@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} }
 @misc{peel_balogun_bowers_miller_obeidy_polizzotto_tashnia_vinson_duckworth_2022, title={Towards Understanding Factors Affecting Arsenic, Chromium, and Vanadium Mobility in the Subsurface}, volume={14}, ISSN={["2073-4441"]}, DOI={10.3390/w14223687}, abstractNote={Arsenic (As), chromium (Cr), and vanadium (V) are naturally occurring, redox-active elements that can become human health hazards when they are released from aquifer substrates into groundwater that may be used as domestic or irrigation source. As such, there is a need to develop incisive conceptual and quantitative models of the geochemistry and transport of potentially hazardous elements to assess risk and facilitate interventions. However, understanding the complexity and heterogeneous subsurface environment requires knowledge of solid-phase minerals, hydrologic movement, aerobic and anaerobic environments, microbial interactions, and complicated chemical kinetics. Here, we examine the relevant geochemical and hydrological information about the release and transport of potentially hazardous geogenic contaminants, specifically As, Cr, and V, as well as the potential challenges in developing a robust understanding of their behavior in the subsurface. We explore the development of geochemical models, illustrate how they can be utilized, and describe the gaps in knowledge that exist in translating subsurface conditions into numerical models, as well as provide an outlook on future research needs and developments.}, number={22}, journal={WATER}, author={Peel, Hannah R. and Balogun, Fatai O. and Bowers, Christopher A. and Miller, Cass T. and Obeidy, Chelsea S. and Polizzotto, Matthew L. and Tashnia, Sadeya U. and Vinson, David S. and Duckworth, Owen W.}, year={2022}, month={Nov} }
 @article{gillispie_matteson_duckworth_neumann_phen_polizzotto_2019, title={Chemical variability of sediment and groundwater in a Pleistocene aquifer of Cambodia: Implications for arsenic pollution potential}, volume={245}, ISSN={["1872-9533"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85057339109&partnerID=MN8TOARS}, DOI={10.1016/j.gca.2018.11.008}, abstractNote={Low-arsenic (As) groundwater from Pleistocene aquifers is vulnerable to future geogenic and allogenic arsenic pollution in South and Southeast Asia, threatening the millions who use it as a “safe source” of drinking and irrigation water. The abundance and chemical reactivity of iron and manganese oxides within these aquifer sediments control the occurrence and mobility of arsenic. In the present study, sediment samples varying in As, Fe, and Mn content were obtained from a Pleistocene aquifer in the Kandal Province of Cambodia. Laboratory and spectroscopic characterization of the sediment combined with groundwater analyses revealed that the availability and abundance of sedimentary As varied across a Pleistocene aquifer from the pore to field scales. Concentrations of sediment As (0.47–7 μg/g) correlated more strongly with Fe (R2 > 0.66) than with Mn (R2 > 0.35) concentrations in sediment well cuttings and tended to peak between 10 and 15 m. Chemical extractions and X-ray adsorption spectroscopy indicated the majority of As was strongly adsorbed to aquifer sediments or coprecipitated in oxides in the form of As(V) but that As(III) could be found in sediment microenvironments across the aquifer. Groundwater chemistry and Mn mineralogy indicated that the Pleistocene aquifer was suboxic, with average dissolved oxygen of 1.9 mg/L (±0.9 mg/L), redox potential of 0.155 V (±0.097 V), and abundant Mn(III/IV) oxide minerals. According to our results, allogenic As transport and geogenic As release will likely be dictated by localized geochemical processes that vary over a range of scales. Collectively, the specific Fe and Mn mineralogy and content within aquifers will ultimately govern As pollution potential, so understanding their multi-scale distributions and variability is essential for better predicting future risks to well-water quality in currently low-As aquifers.}, journal={GEOCHIMICA ET COSMOCHIMICA ACTA}, author={Gillispie, Elizabeth C. and Matteson, Audrey R. and Duckworth, Owen W. and Neumann, Rebecca B. and Phen, Nuon and Polizzotto, Matthew L.}, year={2019}, month={Jan}, pages={441–458} }
 @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} }
 @misc{ou_gannon_arellano_polizzotto_2018, title={A Global Meta-Analysis to Predict Atrazine Sorption from Soil Properties}, volume={47}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2017.11.0429}, abstractNote={Atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine) is one of the most widely used herbicides worldwide, and groundwater contamination is of concern, especially in heavily used regions and in edaphic conditions prone to leaching. Soil sorption plays an essential role in atrazine environmental fate, yet consistent atrazine risk prediction remains limited. A quantitative meta‐analysis was conducted to characterize the effect of soil properties on atrazine sorption, using 378 previous observations in 48 publications from 1985 to 2015 globally, which included data on soil properties and sorption parameters. A supplemental regional study was conducted to test the derived meta‐analysis models. The meta‐analysis indicated that percentage organic C (OC) was the most important parameter for estimating atrazine sorption, followed by percentage silt, soil pH, and percentage clay. Meta‐analysis and supplemental study models were developed for Freundlich sorption coefficients (Kf) and sorption distribution coefficients (Kd) as a function of OC. The global meta‐analysis models generated positive linear trends for OC with Kf and Kd (R2 = 0.197 and 0.205, respectively). Organic C was highly correlated with Kf and Kd in supplemental experimental study models (R2 = 0.93 and 0.92, respectively), indicating accurate prediction of sorption within the evaluated region. Continental models were investigated, which improved the goodness of fit. Models developed via meta‐analysis may be used to predict atrazine sorption over wide ranges of data, whereas more accurate and refined prediction can be achieved by specific regional models through experimental studies. However, such models could be improved if standardized agroclimatic conditions, soil classification, and other key variables were more widely reported.}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Ou, Ling and Gannon, Travis W. and Arellano, Consuelo and Polizzotto, Matthew L.}, year={2018}, pages={1389–1399} }
 @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{sun_polizzotto_guan_wu_shen_ran_wang_yu_2017, title={Exploring the interactions and binding sites between Cd and functional groups in soil using two-dimensional correlation spectroscopy and synchrotron radiation based spectromicroscopies}, volume={326}, ISSN={["1873-3336"]}, DOI={10.1016/j.jhazmat.2016.12.019}, abstractNote={Understanding how heavy metals bind and interact in soils is essential for predicting their distributions, reactions and fates in the environment. Here we propose a novel strategy, i.e., combining two-dimensional correlation spectroscopy (2D COS) and synchrotron radiation based spectromicroscopies, for identifying heavy metal binding to functional groups in soils. The results showed that although long-term (23 yrs) organic fertilization treatment caused the accumulation of Cd (over 3 times) in soils when compared to no fertilization and chemical fertilization treatments, it significantly (p < 0.05) reduced the Cd concentration in wheat grain. The 2D COS analyses demonstrated that soil functional groups controlling Cd binding were modified by fertilization treatments, providing implications for the reduced bioavailability of heavy metals in organic fertilized soils. Furthermore, correlative micro X-ray fluorescence spectromicroscopy, electron probe micro-analyzer mapping, and synchrotron-radiation-based FTIR spectromicroscopy analysis showed that Cd, minerals, and organic functional groups were heterogeneously distributed at the micro-scale in soil colloids. Only minerals, rather than organic groups, had a similar distribution pattern with Cd. Together, this strategy has a potential to explore the interactions and binding sites among heavy metals, minerals and organic components in soil.}, journal={JOURNAL OF HAZARDOUS MATERIALS}, author={Sun, Fusheng and Polizzotto, Matthew L. and Guan, Dongxing and Wu, Jun and Shen, Qirong and Ran, Wei and Wang, Boren and Yu, Guanghui}, year={2017}, month={Mar}, pages={18–25} }
 @article{ou_gannon_polizzotto_2017, title={Impact of soil organic carbon on monosodium methyl arsenate (MSMA) sorption and species transformation}, volume={186}, ISSN={["1879-1298"]}, DOI={10.1016/j.chemosphere.2017.07.147}, abstractNote={Monosodium methyl arsenate (MSMA), a common arsenical herbicide, is a major contributor of anthropogenic arsenic (As) to the environment. Uncertainty about controls on MSMA fate and the rates and products of MSMA species transformation limits effective MSMA regulation and management. The main objectives of this research were to quantify the kinetics and mechanistic drivers of MSMA species transformation and removal from solution by soil. Laboratory MSMA incubation studies with two soils and varying soil organic carbon (SOC) levels were conducted. Arsenic removal from solution was more extensive and faster in sandy clay loam incubations than sand incubations, but for both systems, As removal was biphasic, with initially fast removal governed by sorption, followed by slower As removal limited by species transformation. Dimethylarsinic acid was the dominant product of species transformation at first, but inorganic As(V) was the ultimate transformation product by experiment ends. SOC decreased As removal and enhanced As species transformation, and SOC content had linear relationships with As removal rates (R2 = 0.59–0.95) for each soil and reaction phase. These results reveal the importance of edaphic conditions on inorganic As production and overall mobility of As following MSMA use, and such information should be considered in MSMA management and regulatory decisions.}, journal={CHEMOSPHERE}, author={Ou, Ling and Gannon, Travis W. and Polizzotto, Matthew L.}, year={2017}, month={Nov}, pages={243–250} }
 @article{yu_xiao_hu_polizzotto_zhao_mcgrath_li_ran_shen_2017, title={Mineral Availability as a Key Regulator of Soil Carbon Storage}, volume={51}, ISSN={["1520-5851"]}, DOI={10.1021/acs.est.7b00305}, abstractNote={Mineral binding is a major mechanism for soil carbon (C) stabilization, and mineral availability for C binding critically affects C storage. Yet, the mechanisms regulating mineral availability are poorly understood. Here, we showed that organic amendments in three long-term (23, 154, and 170 yrs, respectively) field experiments significantly increased mineral availability, particularly of short-range-ordered (SRO) phases. Two microcosm studies demonstrated that the presence of roots significantly increased mineral availability and promoted the formation of SRO phases. Mineral transformation experiments and isotopic labeling experiments provided direct evidence that citric acid, a major component of root exudates, promoted the formation of SRO minerals, and that SRO minerals acted as "nuclei" for C retention. Together, these findings indicate that soil organic amendments initialize a positive feedback loop by increasing mineral availability and promoting the formation of SRO minerals for further C binding, thereby possibly serving as a management tool for enhancing carbon storage in soils.}, number={9}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Yu, Guanghui and Xiao, Jian and Hu, Shuijin and Polizzotto, Matthew L. and Zhao, Fangjie and McGrath, Steve P. and Li, Huan and Ran, Wei and Shen, Qirong}, year={2017}, month={May}, pages={4960–4969} }
 @article{duckworth_rivera_gardner_andrews_santelli_polizzotto_2017, title={Morphology, structure, and metal binding mechanisms of biogenic manganese oxides in a superfund site treatment system}, volume={19}, ISSN={["2050-7895"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85010739340&partnerID=MN8TOARS}, DOI={10.1039/c6em00525j}, abstractNote={Manganese oxides, which may be biogenically produced in both pristine and contaminated environments, have a large affinity for many trace metals.}, number={1}, journal={ENVIRONMENTAL SCIENCE-PROCESSES & IMPACTS}, author={Duckworth, O. W. and Rivera, N. A. and Gardner, T. G. and Andrews, M. Y. and Santelli, C. M. and Polizzotto, M. L.}, year={2017}, month={Jan}, pages={50–58} }
 @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{sowers_harrington_polizzotto_duckworth_2017, title={Sorption of arsenic to biogenic iron (oxyhydr)oxides produced in circumneutral environments}, volume={198}, ISSN={["1872-9533"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85007364750&partnerID=MN8TOARS}, DOI={10.1016/j.gca.2016.10.049}, abstractNote={Arsenic (As) is a widespread and problematic pollutant that can be derived from natural or anthropogenic sources. Iron (oxyhydr)oxides readily sorb As and thus play critical roles in As cycling in terrestrial environments; however, little is known about the affinity and mechanism of As sorption by biogenic iron (oxyhydr)oxides formed in circumneutral environments. To investigate this, we conducted sorption isotherm and kinetics experiments to compare As(V) and As(III) sorption to synthetic 2-line ferrihydrite and iron biominerals harvested from the hyporheic zone of an uncontaminated creek. Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify both As(V) and As(III), and X-ray absorption spectroscopy (XAS) was utilized to obtain As and Fe K-edge spectra for As(V) and As(III) sorbed to environmentally collected and laboratory produced Fe(III) minerals. All environmental Fe(III) biominerals were determined to be structurally similar to 2-line ferrihydrite. However, environmental Fe(III) biominerals have a surface area normalized affinity for As(V) and for As(III) that is greater than or equivalent to synthetic 2-line ferrihydrite. Whereas the extent of sorption was similar for As(III) on all minerals, As(V) sorption to environmental Fe(III) biominerals was approximately three times higher than what was observed for synthetic 2-line ferrihydrite. Structural modeling of EXAFS spectra revealed that the same surface complexation structure was formed by As(V) and by As(III) on environmental Fe(III) biominerals and ferrihydrite. These results suggest that, despite similarities in binding mechanisms, Fe(III) biominerals may be more reactive sorbents that synthetic surrogates often used to model environmental reactivity.}, journal={GEOCHIMICA ET COSMOCHIMICA ACTA}, author={Sowers, Tyler D. and Harrington, James M. and Polizzotto, Matthew L. and Duckworth, Owen W.}, year={2017}, month={Feb}, pages={194–207} }
 @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{gillispie_andujar_polizzotto_2016, title={Chemical controls on abiotic and biotic release of geogenic arsenic from Pleistocene aquifer sediments to groundwater}, volume={18}, ISSN={["2050-7895"]}, DOI={10.1039/c6em00359a}, abstractNote={Co-cycling of arsenic, manganese, iron, and dissolved organic carbon govern the extent and mode of geogenic arsenic mobilization into groundwater.}, number={8}, journal={ENVIRONMENTAL SCIENCE-PROCESSES & IMPACTS}, author={Gillispie, Elizabeth C. and Andujar, Erika and Polizzotto, Matthew L.}, year={2016}, month={Aug}, pages={1090–1103} }
 @article{matteson_graves_hall_kuy_polizzotto_2016, title={Fecal contamination and Microcystis in drinking-water sources of rural Cambodia using PCR and culture-based methods}, volume={6}, ISSN={["2043-9083"]}, DOI={10.2166/washdev.2016.136}, abstractNote={Rural communities within low-income countries frequently rely on a range of drinking-water sources, and each water source varies in its potential for biological contamination. The extent and source of biological contamination in primary drinking sources within Kien Svay, Kandal, Cambodia, were determined by fecal indicator bacteria (FIB) measurements, 16S rDNA genetic markers for human and bovine fecal Bacteroides, presence of the bloom-forming Microcystis species, and the microcystin toxin mcyD gene marker. Thirteen wells, 11 rain barrels, 10 surface-water sites, and five sediment samples were examined during the dry and wet seasons. Surface water was commonly contaminated with FIB, with up to 1.02 × 105Enterococcus sp., 6.13 × 104E. coli, and 2.91 × 104 total coliforms per 100 mL of water. Human and bovine Bacteroides were detected in 100 and 90% of the surface water samples, respectively. Concentrations of FIB in rain-barrels varied by site, however 91% contained human Bacteroides. Microcystis cells were found in 90% of surface water sites, with many also containing microcystin gene mcyD, representing the first report of microcystin-producing cyanobacteria in surface waters of Cambodia. The study results show that many potential drinking-water sources in Cambodia contain harmful bacterial and algal contaminants, and care should be taken when selecting and monitoring water options.}, number={3}, journal={JOURNAL OF WATER SANITATION AND HYGIENE FOR DEVELOPMENT}, author={Matteson, Audrey R. and Graves, Alexandria K. and Hall, Ann M. and Kuy, Dina and Polizzotto, Matthew L.}, year={2016}, month={Sep}, pages={353–361} }
 @article{li_hu_polizzotto_chang_shen_ran_yu_2016, title={Fungal biomineralization of montmorillonite and goethite to short-range-ordered minerals}, volume={191}, ISSN={["1872-9533"]}, DOI={10.1016/j.gca.2016.07.009}, abstractNote={Highly reactive nano-scale minerals, e.g., short-range-ordered minerals (SROs) and other nanoparticles, play an important role in soil carbon (C) retention. Yet, the mechanisms that govern biomineralization from bulk minerals to highly reactive nano-scale minerals remain largely unexplored, which critically hinders our efforts toward managing nano-scale minerals for soil C retention. Here we report the results from a study that explores structural changes during Aspergillus fumigatus Z5 transformation of montmorillonite and goethite to SROs. We examined the morphology and structure of nano-scale minerals, using high-resolution transmission electron microscopy, time-resolved solid-state 27Al and 29Si NMR, and Fe K-edge X-ray absorption fine structure spectroscopy combined with two dimensional correlation spectroscopy (2D COS) analysis. Our results showed that after a 48-h cultivation of montmorillonite and goethite with Z5, new biogenic intracellular and extracellular reactive nano-scale minerals with a size of 3–5 nm became abundant. Analysis of 2D COS further suggested that montmorillonite and goethite were the precursors of the dominant biogenic nano-scale minerals. Carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectra and their deconvolution results demonstrated that during fungus Z5 growth, carboxylic C (288.4–289.1 eV) was the dominant organic group, accounting for approximately 34% and 59% in the medium and aggregates, respectively. This result suggested that high percentage of the production of organic acids during the growth of Z5 was the driving factor for structural changes during biomineralization. This is, to the best of our knowledge, the first report of the structural characterization of nano-scale minerals by 2D COS, highlighting its potential to elucidate biomineralization pathways and thus identify the precursors of nano-scale minerals.}, journal={GEOCHIMICA ET COSMOCHIMICA ACTA}, author={Li, Huan and Hu, Shuijin and Polizzotto, Matthew L. and Chang, Xiaoli and Shen, Qirong and Ran, Wei and Yu, Guanghui}, year={2016}, month={Oct}, pages={17–31} }
 @article{vepraskas_polizzotto_faulkner_2016, title={Redox chemistry of hydric soils}, journal={Wetland Soils: Genesis, Hydrology, Landscapes, and Classification, 2nd edition}, author={Vepraskas, M. J. and Polizzotto, M. and Faulkner, S. P.}, year={2016}, pages={105–132} }
 @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{polizzotto_birgand_badruzzaman_ali_2015, title={Amending irrigation channels with jute-mesh structures to decrease arsenic loading to rice fields in Bangladesh}, volume={74}, ISSN={0925-8574}, url={http://dx.doi.org/10.1016/j.ecoleng.2014.10.030}, DOI={10.1016/j.ecoleng.2014.10.030}, abstractNote={Abstract Extensive use of arsenic-contaminated well water for irrigation of rice fields in Bangladesh has led to elevated arsenic concentrations in rice plants, decreased rice yields, and increased human exposure to arsenic. The goal of this study was to investigate whether arsenic removal from irrigation water could be improved within distribution channels by amending them with physical structures that both induce water treatment and maintain water-conveyance capacities. Chemical and hydraulic effects of amending channels with jute-mesh structures were characterized within 27 m-long experimental channels at a Bangladesh field site. Removal of total arsenic, iron and phosphorus from solution was enhanced within amended channels over unamended channels, with 7% of total As removed in amended channels vs. 3% in unamended channels. Increased elemental removal in amended channels was largely due to increases in residence time and particle-trapping efficiency, but removal via oxidative particle formation did not appear to be substantially enhanced. Results suggest that in-channel structures could be a useful tool for decreasing arsenic loading to rice fields, particularly where constrained channel spatial geometries limit the ability to overcome hydrogeochemical thresholds for enhanced arsenic removal. To improve the practical utility of structure-amended channels, future work could optimize structure designs and establish the season-long sustainability of enhanced arsenic-removal strategies.}, journal={Ecological Engineering}, publisher={Elsevier BV}, author={Polizzotto, Matthew L. and Birgand, François and Badruzzaman, A. Borhan M. and Ali, M. Ashraf}, year={2015}, month={Jan}, pages={101–106} }
 @article{mahoney_gannon_jeffries_polizzotto_2015, title={Arsenic Distribution and Speciation in a Managed Turfgrass System Following Monosodium Methylarsenate Application}, volume={55}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2015.03.0163}, abstractNote={ABSTRACT}, number={6}, journal={CROP SCIENCE}, author={Mahoney, Denis J. and Gannon, Travis W. and Jeffries, Matthew D. and Polizzotto, Matthew L.}, year={2015}, pages={2877–2885} }
 @article{mahoney_gannon_jeffries_matteson_polizzotto_2015, title={Management considerations to minimize environmental impacts of arsenic following monosodium methylarsenate (MSMA) applications to turfgrass}, volume={150}, ISSN={["1095-8630"]}, DOI={10.1016/j.jenvman.2014.12.027}, abstractNote={Monosodium methylarsenate (MSMA) is an organic arsenical herbicide currently utilized in turfgrass and cotton systems. In recent years, concerns over adverse impacts of arsenic (As) from MSMA applications have emerged; however, little research has been conducted in controlled field experiments using typical management practices. To address this knowledge gap, a field lysimeter experiment was conducted during 2012-2013 to determine the fate of As following MSMA applications to a bareground and an established turfgrass system. Arsenic concentrations in soil, porewater, and aboveground vegetation, were measured through one yr after treatment. Aboveground vegetation As concentration was increased compared to nontreated through 120 d after initial treatment (DAIT). In both systems, increased soil As concentrations were observed at 0-4 cm at 30 and 120 DAIT and 0-8 cm at 60 and 365 DAIT, suggesting that As was bound in shallow soil depths. Porewater As concentrations in MSMA-treated lysimeters from a 30-cm depth (22.0-83.8 μg L(-1)) were greater than those at 76-cm depth (0.4-5.1 μg L(-1)). These results were combined with previous research to devise management considerations in systems where MSMA is utilized. MSMA should not be applied if rainfall is forecasted within 7 DAIT and/or in areas with shallow water tables. Further, disposing of MSMA-treated turfgrass aboveground vegetation in a confined area - a common management practice for turfgrass clippings - may be of concern due to As release to surface water or groundwater as the vegetation decomposes. Finally, long-term MSMA use may cause soil As accumulation and thus downward migration of As over time; therefore, MSMA should be used in rotation with other herbicides.}, journal={JOURNAL OF ENVIRONMENTAL MANAGEMENT}, author={Mahoney, Denis J. and Gannon, Travis W. and Jeffries, Matthew D. and Matteson, Audrey R. and Polizzotto, Matthew L.}, year={2015}, month={Mar}, pages={444–450} }
 @article{matteson_gannon_jeffries_haines_lewis_polizzotto_2014, title={Arsenic Retention in Foliage and Soil after Monosodium Methyl Arsenate (MSMA) Application to Turfgrass}, volume={43}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2013.07.0268}, abstractNote={Monosodium methyl arsenate (MSMA) is a commonly used herbicide for weed control in turfgrass systems. There is concern that arsenic from applied MSMA could leach to groundwater or run off into surface water, thereby threatening human and ecosystem health. The USEPA has proposed a phase-out of the herbicide but is seeking additional research about the toxicity and environmental impacts of MSMA before establishing a final ruling. Little research has systematically investigated MSMA in field-based settings; instead, risks have been inferred from isolated field measurements or model-system studies. Accordingly, the overall goal of this study was to quantify the fate of arsenic after MSMA application to a managed turfgrass system. After MSMA application to turfgrass-covered and bareground lysimeters, the majority of arsenic was retained in turfgrass foliage and soils throughout year-long experiments, with 50 to 101% of the applied arsenic recovered in turfgrass systems and 55 to 66% recovered in bareground systems. Dissolved arsenic concentrations from 76.2-cm-depth pore water in the MSMA-treated soils were consistently <2 μg L, indistinguishable from background concentrations. As measured by adsorption isotherm experiments, MSMA retention by the sandy soil from our field site was markedly less than retention by a washed sand and a clay loam. Collectively, these results suggest that under aerobic conditions, minimal arsenic leaching to groundwater would occur after a typical application of MSMA to turfgrass. However, repeated MSMA application may pose environmental risks. Additional work is needed to examine arsenic cycling near the soil surface and to define arsenic speciation changes under different soil conditions.}, number={1}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Matteson, Audrey R. and Gannon, Travis W. and Jeffries, Matthew D. and Haines, Stephanie and Lewis, Dustin F. and Polizzotto, Matthew L.}, year={2014}, pages={379–388} }
 @article{matteson_mahoney_gannon_polizzotto_2014, title={Integrated Field Lysimetry and Porewater Sampling for Evaluation of Chemical Mobility in Soils and Established Vegetation}, ISSN={["1940-087X"]}, DOI={10.3791/51862}, abstractNote={Potentially toxic chemicals are routinely applied to land to meet growing demands on waste management and food production, but the fate of these chemicals is often not well understood. Here we demonstrate an integrated field lysimetry and porewater sampling method for evaluating the mobility of chemicals applied to soils and established vegetation. Lysimeters, open columns made of metal or plastic, are driven into bareground or vegetated soils. Porewater samplers, which are commercially available and use vacuum to collect percolating soil water, are installed at predetermined depths within the lysimeters. At prearranged times following chemical application to experimental plots, porewater is collected, and lysimeters, containing soil and vegetation, are exhumed. By analyzing chemical concentrations in the lysimeter soil, vegetation, and porewater, downward leaching rates, soil retention capacities, and plant uptake for the chemical of interest may be quantified. Because field lysimetry and porewater sampling are conducted under natural environmental conditions and with minimal soil disturbance, derived results project real-case scenarios and provide valuable information for chemical management. As chemicals are increasingly applied to land worldwide, the described techniques may be utilized to determine whether applied chemicals pose adverse effects to human health or the environment.}, number={89}, journal={JOVE-JOURNAL OF VISUALIZED EXPERIMENTS}, author={Matteson, Audrey R. and Mahoney, Denis J. and Gannon, Travis W. and Polizzotto, Matthew L.}, year={2014}, month={Jul} }
 @article{neumann_pracht_polizzotto_badruzzaman_ali_2014, title={Sealing Rice Field Boundaries in Bangladesh: A Pilot Study Demonstrating Reductions in Water Use, Arsenic Loading to Field Soils, and Methane Emissions from Irrigation Water}, volume={48}, ISSN={["1520-5851"]}, DOI={10.1021/es500338u}, abstractNote={Irrigation of rice fields in Bangladesh with arsenic-contaminated and methane-rich groundwater loads arsenic into field soils and releases methane into the atmosphere. We tested the water-savings potential of sealing field bunds (raised boundaries around field edges) as a way to mitigate these negative outcomes. We found that, on average, bund sealing reduced seasonal water use by 52 ± 17% and decreased arsenic loading to field soils by 15 ± 4%; greater savings in both water use and arsenic loading were achieved in fields with larger perimeter-to-area ratios (i.e., smaller fields). Our study is the first to quantify emission of methane from irrigation water in Bangladesh, a currently unaccounted-for methane source. Irrigation water applied to unsealed fields at our site emits 18 to 31 g of methane per square-meter of field area per season, potentially doubling the atmospheric input of methane from rice cultivation. Bund sealing reduced the emission of methane from irrigation water by 4 to 19 g/m(2). While the studied outcomes of bund sealing are positive and compelling, widespread implementation of the technique should consider other factors, such as effect on yields, financial costs, and impact on the hydrologic system. We provide an initial and preliminary assessment of these implementation factors.}, number={16}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Neumann, Rebecca B. and Pracht, Lara E. and Polizzotto, Matthew L. and Badruzzaman, A. Borhan M. and Ali, M. Ashraf}, year={2014}, month={Aug}, pages={9632–9640} }
 @article{lineberger_badruzzaman_ali_polizzotto_2013, title={Arsenic Removal from Flowing Irrigation Water in Bangladesh: Impacts of Channel Properties}, volume={42}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2013.05.0191}, abstractNote={Across Bangladesh, dry-season irrigation with arsenic-contaminated well water is loading arsenic onto rice paddies, leading to increased arsenic concentrations in plants, diminished crop yields, and increased human health risks. As irrigation water flows through conveyance channels between wells and rice fields, arsenic concentrations change over space and time, indicating that channels may provide a location for removing arsenic from solution. However, few studies have systematically evaluated the processes controlling arsenic concentrations in irrigation channels, limiting the ability to manipulate these systems and enhance arsenic removal from solution. The central goal of this study was to quantify how channel design affected removal of dissolved arsenic from flowing irrigation water. Field experiments were conducted in Bangladesh using a chemically constant source of arsenic-contaminated irrigation water and an array of constructed channels with varying geometries. The resulting hydraulic conditions affected the quantity of arsenic removed from solution within the channels by promoting known hydrogeochemical processes. Channels three times the width of control channels removed ∼3 times the mass of arsenic over 32 min of flowing conditions, whereas negligible arsenic removal was observed in tarp-lined channels, which prevented soil-water contact. Arsenic removal from solution was ∼7 times higher in a winding, 200-m-long channel than in the straight, 45-m-long control channels. Arsenic concentrations were governed by oxidative iron-arsenic coprecipitation within the water column, sorption to soils, and phosphate competition. Collectively, these results suggest that better design and management of irrigation channels may play a part in arsenic mitigation strategies for rice fields in Southern Asia.}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Lineberger, Ethan M. and Badruzzaman, A. Borhan M. and Ali, M. Ashraf and Polizzotto, Matthew L.}, year={2013}, pages={1733–1742} }
 @article{polizzotto_lineberger_matteson_neumann_badruzzaman_ali_2013, title={Arsenic transport in irrigation water across rice-field soils in Bangladesh}, volume={179}, ISSN={["0269-7491"]}, DOI={10.1016/j.envpol.2013.04.025}, abstractNote={Experiments were conducted to analyze processes impacting arsenic transport in irrigation water flowing over bare rice-field soils in Bangladesh. Dissolved concentrations of As, Fe, P, and Si varied over space and time, according to whether irrigation water was flowing or static. Initially, under flowing conditions, arsenic concentrations in irrigation water were below well-water levels and showed little spatial variability across fields. As flowing-water levels rose, arsenic concentrations were elevated at field inlets and decreased with distance across fields, but under subsequent static conditions, concentrations dropped and were less variable. Laboratory experiments revealed that over half of the initial well-water arsenic was removed from solution by oxidative interaction with other water-column components. Introduction of small quantities of soil further decreased arsenic concentrations in solution. At higher soil-solution ratios, however, soil contributed arsenic to solution via abiotic and biotic desorption. Collectively, these results suggest careful design is required for land-based arsenic-removal schemes.}, journal={ENVIRONMENTAL POLLUTION}, author={Polizzotto, Matthew L. and Lineberger, Ethan M. and Matteson, Audrey R. and Neumann, Rebecca B. and Badruzzaman, A. Borhan M. and Ali, M. Ashraf}, year={2013}, month={Aug}, pages={210–217} }
 @misc{graham_polizzotto_2013, title={Pit latrines and their impacts on groundwater quality: A systematic review}, volume={121}, number={5}, journal={Environmental Health Perspectives}, author={Graham, J. P. and Polizzotto, M. L.}, year={2013}, pages={521–530} }