineral phases through mineral weathering and dissolution processes.}, number={10}, journal={GEOCHIMICA ET COSMOCHIMICA ACTA}, author={Bi, Yuqiang and Hesterberg, Dean L. and Duckworth, Owen W.}, year={2010}, month={May}, pages={2915–2925} }
 @article{shah_hutchison_hesterberg_grabow_huffman_hardy_parsons_2009, title={Leaching of Nutrients and Trace Elements from Stockpiled Turkey Litter into Soil}, volume={38}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-66649083862&partnerID=MN8TOARS}, DOI={10.2134/jeq2007.0639}, abstractNote={In addition to nutrients, poultry are fed trace elements (e.g., As) for therapeutic purposes. Although a large proportion of the nutrients are assimilated by the birds, nearly all of the As is excreted. Hence, turkey litter constituents can leach into the soil and contaminate shallow ground water when it is stockpiled uncovered on bare soil. This study quantified the leaching of turkey litter constituents from uncovered stockpiles into the underlying soil. Four stockpiles were placed on Orangeburg loamy sand in summer 2004 for 162 d; 14 d after their removal, four stockpiles were created over the same footprints and left over winter for 162 d. Soil samples at depths of 7.6 to 30.5 cm and 30.5 to 61 cm adjacent to and beneath the stockpiles were compared for pH, electrical conductivity, total C, dissolved organic C, N species, P, water‐extractable (WE)‐P, As, WE‐As, Cu, Mn, and Zn. All WE constituents affected the 7.6‐ to 30.5‐cm layer, and some leached deeper; for example, NH4+–N concentrations were 184 and 62 times higher in the shallow and deep layers, respectively. During winter stockpiling, WE‐As concentrations beneath the stockpiles tripled and doubled in the 7.6‐ to 30.5‐cm and 30.5‐ to 61‐cm layers, respectively, with WE‐As being primarily as As(V). Heavy dissolved organic C and WE‐P leaching likely increased solubilization of soil As, although WE‐As concentrations were low due to the Al‐rich soil and low‐As litter. When used as drinking water, shallow ground water should be monitored on farms with a history of litter stockpiling on bare soil; high litter As; and high soil As, Fe, and Mn concentrations.}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Shah, Sanjay B. and Hutchison, Kimberly J. and Hesterberg, Dean L. and Grabow, Garry L. and Huffman, Rodney L. and Hardy, David H. and Parsons, James T.}, year={2009}, pages={1053–1065} }
 @article{kang_hesterberg_osmond_2009, title={Soil Organic Matter Effects on Phosphorus Sorption: A Path Analysis}, volume={73}, ISSN={["1435-0661"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-62549111344&partnerID=MN8TOARS}, DOI={10.2136/sssaj2008.0113}, abstractNote={While P sorption in mineral soils has been extensively studied, P sorption behavior in organic‐rich soils is less known. This study was conducted to determine the relationships between Langmuir P sorption maxima (Smax) and selected physicochemical properties of soils, with particular emphasis on organic matter (OM) content. The Smax values were determined for 72 soil samples from the North Carolina Coastal Plain, along with pH, clay and OM contents, oxalate‐extractable P (Pox), Al (Alox), and Fe (Feox), and Mehlich 3 extractable P (PM3), Al (AlM3), and Fe (FeM3). Path analysis was used to examine direct and indirect effects of soil properties on Smax In the oxalate path analysis, the direct effects of clay, Alox, and Feox on Smax were significant in the order Alox > clay > Feox (P < 0.05). The Smax was highly influenced by the indirect effect of Alox and Feox through OM content. A two‐piece segmented linear relationship existed between Smax and OM and the regression slope in soils with OM ≤ 49 g kg−1 was 10‐fold greater than that for soils with OM > 49 g kg−1 This finding suggested that noncrystalline or organically bound Al and Fe in the soils with OM > 49 g kg−1 is less effective for P sorption than in the soils with lower OM content. In the Mehlich 3 path analysis, the direct effects of clay, OM, and AlM3 on Smax were significant in the order AlM3 > OM > clay (P < 0.05) while the direct effect of FeM3 on Smax was not significant. Oxalate may be better suited than Mehlich 3 as an extractant for predicting P sorption capacity in the Coastal Plain soils.}, number={2}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Kang, Jihoon and Hesterberg, Dean and Osmond, Deanna L.}, year={2009}, pages={360–366} }
 @article{eveborn_gustafsson_hesterberg_hillier_2009, title={XANES Speciation of P in Environmental Samples: An Assessment of Filter Media for on-Site Wastewater Treatment}, volume={43}, ISSN={["0013-936X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-69549090592&partnerID=MN8TOARS}, DOI={10.1021/es901084z}, abstractNote={X-ray absorption near edge structure (XANES) spectroscopy is a useful technique for characterization of chemical species of phosphorus in complex environmental samples. To develop and evaluate bed filters as sustainable on-site wastewater treatment solutions, our objective in this study was to determine the chemical forms of accumulated phosphorus in a selection of promising filter materials: Filtralite P, Filtra P, Polonite, Absol, blast furnace slag, and wollastonite. Full-scale operational wastewater-treatment systems were sampled and in addition, filter samples collected from laboratory studies provided access to additional media and complementary samples. Phosphorus species were characterized using phosphorus K-edge XANES spectroscopy, complemented by X-ray powder diffraction (XRPD) and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). No systematic differences could be seen in the results between laboratory- and full-scale samples. All six filter media contained significant amounts of crystalline calcium phosphates. Some samples also contained amorphous calcium phosphate (>60% of total P in Absol). In Filtralite P and blast furnace slag, more than 35% of the accumulated phosphorus was associated with Fe or Al. Both the power and shortcomings of XANES analysis for characterizing P species in these filter media are discussed.}, number={17}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Eveborn, David and Gustafsson, Jon Petter and Hesterberg, Dean and Hillier, Stephen}, year={2009}, month={Sep}, pages={6515–6521} }
 @book{rippy_nelson_bilderback_swallow_hesterberg_kamprath_jahn_2008, title={Evaluation of limestone physical and chemical properties on neutralization capacity}, volume={779}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-61449091576&partnerID=MN8TOARS}, journal={Acta Horticulturae}, author={Rippy, J.F.M. and Nelson, P.V. and Bilderback, T.E. and Swallow, W.H. and Hesterberg, D.L. and Kamprath, E.J. and Jahn, D.}, year={2008}, pages={139–147} }
 @article{mckinney_hesterberg_2007, title={Kinetics of AgI precipitation from AgCl as affected by background electrolyte}, volume={273}, ISSN={["0236-5731"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34447130388&partnerID=MN8TOARS}, DOI={10.1007/s10967-007-6849-0}, number={2}, journal={JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY}, author={McKinney, D. S. and Hesterberg, D. L.}, year={2007}, month={Aug}, pages={289–297} }
 @article{khare_martin_hesterberg_2007, title={Phosphate bonding configuration on ferrihydrite based on molecular orbital calculations and XANES fingerprinting}, volume={71}, ISSN={["0016-7037"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34548540954&partnerID=MN8TOARS}, DOI={10.1016/j.gca.2007.07.008}, abstractNote={Sorption of phosphate by Fe(III)- and Al(III)-(hydr)oxide minerals regulates the mobility of this potential water pollutant in the environment. The objective of this research was to determine the molecular configuration of phosphate bound on ferrihydrite at pH 6 by interpreting P K-edge XANES spectra in terms of bonding mode. XANES and UV–visible absorption spectra for aqueous Fe(III)–PO4 solutions (Fe/P molar ratio = 0–2.0) provided experimental trends for energies of P(3p)–O(2p) and Fe(3d)–O(2p) antibonding molecular orbitals. Molecular orbitals for Fe(III)–PO4 or Al(III)–PO4 complexes in idealized monodentate or bidentate bonding mode were generated by conceptual bonding arguments, and Extended-Hückel molecular orbital computations were used to understand and assign XANES spectral features to bound electronic states. The strong white line at the absorption edge in P K-edge XANES spectra for Fe–PO4 or Al–PO4 systems is attributable to an electronic transition from a P 1s atomic orbital into P(3p)–O(2p) or P(3p)–O(2p)–Al(3p) antibonding molecular orbitals, respectively. For Fe–PO4 systems, a XANES peak at 2–5 eV below the edge was assigned to a P 1s electron transition into Fe(4p)–O(2p) antibonding molecular orbitals. Similarly, a shoulder on the low-energy side of the white line for variscite corresponds to a transition into Al(3p)–O(2p) orbitals. In monodentate-bonded phosphate, Fe–O bonding is optimized and P–O bonding is weakened, and the converse is true of bidentate-bonded phosphate. These differences explained an inverse correlation between energies of P(3p)–O(2p) and Fe(3d)–O(2p) antibonding molecular orbitals consistent with a monodentate-to-bidentate transition in aqueous Fe(III)–PO4 solutions. The intensity of the XANES pre-edge feature in Fe(III)-bonded systems increased with increasing number of Fe(III)–O–P bonds. Based on the similarity of intensity and splitting of the pre-edge feature for phosphate sorbed on ferrihydrite at 750 mmol/kg at pH 6 and aqueous Fe–PO4 solutions containing predominantly bidentate complexes, XANES results indicated that phosphate adsorbed on ferrihydrite was predominantly a bidentate–binuclear surface complex.}, number={18}, journal={GEOCHIMICA ET COSMOCHIMICA ACTA}, author={Khare, Nidhi and Martin, James D. and Hesterberg, Dean}, year={2007}, month={Sep}, pages={4405–4415} }
 @article{rippy_nelson_hesterberg_kamprath_2007, title={Reaction times of twenty limestones}, volume={38}, ISSN={["1532-2416"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34447308205&partnerID=MN8TOARS}, DOI={10.1080/00103620701435530}, abstractNote={Abstract Particle size and calcium carbonate equivalent characterize agricultural limestone. When agricultural limestone is used for horticultural container substrates, variations in pH among batches of substrate produced with the same limestone rate, as well as pH drift from initial pH, occur. Horticultural endeavors require more detailed characterization of limestone neutralization capacity than is provided for agricultural limestones. Reactivity of twenty limestones encompassing a broad range of calcium and magnesium carbonate were compared. Limestones were wet‐sieved into three particle‐diameter fractions and reacted with ammonium chloride in the presence of steam. Fine particles reacted faster than coarse; however, there was a point beyond which degree of fineness of calcitic limestone no longer affected reactivity. Dolomitic limestones were slower reacting than calcitic. Reactivity within particle fractions of dolomitic and coarse calcitic limestones varied significantly. These results indicate that particle diameter and calcium carbonate equivalent are not the only factors influencing limestone neutralization capacity.}, number={13-14}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Rippy, Janet F. M. and Nelson, Paul V. and Hesterberg, Dean L. and Kamprath, Eugene J.}, year={2007}, pages={1775–1783} }
 @article{hashimoto_smyth_hesterberg_israel_2007, title={Soybean root growth in relation to ionic composition in magnesium-amended acid subsoils: Implications on root citrate ameliorating aluminum constraints}, volume={53}, ISSN={["1747-0765"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-36249018938&partnerID=MN8TOARS}, DOI={10.1111/j.1747-0765.2007.00191.x}, abstractNote={Abstract Hydroponic studies with soybean (Glycine max [L.] Merr.) have shown that µmol L−1 additions of Mg2+ were as effective in ameliorating Al rhizotoxicity as additions of Ca2+in the mmol L−1 concentration range. The objectives of this study were to assess the ameliorative effects of Mg on soybean root growth in acidic subsoils and to relate the soil solution ionic compositions to soybean root growth. Roots of soybean cultivar Plant Introduction 416937 extending from a limed surface soil compartment grew for 28 days into a subsurface compartment containing acid subsoils from the Cecil (oxidic and kaolinitic), Creedmoor (montmorillonitic) and Norfolk (kaolinitic) series. The three Mg treatments consisted of native equilibrium soil solution concentrations in each soil (50 or 100 µmol L−1) and MgCl2 additions to achieve 150 and 300 µmol L−1 Mg (Mg150 and Mg300, respectively) in the soil solutions. Root elongations into Mg-treated subsoils were compared with a CaCO3 treatment limed to achieve a soil pH value of 6. Subsoil root growth responses to the Mg treatments were less than for the lime treatments. Root length relative to the limed treatments for all subsoils (RRL) was poorly related to the activity of the soil solution Al species (Al3+ and Al-hydroxyl species) and Mg2+. However, the RRL values were more closely related to the parameters associated with soil solution Ca activity, including (Ca2+), (Al3+)/(Ca2+) and (Al3+)/([Ca2+] + [Mg2+]), suggesting that Ca could be a primary factor ameliorating Al and H+ rhizotoxicity in these subsoils. Increased tolerance to Al rhizotoxicity of soybean by micromolar Mg additions to hydroponic solutions, inducing citrate secretion from roots to externally complex toxic Al, may be less important in acid subsoils with low native Ca levels.}, number={6}, journal={SOIL SCIENCE AND PLANT NUTRITION}, author={Hashimoto, Yohey and Smyth, T. Jot and Hesterberg, Dean and Israel, Daniel W.}, year={2007}, month={Dec}, pages={753–763} }
 @misc{shober_hesterberg_sims_gardner_2006, title={Characterization of phosphorus species in biosolids and manures using XANES spectroscopy}, volume={35}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33845343243&partnerID=MN8TOARS}, DOI={10.2134/jeq2006.0100}, abstractNote={ABSTRACT}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Shober, Amy L. and Hesterberg, Dean L. and Sims, J. Thomas and Gardner, Sheila}, year={2006}, pages={1983–1993} }
 @article{hesterbery_vos_raats_2006, title={Chemistry of subsurface drain discharge from an agricultural polder soil}, volume={86}, ISSN={["1873-2283"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33750618128&partnerID=MN8TOARS}, DOI={10.1016/j.agwat.2006.07.003}, abstractNote={Protecting groundwater and surface water quality in drained agricultural lands is aided by an understanding of soil physical and chemical processes affecting leaching of plant nutrients and other chemical constituents, and discharge from subsurface drains. Our objectives were to determine which chemical processes most affected discharge of redox-active components and macroelements (mainly base cations) from a subsurface drain, and to assess soil characterization needs for more accurate reactive-transport modeling. We measured the chemical composition of discharge water samples collected for 150 days from a 0.075-ha agricultural field plot on a calcareous polder soil. In light of previously reported two-dimensional, hydrological modeling of subsurface NO3 and Cl discharge, variations in the dissolved concentrations of Mn, Fe, Ca, Mg, Na, K, HCO3, and S could be qualitatively understood in terms of hydrology along with oxidation–reduction (redox), precipitation/dissolution, and cation exchange processes. Elevated concentrations of Mn and Fe in the presence of NO3 during periods of peak flow were consistent with mixing of porewaters from reduced and oxidized soil zones. Discharge samples were supersaturated with respect to pure calcite, and responded only weakly to changes in pH over the measured range of pH 7.2–8.2. Dissolved concentrations of Na, Mg, K, and S depended on their relative affinities for the soil exchanger phase and initial NH4Cl-extractable concentrations throughout the soil profile. Quantitative prediction of reactive components in drain discharge would require coupling of two-dimensional hydrological modeling with modeling of depth-dependent precipitation/dissolution and cation exchange processes, and redox kinetics.}, number={1-2}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Hesterbery, Dean and Vos, Bram and Raats, P. A. C.}, year={2006}, month={Nov}, pages={220–228} }
 @article{fichtner_hesterberg_smyth_shew_2006, title={Differential sensitivity of Phytophthora parasitica var. nicotianae and Thielaviopsis basicola to monomeric aluminum species}, volume={96}, ISBN={0031-949X}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33644892775&partnerID=MN8TOARS}, DOI={10.1094/phyto-96-0212}, abstractNote={ Aluminum (Al) is toxic to many plant pathogens, including Thielaviopsis basicola and Phytophthora parasitica var. nicotianae. Because fungi-toxicity of Al has been described in soils over a wide pH range, multiple species of Al may be responsible for pathogen suppression. The goals of this work were to determine the sensitivity of T. basicola and P. para-sitica var. nicotianae to Al over a range of pH values, quantify the toxicity of monomeric Al species to production of sporangia of P. parasitica var. nicotianae and chlamydospores of T. basicola, and detect the accumulation of Al in pathogen structures. A complete factorial treatment design was used with Al levels ranging from 0 to 100 μM and pH levels ranging from 4 to 6 in a minimal salts medium. The chemistry of test solutions was modeled using GEOCHEM-PC. Colonies were grown in 5% carrot broth, and after 1 or 2 days, the nutrient solution was removed, colonies were rinsed with water, and Al test solutions were added to each of four replicate plates. After 2 days, propagules were counted and colonies were stained with the Al-specific, fluorescent stain lumogallion. The oomycete P. parasitica var. nicotianae was sensitive to multiple monomeric Al species, whereas sensitivity of T. basicola to Al was pH-dependent, suggesting that only Al3+ is responsible for suppression of this fungal pathogen. Chlamydospore production by T. basicola was inhibited at pH values <5.0 and Al levels >20 μM, whereas sporangia production by P. parasitica was inhibited at Al levels as low as 2 μM across all pH values tested. The lumogallion stain was an effective technique for detection of Al in fungal tissues. Aluminum accumulated in sporangia and zoospores of P. parasitica var. nicotianae and in nonmelanized chlamy-dospores of T. basicola, but not in cell walls of either organism. The differential sensitivity of the two organisms may indicate that true fungi respond differently to Al than members of the oomycota, which are more closely related to plants. }, number={3}, journal={Phytopathology}, author={Fichtner, E. J. and Hesterberg, Dean and Smyth, T. J. and Shew, H. D.}, year={2006}, pages={212} }
 @article{murray_hesterberg_2006, title={Iron and phosphate dissolution during abiotic reduction of ferrihydrite-boehmite mixtures}, volume={70}, ISSN={["1435-0661"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33745942293&partnerID=MN8TOARS}, DOI={10.2136/sssaj2005.0292}, abstractNote={Excessive phosphorus loss from soils poses a threat to surface‐water quality. Soils comprise assemblages of multiple minerals, with Fe‐ and Al‐oxides being important for phosphate sorption. Our objective was to measure reductive dissolution of an Fe‐oxide and sorbed orthophosphate as affected by the presence of an Al‐(hydr)oxide mineral. Aqueous suspensions containing 0.5 g ferrihydrite kg−1 and up to 0.7 g boehmite kg−1 and KH2PO4 added at 750 mmol kg−1 of ferrihydrite were abiotically reduced at pH 6.0 for 72 h using 0.5% H2(g) in the presence of a Pt catalyst. A sharp decrease in zero‐order Fe(II) dissolution rate coefficients was observed between 0 and 0.008 g kg−1 of added boehmite, whereas net Fe(II) dissolution was essentially null for boehmite additions ≥ 0.02 g kg−1 Although net dissolution of PO4 occurred over time in the absence of boehmite, a net uptake occurred in the presence of boehmite. Auxiliary experiments suggested that Al(III) dissolved from boehmite decreased Fe(II) dissolution during reduction by sorbing to the ferrihydrite surface and blocking electron transfer. Because PO4 was taken up in excess of the maximum boehmite sorption capacity in systems with ≤ 0.008 g boehmite kg−1, results suggested the formation of Al‐phosphate or an Al(III)–PO4 complex on ferrihydrite surfaces. Phosphorus K‐XANES spectroscopy of samples collected during reduction of a 1:1 ferrihydrite/boehmite mixture showed no consistent change in sorbed PO4 associated with Fe(III) versus Al(III).}, number={4}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Murray, G. Christopher and Hesterberg, Dean}, year={2006}, pages={1318–1327} }
 @article{maguire_hesterberg_gernat_anderson_wineland_grimes_2006, title={Liming poultry manures to decrease soluble phosphorus and suppress the bacteria population}, volume={35}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33646558633&partnerID=MN8TOARS}, DOI={10.2134/jeq2005.0339}, abstractNote={ABSTRACT}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Maguire, R. O. and Hesterberg, D. and Gernat, A. and Anderson, K. and Wineland, M. and Grimes, J.}, year={2006}, pages={849–857} }
 @article{mgrdichian_hesterberg_fitts_yang_sweet_smith_abbamonte_johnson_lewis_kao_2005, title={Meeting Reports: A Passion for Synchrotron Science and its Future}, volume={18}, ISSN={0894-0886 1931-7344}, url={http://dx.doi.org/10.1080/08940880500457008}, DOI={10.1080/08940880500457008}, abstractNote={The speakers at the main session of the 2005 National Synchrotron Light Source (NSLS) Annual Users' Meeting, held on Tuesday, May 24, at Brookhaven National Laboratory (BNL), spoke on many different topics. But they all conveyed excitement for the science performed at the NSLS, and expressed enthusiasm for its proposed successor, the world-leading NSLS-II. The incoming NSLS Users' Executive Committee Chair, Peter Stephens, welcomed the audience to the main meeting, setting a positive and enthusiastic tone for the day's events. He then opened the stage to BNL Director Praveen Chaudhari. Chaudhari commended many attendees for their work to advance NSLS-II.}, number={5}, journal={Synchrotron Radiation News}, publisher={Informa UK Limited}, author={Mgrdichian, Laura and Hesterberg, Dean and Fitts, Jeffrey P. and Yang, Lin and Sweet, Robert and Smith, Ward W. and Abbamonte, Peter and Johnson, Peter and Lewis, Laura H. and Kao, Chi-Chang}, year={2005}, month={Sep}, pages={2–13} }
 @article{khare_hesterberg_martin_2005, title={XANES investigation of phosphate sorption in single and binary systems of iron and aluminum oxide minerals}, volume={39}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-16844386656&partnerID=MN8TOARS}, DOI={10.1021/es049237b}, abstractNote={Phosphate sorption on Fe- and Al-oxide minerals helps regulate the solubility and mobility of P in the environment. The objective of this study was to characterize phosphate adsorption and precipitation in single and binary systems of Fe- and Al-oxide minerals. Varying concentrations of phosphate were reacted for 42 h in aqueous suspensions containing goethite, ferrihydrite, boehmite, or noncrystalline (non-xl) Al-hydroxide, and in 1:1 (by mass) mixed-mineral suspensions of goethite/boehmite and ferrihydrite/ non-xl Al-hydroxide at pH 6 and 22 degrees C. X-ray absorption near edge structure (XANES) spectroscopy was used to detect precipitated phosphate and distinguish PO4 associated with Fe(III) versus Al(III) in mixed-mineral systems. Changes in the full width at half-maximum height (fwhm) in the white-line peak in P K-XANES spectra provided evidence for precipitation in Al-oxide single-mineral systems, but not in goethite or ferrihydrite systems. Similarly, adsorption isotherms and XANES data showed evidence for precipitation in goethite/boehmite mixtures, suggesting that mineral interactive effects on PO4 sorption were minimal. However, sorption in ferrihydrite/non-xl Al-hydroxide systems and a lack of XANES evidence for precipitation indicated that mineral interactions inhibited precipitation in these binary mixtures.}, number={7}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Khare, N and Hesterberg, D and Martin, JD}, year={2005}, month={Apr}, pages={2152–2160} }
 @article{pfeifer_gueye-girardet_reymond_schlegel_temgoua_hesterberg_chou_2004, title={Dispersion of natural arsenic in the Malcantone watershed, Southern Switzerland: field evidence for repeated sorption-desorption and oxidation-reduction processes}, volume={122}, ISSN={["1872-6259"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-4444339983&partnerID=MN8TOARS}, DOI={10.1016/j.geoderma.2004.01.009}, abstractNote={In recent years, elevated arsenic concentrations have been found in waters and soils of many countries, often resulting in a health threat for the local population. Switzerland is not an exception and this paper deals with the release and subsequent fate of arsenic in a 200-km2 mountainous watershed, characterized by crystalline silicate rocks (gneisses, schists, amphibolites) that contain abundant As-bearing sulfide ore deposits, some of which have been mined for iron and gold in the past. Using analytical methods common for mineralogical, ground water and soil studies (XRD, XRF, XAS-XANES and -EXAFS, electron microprobe, extraction, ICP, AAS with hydride generator, ion chromatography), seven different field situations and related dispersion processes of natural arsenic have been studied: (1) release by rock weathering; (2) transport and deposition by water and ice; (3) release of As to the ground and surface water due to increasing pH; (4) accumulation in humic soil horizons; (5) remobilization by reduction in water-saturated soils and stagnant ground waters; (6) remobilization by using P-rich fertilizers or dung and (7) oxidation, precipitation and dilution in surface waters. Comparison of the results with experimental adsorption studies and speciation diagrams from the literature allows us to reconstruct and identify the typical behavior of arsenic in a natural environment under temperate climatic conditions. The main parameters identified are: (a) once liberated from the primary minerals, sorption processes on Fe-oxy-hydroxides dominate over Al-phases, such as Al-hydroxides or clay minerals and limit the As concentrations in the spring and well waters between 20 and 300 μg/l. (b) Precipitation as secondary minerals is limited to the weathering domain, where the As concentrations are still high and not yet too diluted by rain and soils waters. (c) Although neutral and alkaline pH conditions clearly increase the mobility of As, the main factor to mobilize As is a low redox potential (Eh close or below 0 mV), which favors the dissolution of the Fe-oxy-hydroxides on which the As is sorbed. (d) X-ray absorption spectroscopy (XAS) of As in water-logged humic forest soils indicates that the reduction to As III only occurs at the solid–water interface and that the solid contains As as As V. (e) A and Bh horizons of humic cambisols can effectively capture As when As-rich waters flow through them. Complex spatial and temporal variation of the various parameters in a watershed results in repeated mobilization and immobilization of As, which continuously transports As from the upper to the lower part of a watershed and ultimately to the ocean.}, number={2-4}, journal={GEODERMA}, author={Pfeifer, HR and Gueye-Girardet, A and Reymond, D and Schlegel, C and Temgoua, E and Hesterberg, DL and Chou, JWQ}, year={2004}, month={Oct}, pages={205–234} }
 @article{hutchison_hesterberg_2004, title={Dissolution of phosphate in a phosphorus-enriched ultisol as affected by microbial reduction}, volume={33}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-4544353600&partnerID=MN8TOARS}, DOI={10.2134/jeq2004.1793}, abstractNote={ABSTRACT}, number={5}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Hutchison, KJ and Hesterberg, D}, year={2004}, pages={1793–1802} }
 @article{bang_hesterberg_2004, title={Dissolution of trace element contaminants from two coastal plain soils as affected by pH}, volume={33}, ISSN={["1537-2537"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-2442655324&partnerID=MN8TOARS}, DOI={10.2134/jeq2004.0891}, abstractNote={ABSTRACT}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Bang, JS and Hesterberg, D}, year={2004}, pages={891–901} }
 @inproceedings{amoozegar_warren_niewoehner_robarge_hoover_hesterberg_rubin_2004, title={Effect of graywater on soil hydraulic properties}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-27944473100&partnerID=MN8TOARS}, booktitle={Proceedings of the 10th National Symposium on Individual and Small Community Sewage Systems - On-Site Wastewater Treatment X}, author={Amoozegar, A. and Warren, S. and Niewoehner, C. and Robarge, W. and Hoover, M. and Hesterberg, D. and Rubin, R.}, year={2004}, pages={231–240} }
 @article{mckinney_yim_hesterberg_2004, title={Examination of backfill materials for high-level waste repository}, volume={9}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-4544384119&partnerID=MN8TOARS}, number={4}, journal={Technology}, author={McKinney, D.S. and Yim, M.-S. and Hesterberg, D.}, year={2004}, pages={187–194} }
 @article{beauchemin_hesterberg_nadeau_mcgeer_2004, title={Speciation of hepatic Zn in trout exposed to elevated waterborne Zn using X-ray absorption spectroscopy}, volume={38}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-1442325544&partnerID=MN8TOARS}, DOI={10.1021/es034979a}, abstractNote={The long-term impacts of chronic metal exposure for aquatic biota are not well understood, partly due to a lack of understanding of metal speciation within tissues. The objective of this study was to determine hepatic Zn speciation of rainbow trout (Oncorhnychus mykiss) exposed to Zn-enriched water in relation to unexposed (control) fish,through direct analysis of freeze-dried liver samples using synchrotron X-ray absorption spectroscopy (XAS). Juvenile rainbow trout (n=30) were exposed to Zn in a two-step process, 200 microg L(-1) for 14 days, followed by 370 microg L(-1) for 23 days. Thirty other trout were grown in a control treatment (10 microg Zn L(-1)). At the end of the experiment, three liver samples per treatment were collected, freeze-dried, ground, and mixed homogeneously. Although Zn concentration was higher in the Zn-exposed livers than in the control livers (22.32 vs 13.73 mg kg(-1), respectively; p < 0.05), Zn speciation was similar for both groups. Extended X-ray absorption fine structure (EXAFS) spectroscopy indicated that Zn was coordinated to 4 sulfur atoms with an average Zn-S bond distance of 2.31 +/- 0.02 A. Sulfur K-XANES analysis confirmed that S was predominantly in reduced organic form analogous to cysteine. Our results are consistent with previous evidence for Zn(II) bonding to S in metallothionein proteins. These results suggest that the mechanisms for dealing with the extra load of bioaccumulated Zn in high exposure conditions were the same as in the control group.}, number={5}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Beauchemin, S and Hesterberg, D and Nadeau, J and McGeer, JC}, year={2004}, month={Mar}, pages={1288–1295} }
 @article{khare_hesterberg_beauchemin_wang_2004, title={XANES determination of adsorbed phosphate distribution between ferrihydrite and boehmite in mixtures}, volume={68}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-1542291512&partnerID=MN8TOARS}, DOI={10.2136/sssaj2004.4600}, abstractNote={Iron‐ and Al‐(hydr)oxide minerals are important sorbents for retaining PO4 in soils. Our objective was to determine the distribution of adsorbed PO4 between ferrihydrite and boehmite in aqueous mixtures of these minerals. Phosphate was adsorbed in aqueous suspensions up to maximum concentrations of 1860, 850, and 1420 mmol kg−1 for ferrihydrite, boehmite, and 1:1 (by mass) mixtures of these minerals at pH 6. The solids were analyzed as moist pastes using P K‐XANES (X‐ray absorption near edge structure) spectroscopy. The adsorption isotherm for the mixed‐mineral suspensions could essentially be described as a linear combination of Freundlich isotherm models for each single‐mineral system, indicating negligible mineral interactive effects on PO4 adsorption in the mixtures. X‐ray absorption near edge structure spectra for PO4 adsorbed on ferrihydrite or in ferrihydrite/boehmite mixtures showed a pre‐edge feature at approximately 2146 eV that was absent in boehmite systems. Linear combination fitting of the pre‐edge region of XANES spectra for mixtures with average spectra for PO4 adsorbed on boehmite or ferrihydrite alone, indicated that 59 to 97% of the PO4 was adsorbed on ferrihydrite in the mixtures. With increasing concentration of adsorbed PO4 in the mineral mixtures, the concentration adsorbed on the ferrihydrite component increased linearly. Phosphate distribution trends in the mixtures suggested an affinity preference for ferrihydrite at the lowest adsorbed PO4 concentration (100 mmol kg−1 minerals), no affinity preference for either mineral at intermediate concentrations (200 to 600 mmol PO4 kg−1), and the possibility of a surface precipitate involving Al at the highest concentration (1300 mmol PO4 kg−1).}, number={2}, journal={Soil Science Society of America Journal}, author={Khare, N. and Hesterberg, Dean and Beauchemin, S. and Wang, S. L.}, year={2004}, pages={460–469} }
 @article{devolder_brown_hesterberg_pandya_2003, title={Metal bioavailability and speciation in a wetland tailings repository amended with biosolids compost, wood ash, and sulfate}, volume={32}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0037952657&partnerID=MN8TOARS}, DOI={10.2134/jeq2003.0851}, abstractNote={Lead poisoning of waterfowl from direct ingestion of wetland mine tailings has been reported at the Coeur d'Alene River basin in Idaho. A greenhouse study was conducted to evaluate the effects of surface applications of amendments on lead bioavailability in the tailings. Treatments included sediment only, and sediment with three different surface amendments: (i) biosolids compost plus wood ash, (ii) compost + wood ash + a low SO2−4 addition as K2SO4, and (iii) compost + wood ash + a high SO2−4 addition. Measured variables included growth and tissue Pb, Zn, and Cd concentration of arrowhead (Sagittaria latifolia Willd.) and cattail (Typha latifolia L.) and soil pH, redox potential (Eh), pore water Pb, Pb speciation by X-ray absorption spectroscopy, and in vitro Pb bioavailability. The compost + ash amendment alleviated phytotoxicity for both plant species. Bioavailability of Pb as measured by a rapid in vitro extract decreased by 24 to 34% (over control) in the tailings directly below the amendment layer in the compost + SO4 treatments. The ratio of acid volatile sulfide (AVS) to simultaneously extracted metals (SEM) also indicated a reduction in Pb bioavailability (1:40 control, 1:20 compost, 1:8 compost + low SO4, and 1:3 compost + high SO4). Extended X-ray adsorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopy data indicated that lead sulfide was greater after 99 d in the treatments that included additions of sulfate. These results indicated that, under reducing conditions, surface amendments of compost + wood ash (with or without sulfate) decreased the bioavailability of Pb in metal-contaminated mine tailings.}, number={3}, journal={Journal of Environmental Quality}, author={DeVolder, P. S. and Brown, S. L. and Hesterberg, Dean and Pandya, K.}, year={2003}, pages={851–864} }
 @article{beauchemin_hesterberg_chou_beauchemin_simard_sayers_2003, title={Speciation of phosphorus in phosphorus-enriched agricultural soils using X-ray absorption near-edge structure spectroscopy and chemical fractionation}, volume={32}, ISSN={["0047-2425"]}, DOI={10.2134/jeq2003.1809}, abstractNote={ABSTRACT}, number={5}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Beauchemin, S and Hesterberg, D and Chou, J and Beauchemin, M and Simard, RR and Sayers, DE}, year={2003}, pages={1809–1819} }
 @article{beauchemin_hesterberg_chou_beauchemin_simard_sayers_2003, title={Speciation of phosphorus in phosphorus-enriched agricultural soils using X-ray absorption near-edge structure spectroscopy and chemical fractionation}, volume={32}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0141483569&partnerID=MN8TOARS}, number={5}, journal={Journal of Environmental Quality}, author={Beauchemin, S. and Hesterberg, D. and Chou, J. and Beauchemin, M. and Simard, R.R. and Sayers, D.E.}, year={2003}, pages={1809–1819} }
 @article{nelson_mikkelsen_hesterberg_2003, title={Struvite precipitation in anaerobic swine lagoon liquid: effect of pH and Mg : P ratio and determination of rate constant}, volume={89}, ISSN={["0960-8524"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0038182035&partnerID=MN8TOARS}, DOI={10.1016/S0960-8524(03)00076-2}, abstractNote={Because of increased concern about surface water eutrophication from nutrient-enriched agricultural runoff, many swine producers are encouraged to decrease application rates of waste-based P. Precipitation and subsequent removal of magnesium ammonium phosphate (MgNH(4)PO(4) x 6H(2)O), commonly known as struvite, is a promising mechanism for N and P removal from anaerobic swine lagoon effluent. The objectives of this research were to (i) quantify the effects of adjusting pH and Mg:P ratio on struvite precipitation and (ii) determine the rate constant pH effect for struvite precipitation in anaerobic swine lagoon liquid. Concentrations of PO(4)-P in liquid from two anaerobic swine lagoons were determined after 24 h of equilibration for a pH range of 7.5-9.5 and Mg:P ratios between 1:1 and 1.6:1. Struvite formation reduced the PO(4)-P concentration in the effluents to as low as 2 mgl(-1). Minimum concentrations of PO(4)-P occurred between pH 8.9 and 9.25 at all Mg:P ratios. Struvite precipitation decreased PO(4)-P concentrations by 85% within 20 min at pH 9.0 for an initial Mg:P ratio of 1.2:1. The rate of PO(4)-P decrease was described by a first-order kinetic model, with rate constants of 3.7, 7.9, and 12.3 h(-1) at pH 8.4, 8.7 and 9.0 respectively. Our results indicate that induced struvite formation is a technically feasible method to remove N and P from swine lagoon liquid and it may allow swine producers to recover nutrients for off-farm sale.}, number={3}, journal={BIORESOURCE TECHNOLOGY}, author={Nelson, NO and Mikkelsen, RL and Hesterberg, DL}, year={2003}, month={Sep}, pages={229–236} }
 @article{appelboom_chescheir_skaggs_hesterberg_2002, title={Management practices for sediment reduction from forest roads in the coastal plains}, volume={45}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0346034829&partnerID=MN8TOARS}, DOI={10.13031/2013.8529}, abstractNote={Sediment has been identified as one of the most important non-point source pollutants of surface waters. In forested areas, the predominant source of sediment is from the construction and maintenance of access roads, which contribute as much as 90% of the total eroded sediments. Seven different road management practices were studied to determine their effectiveness in reducing sediment production from forest roads on nearly flat lands in the lower coastal plains of North Carolina. One practice utilized a continuous berm along the roadside, while the other six practices had a non-continuous berm with different combinations of road surface gravel and roadside vegetative strips. Runoff samples collected during eleven different rainfall events of varying intensity and duration were analyzed for sediment content. The rainfall amount, intensity, infiltration, and antecedent rainfall conditions were combined into a single energy rating to assist in the overall analysis. The results of the study showed that a continuous berm maintained along the edge of a forest road can reduce total sediment loss by an average of 99% compared to the same type road without the presence of a continuous berm. When a continuous berm is not present, graveling the road surface can reduce the total loss of sediment from roads by an average of 61% compared to a non-graveled road surface. A 90 cm wide grass strip on the edge of the driving surface can reduce total sediment loss by an average of 56% compared to a road without a grass strip.}, number={2}, journal={Transactions of the ASAE}, author={Appelboom, T. W. and Chescheir, G. M. and Skaggs, R. W. and Hesterberg, Dean}, year={2002}, pages={337–344} }
 @article{beauchemin_hesterberg_beauchemin_2002, title={Principal component analysis approach for modeling sulfur K- XANES spectra of humic acids}, volume={66}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036154663&partnerID=MN8TOARS}, DOI={10.2136/sssaj2002.8300}, abstractNote={Quantitative application of x‐ray absorption near edge structure (XANES) spectroscopy to soils and other geochemical systems requires a determination of the proportions of multiple chemical species that contribute to the measured spectrum. Two common approaches to fitting XANES spectra are spectral deconvolution and least‐squares linear combination fitting (LCF). The objective of this research was to evaluate principal component analysis (PCA) coupled with target transformation to model S K‐XANES spectra of humic acid samples, and to compare the results with least‐squares LCF. Principal component analysis provided a statistical basis for choosing the number of standard species to include in the fitting model. Target transformation identified which standards were statistically more likely to explain the spectra of the humic acid samples. The selected standards and the scaling coefficients obtained by the PCA approach deviated by ≤6 mol% from results obtained by performing LCF using a large number of binary, ternary, and quaternary combinations of seven S standards. Because no energy shift is allowed in the PCA approach, fitting may be refined, when appropriate, by using afterwards a least‐squares method that includes energy offset parameters. Statistical ranking of the most likely standard spectra contributing to the unknown spectra enhanced LCF by reducing the analysis to a smaller set of standard spectra. The PCA approach is a valuable complement to other spectral fitting techniques as it provides statistical criteria that improve insight to the data, and lead to a more objective approach to fitting.}, number={1}, journal={Soil Science Society of America Journal}, author={Beauchemin, S. and Hesterberg, Dean and Beauchemin, M.}, year={2002}, pages={83–91} }
 @article{zhang_brady_arthur_zhou_sawyer_hesterberg_2001, title={Adsorption of barium(II) on montmorillonite: an EXAFS study}, volume={190}, ISSN={["0927-7757"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035888451&partnerID=MN8TOARS}, DOI={10.1016/S0927-7757(01)00592-1}, abstractNote={Migration of radioactive radium, 226Ra, in soil is an environmental concern, especially in areas adjacent to uranium processing facilities. Barium(II), as Ba2+, was used as a Ra analog and reacted with a Na-montmorillonite to obtain mechanistic insights into the interaction of Ra with soil matrices. The majority of sorbed Ba is associated with the permanently charged surface sites on the montmorillonite basal surface. This is indicated by the facts that (1) sorption of Ba(II) on montmorillonite is not highly sensitive to solution pH, although an increase of sorption was observed at higher pH values; and (2) displacement of sorbed Ba increased with increased NaNO3 concentration. As demonstrated by EXAFS, a small fraction of Ba also adsorbed on the montmorillonite edge, forming an inner-sphere surface complex through sharing of oxygen atom(s) from deprotonated –OH group of the Al octahedral layer. The EXAFS measured distances between Ba and O at the first shell, and Ba and Al of the second shell are 2.7–2.8 and 3.7–3.9 Å, respectively, consistent with the results from geometry of a inner-sphere complex at the edge site. Results from bulk experiments and spectroscopic analysis suggest a co-existence of outer- and inner-sphere surface complexes for Ba sorbed to the montmorillonite surface.}, number={3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Zhang, PC and Brady, PV and Arthur, SE and Zhou, WQ and Sawyer, D and Hesterberg, DA}, year={2001}, month={Oct}, pages={239–249} }
 @article{hesterberg_chou_hutchison_sayers_2001, title={Bonding of Hg(II) to reduced organic, sulfur in humic acid as affected by S/Hg ratio}, volume={35}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035387905&partnerID=MN8TOARS}, DOI={10.1021/es001960o}, abstractNote={Organic matter is an important sorbent of heavy metals in soils and sediments. The heterogeneity of organic matter, including the presence of various reactive O-, N-, and S-bearing ligands, makes it difficult to precisely characterize the nature of metal-ligand binding sites. The objective of this research was to characterize the extent and nature of Hg(II) bonding with reduced organic S in soil organic matter. Sulfur-rich humic acid (0.7 +/- 0.1 mol of S kg-1) was extracted from samples of surface soil from a marine wetland. Synchrotron X-ray absorption near-edge structure (XANES) analysis at the S K edge indicated that 70 +/- 3 mol % of the organic S was in a reduced oxidation state. Aqueous solutions containing 2 mmol of Hg kg-1, 0.1 M NaNO3, and humic acid added at various S/Hg molar ratios at pH 5.60 +/- 0.02 were characterized using extended X-ray absorption fine structure (EXAFS) spectroscopy at the Hg LIII edge. Spectral fitting showed that as the total S/Hg ratio increased from 0.6 to 5.6 (reduced S/Hg of 0.4-4.0), the fraction of Hg-S bonding relative to Hg-O (or Hg-N) bonding increased from 0.4 to 0.9. Results demonstrated preferential bonding of Hg(II) to reduced organic S sites and indicated that multiple sulfur ligands were coordinated with Hg2+ ions at high S/Hg ratios, which corresponded to low levels of complexed Hg(II).}, number={13}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Hesterberg, D and Chou, JW and Hutchison, KJ and Sayers, DE}, year={2001}, month={Jul}, pages={2741–2745} }
 @article{ryan_zhang_hesterberg_chou_sayers_2001, title={Formation of chloropyromorphite in a lead-contaminated soil amended with hydroxyapatite}, volume={35}, ISSN={["0013-936X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035884175&partnerID=MN8TOARS}, DOI={10.1021/es010634l}, abstractNote={Conversion of soil Pb to pyromorphite [Pb5(PO4)3Cl] was evaluated by reacting a Pb contaminated soil collected adjacent to a historical smelter with hydroxyapatite [Ca5(PO4)3OH]. In a dialysis experiment where the soil and hydroxyapatite solids were placed in separate dialysis bags suspended in 0.01 M NaNO3 solution a crystalline precipitate, identified as chloropyromorphite, formed on the dialysis membrane containing the soil. The aqueous composition of the solution indicated that dissolution of solid-phase soil Pb was the rate-limiting step for pyromorphite formation. Addition of hydroxyapatite to the soil caused a decrease in each of the first four fractions of sequential extractable Pb and a 35% increase in the recalcitrant extraction residue. After a 240-d incubation at field-moisture content there was a further increase in the recalcitrant extraction residue fraction of the hydroxyapatite-amended soil to 45% of the total soil Pb. The increase in the extraction residue fraction in the hydroxyapatite amended 0-d incubated soil as compared to the control soil illustrates that the chemical extraction procedure itself caused changes in extractability. Thus, the chemical extraction procedure cannot easily be utilized to confirm changes occurring in amended soils. The further increase after the 240-d incubation implies that the reaction also occurs in the soil during incubation. Extended X-ray absorption fine structure (EXAFS) spectroscopy indicated that after the 240-d incubation the hydroxyapatite treatment caused a change in the average, local molecular bonding environment of soil Pb. Low-temperature EXAFS spectra (chi data and radial structure functions--RSFs) showed a high degree of similarity between the chemical extraction residue and synthetic pyromorphite, providing additional evidence that the change of soil Pb to pyromorphite is possible by simple amendments of hydroxyapatite to soil.}, number={18}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Ryan, JA and Zhang, PC and Hesterberg, D and Chou, J and Sayers, DE}, year={2001}, month={Sep}, pages={3798–3803} }
 @article{alcacio_hesterberg_chou_martin_beauchemin_sayers_2001, title={Molecular scale characteristics of Cu(II) bonding in goethite-humate complexes}, volume={65}, ISSN={["1872-9533"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035010875&partnerID=MN8TOARS}, DOI={10.1016/S0016-7037(01)00546-4}, abstractNote={—Interactions between oxide minerals and natural organic matter affect metal adsorption properties of mineral surfaces, but the mechanisms of metal bonding are not well understood. Extended X-ray absorption fine structure (EXAFS) spectroscopy analyses were performed on aqueous pastes containing Cu(II) and goethite (α-FeOOH) with humic acid adsorbed at 0, 14, 28, 57, 88, 216, and 236 g kg−1 goethite, and with aqueous suspensions of humic acid only. Analyses were conducted at the Cu K edge with 40 mmol Cu(II) kg−1 goethite or 2 mmol Cu(II) kg−1 suspension for the humic acid system. Samples were equilibrated at pH 5.6 in a 0.1 M NaNO3 background electrolyte. For all systems, analysis of EXAFS results suggests that Cu(II) is present in a distorted octahedral configuration containing four short equatorial (1.94–1.97 Å) and two longer axial bonds with oxygen. When the concentration of adsorbed humic acid on goethite was increased from 0 to 28 g kg−1, the axial Cu-O bond length decreased to 2.24 ± 0.03 Å, which was less than for individual humic acid (2.32 ± 0.02 Å) or goethite (2.29 ± 0.03 Å) samples. The apparent decrease in the axial Cu-O bond length was attributed to a decrease in the ligand field splitting energy. When humic acid ligands replace equatorial water molecules in the Cu(II) coordination sphere, a weaker ligand field strength occurs. For absorbed humic acid up to 88 g kg−1 goethite, second-shell iron neighbors were observed between 3.17 and 3.20 Å, suggesting that Cu(II) was bonded on average to both inorganic (goethite) and organic (humic acid) functional groups. In addition, derivative X-ray absorption near edge structure (XANES) spectra for Cu(II) on goethite–humate complexes (<88 g kg−1) were poorly fit by use of a linear combination of spectra for Cu(II) on goethite or humate alone. At humate concentrations between 216 and 236 g kg−1 goethite, second-shell iron neighbors could not be identified, and the Cu-Oaxial distance (2.32 ± 0.02 Å) and derivative XANES spectra strongly resembled that of Cu(II) adsorbed to humate only. Analysis of the XANES and EXAFS data suggested that Cu(II) was bonded on average to both inorganic and organic functional groups as a type A ternary complex at lower levels of adsorbed humate, and to organic groups as a type B complex at higher levels.}, number={9}, journal={GEOCHIMICA ET COSMOCHIMICA ACTA}, author={Alcacio, TE and Hesterberg, D and Chou, JW and Martin, JD and Beauchemin, S and Sayers, DE}, year={2001}, month={May}, pages={1355–1366} }
 @article{fichtner_hesterberg_shew_2001, title={Nonphytotoxic aluminum-peat complexes suppress Phytophthora parasitica}, volume={91}, ISSN={["1943-7684"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035156475&partnerID=MN8TOARS}, DOI={10.1094/PHYTO.2001.91.11.1092}, abstractNote={ Amendment of peat-based potting media with Al2(SO4)3 suppresses damping-off of Vinca (Catharanthus roseus) caused by Phytophthora parasitica. The species of aluminum (Al) responsible for disease suppression have not been identified. The objective of this study was to determine the effects of amount and pH of Al2(SO4)3 amendment solutions on survival of P. parasitica. In separate experiments, peat was amended with Al2(SO4)3 solutions adjusted to pH 4 or 6 at either 0.0158 or 0.0079 g of Al per gram of peat. Amended peat was placed in Büchner funnels maintained at -2.5 kPa matric potential. Peat was infested with P. parasitica by placing zero, two, or five colonized Vinca leaf disks in each funnel, and 15 Vinca seeds were placed in each funnel. After 24 h, the matric potential was brought to 0 kPa to induce zoospore release and returned to -2.5 kPa after 24 h. Pathogen populations and stand counts were assessed after 2-week incubation. Al amendment solutions at both pH 4 and 6 reduced pathogen populations at 0.0158 g of Al per gram of peat. Solutions at pH 4 reduced pathogen populations by more than 90% at both inoculum levels; amendment solutions at pH 6 reduced populations by 95% at the low inoculum level and 65% at the high inoculum level. The prevalence of Al(OH)2+ in peat amended with Al2(SO4)3 solution at pH 6 suggests that ions other than Al3+ may be responsible for pathogen suppression. Based on the difference in chemical conditions of Al-amended peat and suppressive mineral soils, the mechanism of Al-mediated suppression of plant pathogens is speculated to be different in the two systems. Peat containing Al-peat complexes was chemically suppressive to P. parasitica and may confer Al-mediated suppression of plant pathogens with a nonphytotoxic form of Al. }, number={11}, journal={PHYTOPATHOLOGY}, author={Fichtner, EJ and Hesterberg, DL and Shew, HD}, year={2001}, month={Nov}, pages={1092–1097} }
 @article{hutchison_hesterberg_chou_2001, title={Stability of reduced organic sulfur in humic acid as affected by aeration and pH}, volume={65}, ISSN={["0361-5995"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034977841&partnerID=MN8TOARS}, DOI={10.2136/sssaj2001.653704x}, abstractNote={Reduced S groups in soil organic matter (OM) play an important role in the complexation of heavy metals. These complexation reactions are often studied using the humic acid component of OM. The objective of our study was to determine the effect of pH on humic acid yield and the effect of pH and exposure to O2 on the oxidation of reduced organic S. Humic acid was extracted at pH levels between 11.5 and 13.0 from a soil collected from a salt marsh. Also, aqueous samples of humic acid at different pH levels were aspirated with CO2‐free air for 4 or 44 h. X‐ray absorption near‐edge structure (XANES) spectroscopy was used to determine changes in S oxidation states for the various treatments. With increasing pH, the yield of humic acid increased from 1.3 to 4.6 g humic acid kg−1 soil, and the total S in these samples was 24 ± 1 g kg −1 humic acid. Linear‐combination fitting of XANES spectra showed that all of these humic acid samples contained ≈70% (mol/mol) reduced S (modeled as benzyl disulfide) and 30% (mol/mol) oxidized S (modeled as sulfonate and ester sulfate). For humic acid exposed to aeration for 4 h at pH levels between 11.5 and 13.0, reduced organic S was oxidized only at pH 13.0 (15% [mol/mol] of total S). Samples exposed to aeration for 44 h between pH 3.5 and 12.4 showed no detectable change in reduced organic S.}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Hutchison, KJ and Hesterberg, D and Chou, JW}, year={2001}, pages={704–709} }
 @article{vos_hesterberg_raats_2000, title={Nitrate leaching in a tile-drained silt loam soil}, volume={64}, ISSN={["0361-5995"]}, DOI={10.2136/sssaj2000.642517x}, abstractNote={Nitrate (NO3) leaching was studied for a winter leaching period in a layered calcareous silt loam with tile‐drains at about 1‐m depth and 12‐m spacing. Groundwater levels, drain discharge rates, and NO3 concentrations in the drainage water were monitored, and the soil hydraulic characteristics were measured for the different soil layers. The data were interpreted using the two‐dimensional water flow and solute transport model SWMS_2D. This model uses Darcy's law for water flow and the convection–dispersion equation for solute transport for both the saturated and unsaturated zones. A nitrogen‐production term of 39 kg N ha−1 was used to account for the net N mineralization in the topsoil during the leaching period. The model was calibrated by varying the hydraulic conductivity at saturation (Ks) for the different soil layers, using the measured groundwater level–drain discharge rate relationship as calibration target. Peaks in NO3 concentrations in the drainage water are well explained by the temporal two‐dimensional behavior of convective transport. Measured NO3 leaching was 11 kg N ha−1 yr−1 and simulated NO3 leaching was 15 kg N ha−1 yr−1 in the relatively dry winter leaching period 1991–1992. The two‐dimensional transport model SWMS_2D is a useful tool to evaluate the relative effects of management practices to reduce N leaching.}, number={2}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Vos, JA and Hesterberg, D and Raats, PAC}, year={2000}, pages={517–527} }
 @article{de vos_hesterberg_raats_2000, title={Nitrate leaching in a tile-drained silt loam soil}, volume={64}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034162360&partnerID=MN8TOARS}, number={2}, journal={Soil Science Society of America Journal}, author={De Vos, J.A. and Hesterberg, D. and Raats, P.A.C.}, year={2000}, pages={517–527} }
 @article{williams_nelson_hesterberg_2000, title={Phosphate and potassium retention and release during chrysanthemum production from precharged materials: I. Alumina}, volume={125}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0033733306&partnerID=MN8TOARS}, number={6}, journal={Journal of the American Society for Horticultural Science}, author={Williams, K.A. and Nelson, P.V. and Hesterberg, D.}, year={2000}, pages={748–756} }
 @inproceedings{nelson_mikkelsen_hesterberg_2000, title={Struvite formation to remove phosphorus from anaerobic swine lagoon effluent}, number={2000}, booktitle={Animal, agriculture and food processing waste: 8th Symposium: American Society of Agriculture Engineers, 2000}, publisher={St. Joseph, Michigan: American Society of Agricultural Engineers}, author={Nelson, N. O. and Mikkelsen, R. L. and Hesterberg, D. L.}, year={2000}, pages={18–26} }
 @article{oh_hesterberg_nelson_1999, title={Comparison of phosphate adsorption on clay minerals for soilless root media}, volume={30}, ISSN={["0010-3624"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032961768&partnerID=MN8TOARS}, DOI={10.1080/00103629909370243}, abstractNote={Abstract The greenhouse industry aims to decrease phosphate discharge to help reduce eutrophication of surface waters, to reduce fertilizer consumption, and to maintain a more constant level of plant‐available phosphate. Iron and aluminum oxides and some aluminosilicate minerals are efficient sorbents for phosphate. The phosphate adsorption characteristics of synthetic hematite (α‐Fe2O3), goethite (α‐FeOOH), and allophane (Si3Al4O12 nH2O), and a commercial alumina (A12O3) were evaluated to determine their potential for reducing phosphate leaching from soilless root media. The pH dependence of phosphate adsorption and maximum adsorption capacities were determined by reacting each mineral with various levels of phosphate between pH 4.0 and 9.0 in a 10 mM potassium chloride (KCl) background solution. Adsorbed phosphate was determined by loss from solution. Adsorption envelopes (adsorbed phosphate versus pH) showed a decrease in phosphate adsorption with increasing pH, particularly for alumina and allophane, ...}, number={5-6}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Oh, YM and Hesterberg, DL and Nelson, PV}, year={1999}, pages={747–756} }
 @article{colberg_saez_grant_hutchison_hesterberg_1999, title={Dynamic hydration of phospholipid films in aqueous environments}, volume={151}, ISSN={["0927-7757"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0344267705&partnerID=MN8TOARS}, DOI={10.1016/S0927-7757(98)00842-5}, abstractNote={A dynamic study of the hydration of phospholipid films attached to solid substrates when exposed to liquid water at room temperature is presented. The phospholipids used were 1,2-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine (DPPE), and a modification of DPPE with a fluorescent molecular probe: n-(5-fluoresceinthicarbamoyl)-1,2-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine, triethylammonium salt (FITC-DPPE). Three different experimental techniques were used: rates of hydration were measured by depositing the phospholipid film on a quartz crystal microbalance (QCM), total internal reflection fluorescence (TIRF) studies were carried out with FITC-DPPE films deposited on the internal surface of a cylindrical quartz tube, and X-ray diffraction analysis was used to determine possible changes of the film’s crystalline structure during hydration. The DPPE films exhibited different successive hydration stages: within the first 2 h, the films uniformly hydrate towards a limiting water uptake (short-time behavior); however, at one point, hydration rates suddenly increase and the hydration process continues for longer periods of time, of the order of 24 h. No evidence of change in the film crystalline structure was found when dry and hydrated DPPE films were analyzed by wide-angle X-ray diffraction. The FITC-DPPE films showed a completely different hydration pattern: water uptake reached a maximum value at short times and then decreased continuously until an asymptotic value was reached. The TIRF results on FITC-DPPE films show that the evolution of fluorescence with time closely resembles the hydration results obtained in the QCM. This is attributed to the self quenching occurring in the phospholipid films.}, number={3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Colberg, MT and Saez, AE and Grant, CS and Hutchison, K and Hesterberg, D}, year={1999}, month={Jul}, pages={483–495} }
 @article{zhou_hesterberg_hansen_hutchison_sayers_1999, title={Stability of copper sulfide in a contaminated soil}, volume={6}, ISSN={["0909-0495"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0033417334&partnerID=MN8TOARS}, DOI={10.1107/S0909049599001776}, abstractNote={Because of their low solubility under reduced soil conditions, metal sulfides may decrease the toxicity of heavy-metal contaminants. Periodic variations in soil moisture may expose reduced soils to oxidizing conditions that are conducive to oxidative dissolution of metal sulfides. Using EXAFS spectroscopy, we determined the proportion of copper sulfide in soil samples before and after exposure to more oxidizing conditions for 35 days at pH 6.6 or 7.6. The samples were collected from the reduced zone (47 to 73 and 73 to 101 cm depth) of a contaminated soil and contained about 1,700 mg Cu/kg. In both the original and the treated soil samples, we detected only Cu-S bonding in the first shell, indicating that the soil samples were not oxidized to Cu-O bonding during the treatment.}, number={1999 May 1}, journal={JOURNAL OF SYNCHROTRON RADIATION}, author={Zhou, WQ and Hesterberg, D and Hansen, PD and Hutchison, KJ and Sayers, DE}, year={1999}, month={May}, pages={630–632} }
 @article{hesterberg_zhou_hutchison_beauchemin_sayers_1999, title={XAFS study of adsorbed and mineral forms of phosphate}, volume={6}, ISSN={["0909-0495"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0033438322&partnerID=MN8TOARS}, DOI={10.1107/S0909049599000370}, abstractNote={The solubility of inorganic phosphorus in soils is regulated by surface-adsorbed phosphate or phosphate minerals. The objective of this study was to determine whether different phosphate species of relevance to soils showed distinguishing XAFS spectral features. Phosphorus KXANES spectra for Fe-phosphates were characterized by a unique pre-edge feature near -3 eV (relative energy) that increased in intensity with increasing mineral crystallinity and was very weak for phosphate adsorbed on goethite. Spectra of Ca-phosphates and a soil sample exhibited a distinct shoulder on the high-energy side of the absorption edge. Spectra of Al-phosphates were characterized by a weak pre-edge feature at -1 eV.}, number={1999 May 1}, journal={JOURNAL OF SYNCHROTRON RADIATION}, author={Hesterberg, D and Zhou, WQ and Hutchison, KJ and Beauchemin, S and Sayers, DE}, year={1999}, month={May}, pages={636–638} }
 @article{hesterberg_1998, title={Biogeochemical cycles and processes leading to changes in mobility of chemicals in soils}, volume={67}, ISSN={["1873-2305"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0031955778&partnerID=MN8TOARS}, DOI={10.1016/S0167-8809(97)00110-2}, abstractNote={There is a general lack of long-term field research showing the environmental fate of soil contaminants after agricultural land is converted to other uses. One concern is that long-term changes in soil properties induced by an alternative land use might cause a non-linear increase in the solubility and mobility of soil chemical contaminants. If a fairly rapid increase in contaminant mobility is delayed for years, then this event may be difficult to predict and to control. To help provide insights to long-term fate of soil contaminants, this paper gives an overview of some factors controlling their solubility and mobility. Because of their indefinite residence time in soils, heavy metals and other trace elements input to agricultural lands with soil amendments may pose the greatest (albeit undetermined) long-term threat. Certain macronutrients, especially N and P, and organic pesticides may have shorter-term detrimental effects on water quality and the environment. Important properties influencing soil contaminant solubility and mobility are the type of contaminant (e.g., heavy metal cation, oxyanion, pesticide), soil matrix composition (e.g., mineralogy and organic matter content), soil heterogeneity, pH, redox potential, and variations in dissolved organic matter concentration. By understanding the mechanisms of contaminant binding in the soil in relation to these properties, the long-term fate of contaminants is more predictable.}, number={2-3}, journal={AGRICULTURE ECOSYSTEMS & ENVIRONMENT}, author={Hesterberg, D}, year={1998}, month={Feb}, pages={121–133} }
 @article{shafer_blum_horton_hesterberg_1998, title={Biomass of tomato seedlings exposed to an allelopathic phenolic acid and enriched atmospheric carbon dioxide}, volume={106}, ISSN={["0049-6979"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032145076&partnerID=MN8TOARS}, DOI={10.1023/A:1004944731826}, number={1-2}, journal={WATER AIR AND SOIL POLLUTION}, author={Shafer, SR and Blum, U and Horton, SJ and Hesterberg, DL}, year={1998}, month={Aug}, pages={123–136} }
 @article{przepiora_hesterberg_parsons_gilliam_cassel_faircloth_1998, title={Field evaluation of calcium sulfate as a chemical flocculant for sedimentation basins}, volume={27}, ISSN={["0047-2425"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032076630&partnerID=MN8TOARS}, DOI={10.2134/jeq1998.00472425002700030026x}, abstractNote={Abstract}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Przepiora, A and Hesterberg, D and Parsons, JE and Gilliam, JW and Cassel, DK and Faircloth, W}, year={1998}, pages={669–678} }
 @article{colberg_carnes_saez_grant_hutchinson_hesterberg_1998, title={Hydration and removal of supported phospholipid films in aqueous surfactant solutions}, volume={327}, ISSN={["0040-6090"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032141167&partnerID=MN8TOARS}, DOI={10.1016/s0040-6090(98)00638-5}, abstractNote={Dynamic studies of the hydration and removal of phospholipid films attached to solid substrates were performed. The phospholipids used were 1,2-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine (DPPE), and a modification of DPPE containing a fluorescent molecular probe: n-(5-fluoresceinthicarbamoyl)-1,2-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine, triethylammonium salt (FITC-DPPE). The phospholipid films were exposed to water and aqueous solutions of the anionic surfactant sodium dodecyl sulfate (SDS). The film mass was determined as a function of time by means of a quartz crystal microbalance (QCM). The crystalline structure of the film during the hydration process was analyzed by means of wide-angle X-ray diffraction. At low surfactant concentrations (below 20% of the critical micelle concentration (CMC)), the presence of surfactant increased the hydration rate of the film, as well as its maximum water uptake. At surfactant concentrations as low as 50% of the CMC, competitive hydration and removal of the phospholipid film were observed. X-Ray diffraction measurements show that the crystal structure of the DPPE films did not change significantly upon exposure to water and surfactant solutions. In contrast, FITC-DPPE films exhibited changes in the long-range spacing of their crystalline structure upon hydration.}, number={1998 Aug. 31}, journal={THIN SOLID FILMS}, author={Colberg, MT and Carnes, K and Saez, AE and Grant, CS and Hutchinson, K and Hesterberg, D}, year={1998}, month={Aug}, pages={247–251} }
 @book{hesterberg_1998, title={Reduction of turbidity in sedimentation basins}, number={1998 Apr. 1}, journal={Report (Water Resources Research Institute of the University of North Carolina)}, institution={Raleigh, NC: University of North Carolina Water Resources Research Institute}, author={Hesterberg, D.}, year={1998} }
 @article{przepiora_hesterberg_parsons_gilliam_cassel_faircloth_1997, title={Calcium sulfate as a flocculant to reduce sedimentation basin water turbidity}, volume={26}, ISSN={["0047-2425"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0031278959&partnerID=MN8TOARS}, DOI={10.2134/jeq1997.00472425002600060021x}, abstractNote={Abstract}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Przepiora, A and Hesterberg, D and Parsons, JE and Gilliam, JW and Cassel, DK and Faircloth, W}, year={1997}, pages={1605–1611} }
 @article{kretzschmar_hesterberg_sticher_1997, title={Effects of adsorbed humic acid on surface charge and flocculation of kaolinite}, volume={61}, ISSN={["0361-5995"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0030613847&partnerID=MN8TOARS}, DOI={10.2136/sssaj1997.03615995006100010016x}, abstractNote={Abstract}, number={1}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Kretzschmar, R and Hesterberg, D and Sticher, H}, year={1997}, pages={101–108} }
 @inproceedings{wang_hesterberg_zhou_sayers_robarge_1997, title={Extended x-ray absorption fine structure study of mercury speciation in a flood plain soil}, number={1997}, booktitle={Contaminated soils: 3rd International Conference on the Biogeochemistry of Trace Elements, Paris (France), May 15-19, 1995}, publisher={Paris: INRA Editions}, author={Wang, Z. and Hesterberg, D. and Zhou, W. and Sayers, D. E. and Robarge, W. P.}, year={1997} }
 @article{hesterberg_sayers_zhou_plummer_robarge_1997, title={X-ray absorption spectroscopy of lead and zinc speciation in a contaminated groundwater aquifer}, volume={31}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0031260138&partnerID=MN8TOARS}, DOI={10.1021/es970077w}, abstractNote={The formation of insoluble metal sulfides in the environment may reduce the mobility and bioavailability of heavy metal contaminants and potentially eliminate the need for ex situ remediation of certain hazardous waste sites. To assist in assessing remediation strategies for the Bypass 601 Superfund site, groundwater aquifer samples were analyzed using synchrotron X-ray absorption spectroscopy (XAS) to determine whether lead and zinc sulfides were dominant mineral phases. Moist aquifer solids contained between 150 and 1800 mg of Pb/kg and between 100 and 250 mg of Zn/kg. Lead sulfide was not dominant in any of the samples analyzed, including one sample collected from a well in a flood plain that contained 70% of zinc bonded to sulfur, probably as ZnS. This portion of the aquifer had apparently been under reducing conditions. In all other samples, first-shell bonding of Pb and Zn was predominantly to oxygen. Data indicated that PbO, PbCO3, PbSO4, and ZnO were not dominant metal species. The XAS analyses sh...}, number={10}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Hesterberg, D and Sayers, DE and Zhou, WQ and Plummer, GM and Robarge, WP}, year={1997}, month={Oct}, pages={2840–2846} }
 @article{hesterberg_sayers_zhou_robarge_plummer_1997, title={XAFS Characterization of Copper in Model Aqueous Systems of Humic Acid and Illite}, volume={7}, ISSN={1155-4339}, url={http://dx.doi.org/10.1051/jp4:1997253}, DOI={10.1051/jp4:1997253}, abstractNote={Adsorption of heavy metals at mineral surfaces and complexation with reactive organic-matter functional groups are important processes regulating the solubility and fate of soil contaminants. To determine the nature of Cu(II) bonding in complex clay-organic systems, XAFS analyses were conducted on aqueous suspensions containing Cu(II) in various forms: (i) complexed with soil humic acid (HA) at various HA:Cu ratios, (ii) bound to illite, or (iii) bound in a mixture of illite and HA. Spectral features for Cu bound to HA did not depend significantly on the HA:Cu ratio, and average first-shell Cu-O bond lengths were consistently shorter than for the Cu-illite systems. In the mixed clay-organic suspension, Cu bonding was more characteristic to that of Cu bound with HA.}, number={C2}, journal={Le Journal de Physique IV}, publisher={EDP Sciences}, author={Hesterberg, D. and Sayers, D. E. and Zhou, W. and Robarge, W. P. and Plummer, G. M.}, year={1997}, month={Apr}, pages={C2–833-C2–834} }
 @article{sayers_hesterberg_zhou_robarge_plummer_1997, title={XAFS characterization of copper contamination in the unsaturated and saturated zones of a soil profile}, volume={7}, ISSN={["1155-4339"]}, DOI={10.1051/jp4:1997252}, abstractNote={The fate of heavy-metal contaminants in the environment, and the design and success of remediation strategies at hazardous waste sites depend on the chemical speciation of the contaminants. The objective of this study was to determine the molecular-scale chemical form (species) of heavy metals in different zones of a contaminated soil having a shallow ground water table. Copper in the unsaturated surface horizon and the water-saturated and partially-saturated subsurface horizons of a disturbed soil from the lower eastern coastal plain of North Carolina was characterized using XAFS spectroscopy. Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) data showed that the dominant form of Cu(II) bonding ranged from Cu-S in the deeper soil zones to Cu-O in the shallowest zone. The results suggest that the surface and subsurface horizons will respond differently to remediation treatments.}, number={C2}, journal={JOURNAL DE PHYSIQUE IV}, author={Sayers, DE and Hesterberg, D and Zhou, W and Robarge, WP and Plummer, GM}, year={1997}, month={Apr}, pages={831–832} }
 @inproceedings{sayers_hesterberg_zhou_robarge_plummer_1997, title={XAFS characterization of copper contamination in the unsaturated and saturated zones of a soil profile}, volume={7}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0031126012&partnerID=MN8TOARS}, number={2 Part 2}, booktitle={Journal De Physique. IV : JP}, author={Sayers, D.E. and Hesterberg, D. and Zhou, W. and Robarge, W.P. and Plummer, G.M.}, year={1997} }
 @inproceedings{hesterberg_sayers_zhou_robarge_plummer_1997, title={XAFS characterization of copper in model aqueous systems of humic acid and illite}, volume={7}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33750671277&partnerID=MN8TOARS}, number={2 Part 2}, booktitle={Journal De Physique. IV : JP}, author={Hesterberg, D. and Sayers, D.E. and Zhou, W. and Robarge, W.P. and Plummer, G.M.}, year={1997} }
 @article{hesterberg_1993, title={Effects of stopping liming on abandoned agricultural land}, volume={4}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0027843472&partnerID=MN8TOARS}, DOI={10.1002/ldr.3400040409}, abstractNote={It is suggested that stopping liming on agricultural land could lead to a potential chemical time bomb (CTB). the sequence of interrelated events leading to the CTB include the end of liming, perhaps caused by a change in land use, a progressive decrease in soil pH and increased solubility of potentially toxic contaminants that accumulate in soils as a result of agricultural practices. Data are presented on rates of long-term soil acidification and modelled changes in the solubility of some trace metals in soil as a result of acidification. Soil acidification rates depend primarily on acid input rates and the soil's acid neutralizing capacity, possibly limited by neutralization kinetics. Experimental data illustrating this point show that the pH decreased rapidly in a field soil receiving ammonium rather than nitrate fertilizer treatment. on a limed agricultural field that was later abandoned and converted to deciduous woodland, The pH of the 0-23 cm soil layers decreased over 100 years from pH 7 to 4.2. Deeper layers acidified at a slower rate. Thermodynamic model calculations simulating the solubilities of metals in a sandy topsoil showed zinc, cadmium and aluminium solubilities increasing exponentially with decreasing pH, resulting in several-fold solubility increases between pH 5 and 4. These results suggest how metal solubility increases after liming stops. the model pH-solubility relationships depended on the type of metal, The solid phase controlling the solubility, and the amount of metal in the soil if adsorption controlled the solubility. Decreasing pH and the resultant increase in metal solubility expected on abandoned farmland might be managed through techniques such as liming or planting forests of selected tree species.}, number={4}, journal={Land Degradation & Development}, author={Hesterberg, D.}, year={1993}, pages={257–267} }
 @article{hesterberg_page_1993, title={Rheology of sodium and potassium illite suspensions in relation to colloidal stability}, volume={57}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0027595398&partnerID=MN8TOARS}, DOI={10.2136/sssaj1993.03615995005700030012x}, abstractNote={To further understand the colloidal behavior of clay minerals in soils, rheological properties of illite suspensions were investigated and related to colloidal stability. Using a concentric cylinder viscometer to measure shear stress as a function of shear rate, Bingham yield stresses (τB) and plastic viscosities (ηpl) were determined for homoionic Na- and K-saturated illite suspensions varying in pH, NaCIO4 or KCIO4 concentration, and suspended solids concentration. For a given Na or K concentration, τB typically decreased with increasing pH. At a given pH >5.5, both τB and ηpl increased with increasing electrolyte concentration; but for Na-illite, constant values of τB and ηpl were observed at higher electrolyte concentrations. The Na or K concentration yielding the greatest increase in τB or ηpl per unit increase in concentration was usually less than, but correlated with, published critical coagulation concentrations (CCCs) of Na- or K- illite. With increasing solids concentration at pH 7, τB increased curvilinearly for unstable suspensions and linearly for stable suspensions. In light of published models of non-Newtonian flow, data for unstable suspensions at pH 7 suggested that interparticle bonding energy or the number times energy of bonds within flocs was greater for K-illite in 25 mol K m−3 than for Na-illite in 60 mol Na m−3.}, number={3}, journal={Soil Science Society of America Journal}, author={Hesterberg, D. and Page, A.L.}, year={1993}, pages={697–704} }
 @article{hesterberg_bril_del castilho_1993, title={Thermodynamic modeling of zinc, cadmium, and copper solubilities in a manured, acidic loamy-sand topsoil}, volume={22}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0027686546&partnerID=MN8TOARS}, DOI={10.2134/jeq1993.00472425002200040008x}, abstractNote={Soil solution samples collected during a 14-mo period from manured, loamy-sand soil profiles in the Netherlands showed variations in dissolved Zn, Cd, and Cu concentrations of up to two orders of magnitude. To try to account for variations in the dissolved metals, a thermodynamic model was developed for the chemical-equilibrium computer program CHARON. In addition to solution complexation and solid-phase precipitation of inorganic components, the model accounted for metal complexation with dissolved organic carbon (DOC) ligands and with a solid organic matter (OM) exchanger phase [...]}, number={4}, journal={Journal of Environmental Quality}, author={Hesterberg, D. and Bril, J. and Del Castilho, P.}, year={1993}, pages={681–688} }
 @article{japenga_dalenberg_wiersma_scheltens_hesterberg_salomons_1992, title={Effect of liquid animal manure application on the solubilization of heavy metals from soil}, volume={46}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001906112&partnerID=MN8TOARS}, DOI={10.1080/03067319208026994}, abstractNote={Abstract The effect of liquid animal manure on heavy metal solubilization in soil has been studied in the laboratory; three different types of experiments were carried out: 1) aerobic and anaerobic incubation of soil/manure mixtures 2) desorption of heavy metals from soil, as affected by manure liquid fraction 3) gel permeation chromatography of soil/manure aqueous extracts to identify components responsible for heavy metal solubilization. Alf three different approaches showed that complexation involving high molecular weight dissolved organic matter from the soil/manure matrix is (together with pH) the most important driving force for heavy metal solubilization. As a consequence, chemical and microbial processes (e.g. nitrification) that influence dissolved organic matter concentrations in the soil solution, determine the degree of heavy metal solubilization in manured soil.}, number={1-3}, journal={International Journal of Environmental Analytical Chemistry}, author={Japenga, J. and Dalenberg, J.W. and Wiersma, D. and Scheltens, S.D. and Hesterberg, D. and Salomons, W.}, year={1992}, pages={25–39} }
 @article{hesterberg_reed_1991, title={Volumetric treatment efficiencies of some commercial clay stabilizers}, volume={6}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0026108455&partnerID=MN8TOARS}, DOI={10.2118/18466-PA}, abstractNote={This paper reports on volumetric treatment efficiencies of three commercially available clay-stabilizer treatments that were evaluated in the laboratory. Rock volume treated per unit chemical volume varied up to three-fold between stabilizers and depended on sandstone mineral properties. The results are valuable for designing clay-stabilizer treatments and maximizing stabilizer cost-effectiveness.}, number={1}, journal={SPE Production Engineering}, author={Hesterberg, Dean and Reed, M.G.}, year={1991}, pages={57–62} }
 @article{hesterberg_page_1990, title={Critical coagulation concentrations of sodium and potassium illite as affected by pH}, volume={54}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0025593031&partnerID=MN8TOARS}, DOI={10.2136/sssaj1990.03615995005400030018x}, abstractNote={Abstract The effects of saturating cation (Na or K) and pH on the critical coagulation concentrations (CCCs) of illite were measured. Flocculation series tests showed that between pH 6 and 11, the time‐invariant CCCs of Na illite increased from 6 to 58 mol Na m −3 ; release of interlayer K was controlled by adding 0.1 mol K m −3 to Na‐illite suspensions. The CCCs of K illite increased from 3 to 14 mol K m −3 over the pH range 6 to 10. The lower CCCs of K illite relative to Na illite were consistent with a higher surface affinity for K. Increasing CCC with increasing pH was explained by charge alterations on the edge surfaces due to surface‐specific proton interactions. A comparison of our Na‐illite CCCs to published Na‐kaolinite and Na‐montmorillonite CCCs revealed a greater pH dependence for Na‐illite and Na‐kaolinite CCCs.}, number={3}, journal={Soil Science Society of America Journal}, author={Hesterberg, D. and Page, A.L.}, year={1990}, pages={735–739} }
 @article{hesterberg_page_1990, title={Flocculation series test yielding time-invariant critical coagulation concentrations of sodium illite}, volume={54}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0025692030&partnerID=MN8TOARS}, DOI={10.2136/sssaj1990.03615995005400030017x}, abstractNote={Abstract Critical coagulation concentrations (CCCs) of Na illite were measured using flocculation series tests. Results consistent with kinetic theories of coagulation showed the effect of coagulation/settling time on the CCC at various pH levels. A general flocculation series test procedure for reference and soil minerals is proposed. This test controls particle‐interaction dynamics and uses a long coagulation time to minimize the effects of variations in particle diffusion rates and solids concentrations, and to yield time‐invariant CCCs. After combining Na illite dispersions with a series of pH‐adjusted, concentrated NaClO 4 solutions, the mineral particles coagulated primarily by Brownian diffusion. To control the release of interlayer K from Na illite, an equilibrium K concentration of 0.1 mol m −3 was added to all suspensions. The CCCs were detected from turbidity measurements taken after various coagulation time intervals. Between 2 and 17 h, CCCs generally decreased with increasing particle‐interaction time; however, CCCs measured after 17 and 36 h were equivalent and time invariant.}, number={3}, journal={Soil Science Society of America Journal}, author={Hesterberg, D. and Page, A.L.}, year={1990}, pages={729–735} }
 @inproceedings{hesterberg_reed_1989, title={Volumetric treatment efficiencies of some commercial clay stabilizers}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0024867183&partnerID=MN8TOARS}, booktitle={Society of Petroleum Engineers of AIME, (Paper) SPE}, author={Hesterberg, D. and Reed, M.G.}, year={1989}, pages={91–100 18466} }
 @article{sposito_levesque_hesterberg_1986, title={Calcium-magnesium exchange on illite in the presence of adsorbed sodium.}, volume={50}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0022928345&partnerID=MN8TOARS}, DOI={10.2136/sssaj1986.03615995005000040015x}, abstractNote={Abstract Binary and ternary cation exchange experiments were performed with Na + , Ca 2+ , and Mg 2+ on Silver Hill illite and on a soil illite suspended in 50 mol m −3 perchlorate at pH 7. The binary experiments indicated no preference for Ca over Mg on the specimen illite, but selectivity for bivalent cations over Na + and for Ca 2+ over Mg 2+ on the soil illite. The ternary exchange data showed that, for both illites, there was no effect of adsorbed Na on the Ca‐Mg exchange isotherm at exchangeable sodium percentages from 0 to 30%, either for freshly‐prepared clay suspensions or for those aged up to 270 d in NaClO 4 . No significant differences in the total adsorbed metal charge ( Q o ) were observed among the binary and ternary exchange experiments, and Q o was independent of the degree of bivalent cation saturation ( E Ca or E Mg ) in the Na → Ca and Na → Mg exchange experiments on the soil illite. The Vanselow selectivity coefficient for Mg → Ca exchange on the soil illite decreased as E Ca increased, showing a plateau near E Ca ≈ 0.6 and dropping to 1.0 as E Ca became equal to 1.0. This behavior was interpreted as evidence for at least two classes of surface complex involving Ca and Mg.}, number={4}, journal={Soil Science Society of America Journal}, author={Sposito, G. and Levesque, C.S. and Hesterberg, D.}, year={1986}, pages={905–909} }
 @article{traina_sposito_hesterberg_kafkafi_1986, title={Effects of ionic strength, calcium, and citrate on orthophosphate solubility in an acidic, montmorillonitic soil.}, volume={50}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0022927570&partnerID=MN8TOARS}, DOI={10.2136/sssaj1986.03615995005000030016x}, abstractNote={Abstract A recent study by the authors of the effects of pH and organic acids on residual orthophosphate solubility in an acidic, montmorillonitic soil (Typic Chromoxererts) was extended to include variations of ionic strength (NaCl background) and Ca 2+ concentration at fixed ionic strength. The objective of the experiments was to elucidate further the mechanism of orthophosphate solubility in a montmorillonitic soil containing exchangeable Al(III) and added citric acid. At ionic strengths between 20 and 100 mol m −3 (NaCl) and Ca 2+ concentrations between 1 and 5 mol m −3 at 20 mol m −3 ionic strength (NaCl background), additions of citric acid at low concentrations (<0.1 mol m −3 ) reduced orthophosphate solubility. The solubility then gradually returned to its value in the absence of added organic acid as the citric acid concentration was increased to 0.6 mol m −3 . The only significant effect of increasing the ionic strength or the Ca 2+ concentration was to decrease orthophosphate solubility at any level of citric acid addition. Orthophosphate‐citric acid interactions in the soil were influenced only quantitatively, probably through the displacement of exchangeable Al(III) by Na + and/or Ca 2+ , by increasing the concentration of these two metal cations in the soil solution.}, number={3}, journal={Soil Science Society of America Journal}, author={Traina, S.J. and Sposito, G. and Hesterberg, D. and Kafkafi, U.}, year={1986}, pages={623–627} }
 @article{traina_sposito_hesterberg_kafkafi_1986, title={Effects of pH and organic acids on orthophosphate solubility in an acidic, montmorillonitic soil.}, volume={50}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0022927967&partnerID=MN8TOARS}, DOI={10.2136/sssaj1986.03615995005000010009x}, abstractNote={Abstract The effects of pH and organic acid addition on residual orthophosphate ( o ‐phosphate) solubility in an acidic, montmorillonitic soil separate suspended in 20 mol NaCl m −3 were investigated. In the absence of added organic acid, the solubility of residual o ‐phosphate in the soil decreased as the pH value was increased from 4 to 7. With o ‐phosphate additions that resulted in low aqueous‐solution o ‐phosphate concentrations, the soil sorbed more o ‐phosphate at pH 7 than at 5.5. The solubility data appeared consistent with the presence of an Al‐phosphate solid whose formation was initiated through the hydrolysis of exchangeable Al 3+ and subsequent reaction of the hydrolytic product with o ‐phosphate in aqueous solution. Additions of citric, tartaric, or formic acid at low concentrations (<0.1 mol m −3 ) produced a drop in residual o ‐phosphate solubility at pH 5.5 and 7.0. In the case of citric acid, o ‐phosphate solubility gradually returned to its value in the absence of organic ligand as the ligand concentration was increased to 0.6 mol m −3 , whereas no such increase occurred in the case of tartaric or formic acid. This behavior was rationalized as the outcome principally of two competing reactions: (i) the reaction of adsorbed, polymeric hydroxy‐Al with organic ligand to form an exchangeable Al species that combined with o ‐phosphate to reduce its solubility, and (ii) the complexation of adsorbed Al to form a soluble Al‐organic complex that did not subsequently combine with o ‐phosphate. The latter reaction was important only for citric acid. The former reaction, favored by a large stability constant for Al‐organic acid adducts, produced o ‐phosphate solubility decreases in the order citrate > tartrate > formate.}, number={1}, journal={Soil Science Society of America Journal}, author={Traina, S.J. and Sposito, G. and Hesterberg, D. and Kafkafi, U.}, year={1986}, pages={45–52} }