@article{aneja_blunden_roelle_schlesinger_knighton_niyogi_gilliam_jennings_duke_2008, title={Workshop on Agricultural Air Quality: State of the science}, volume={42}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-41449102642&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2007.07.043}, abstractNote={The first Workshop on Agricultural Air Quality: State of the Science was held at the Bolger Center in Potomac, Maryland from 4 to 8 June 2006. This international conference assembled approximately 350 people representing 25 nations from 5 continents, with disciplines ranging from atmospheric chemistry to soil science. The workshop was designed as an open forum in which participants could openly exchange the most current knowledge and learn about numerous international perspectives regarding agricultural air quality. Participants represented many stakeholder groups concerned with the growing need to assess agricultural impacts on the atmosphere and to develop beneficial policies to improve air quality. The workshop focused on identifying methods to improve emissions inventories and best management practices for agriculture. Workshop participants also made recommendations for technological and methodological improvements in current emissions measurement and modeling practices. The workshop commenced with a session on agricultural emissions and was followed by international perspectives from the United States, Europe, Australia, India, and South America. This paper summarizes the findings and issues of the workshop and articulates future research needs. These needs were identified in three general areas: (1) improvement of emissions measurement; (2) development of appropriate emission factors; and (3) implementation of best management practices (BMPs) to minimize negative environmental impacts. Improvements in the appropriate measurements will inform decisions regarding US farming practices. A need was demonstrated for a national/international network to monitor atmospheric emissions from agriculture and their subsequent depositions to surrounding areas. Information collected through such a program may be used to assess model performance and could be critical for evaluating any future regulatory policies or BMPs. The workshop concluded that efforts to maximize benefits and reduce detrimental effects of agricultural production need to transcend disciplinary, geographic, and political boundaries. Also, such efforts should involve natural and social scientists, economists, engineers, business leaders, and decision makers. The workshop came to the conclusion that through these collaborative efforts improvements in air quality from agricultural practices will begin to take effect.}, number={14}, journal={ATMOSPHERIC ENVIRONMENT}, author={Aneja, Viney P. and Blunden, Jessica and Roelle, Paul A. and Schlesinger, William H. and Knighton, Raymond and Niyogi, Dev and Gilliam, Wendell and Jennings, Greg and Duke, Clifford S.}, year={2008}, month={Apr}, pages={3195–3208} }
 @article{aneja_niyogi_roelle_2006, title={An integrated perspective on assessing agricultural air quality}, volume={6}, ISBN={1466-6650}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33746227332&partnerID=MN8TOARS}, DOI={10.1504/ijgenvi.2006.010146}, abstractNote={The biogeochemical cycling of trace gases (e.g. nitrogen, sulphur, etc.), and contaminants on local, regional, and global scales is a complex system of emissions, transformations, transport, and deposition. To date, limited, if any, attempt has been made on quantifying and identifying direct emissions of gaseous sulphur compounds from agricultural operations. This represents a major regulatory need for sound and prudent environmental practice. In this paper, we summarise an integrated assessment framework for studying the agricultural air quality issues by discussing the various components of the research, education and outreach involved.}, number={2-3}, journal={International Journal of Global Environmental Issues}, author={Aneja, Viney and Niyogi, D. and Roelle, P.A.}, year={2006}, pages={137–148} }
 @article{roelle_aneja_2005, title={Modeling of ammonia emissions from soils}, volume={22}, ISSN={["1557-9018"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-11444269556&partnerID=MN8TOARS}, DOI={10.1089/ees.2005.22.58}, abstractNote={Using a dynamic flow-through chamber system in conjunction with a Thermo Environmental 17C Chemiluminescence ammonia (NH3) analyzer, emissions from slurry-amended, that is, effluent from the lagoon (∼33 kg N ha-1) and nonamended soils were calculated at a swine farm in eastern North Carolina. The average NH3-N flux values during the period when the soils were not amended with any slurry were ∼54 ng N m-2 s-1, while the average NH3-N flux values measured immediately following the application of slurry to the soil were 1723.9 ng N m-2 s-1. An empirical model relating soil temperature to NH3 flux for nonamended soils explained over 70% of the variability in NH3 emissions; however, a similar empirical model relating soil temperature to NH3 flux for slurry-amended soils was able to explain only 39% of the variability in NH3 emissions. A mass transport model, based on physical and chemical processes to estimate NH3 emissions from recently amended soils is also presented and compared and contrasted to the empiri...}, number={1}, journal={ENVIRONMENTAL ENGINEERING SCIENCE}, author={Roelle, PA and Aneja, VP}, year={2005}, pages={58–72} }
 @article{aneja_nelson_roelle_walker_battye_2003, title={Agricultural ammonia emissions and ammonium concentrations associated with aerosols and precipitation in the southeast United States}, volume={108}, ISSN={["2169-8996"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-1642562702&partnerID=MN8TOARS}, DOI={10.1029/2002jd002271}, abstractNote={Temporal and spatial variations in ammonia (NH3) emissions and ammonium (NH4+) concentrations associated with aerosols and volume‐weighted NH4+ concentration in precipitation are investigated over the period 1990–1998 in the southeast United States (Alabama, Florida, Georgia, Kentucky, North Carolina, South Carolina, Mississippi, and Tennessee). These variations were analyzed using an NH3 emissions inventory developed for the southeast United States and ambient NH4+ data from the various Clean Air Status and Trends Network (CASTNet) and the National Atmospheric Deposition Program/National Trends Network (NADP/NTN). Results show that natural log‐transformed annual NH4+ concentration associated with aerosols increases with natural log‐transformed annual NH3 emission density within the same county (R2 = 0.86, p < 0.0001, N = 12). Natural log‐transformed annual volume‐weighted average NH4+ concentration in precipitation shows only a very weak positive correlation with natural log‐transformed annual NH3 emission densities within the corresponding county (R2 = 0.12, p = 0.04, N = 29). Analysis of NH4+ concentration associated with aerosols at CASTNet sites revealed that temperature, precipitation amount, and relative humidity are the most statistically significant (p < 0.05) parameters in predicting the weekly concentrations of NH4+ during the period 1990–1998. Wind speed and wind direction were also statistically significant (p < 0.05) at several CASTNet sites, but the results were less consistent. Investigation into wet NH4+ concentration in precipitation consistently yielded temperature as a statistically significant (p < 0.05) parameter at individual sites. Trends over the period 1990–1998 revealed a slight decrease in NH4+ concentration at CASTNet site SPD, Claiborne County, Tennessee (2.14–1.88 μg m−3), while positive trends in NH4+ concentration in precipitation were evident at NADP sites NC35, Sampson County, North Carolina (0.2–0.48 mg L−1) and KY35, Rowan County, Kentucky (0.2–0.35 mg L−1) over the period 1990–1998.}, number={D4}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Aneja, VP and Nelson, DR and Roelle, PA and Walker, JT and Battye, W}, year={2003}, month={Feb} }
 @article{battye_aneja_roelle_2003, title={Evaluation and improvement of ammonia emissions inventories}, volume={37}, ISSN={["1352-2310"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0042167618&partnerID=MN8TOARS}, DOI={10.1016/S1352-2310(03)00343-1}, abstractNote={Two case studies are performed to improve ammonia emissions inputs used to model fine particulate matter (PM2.5 is the portion of particulate matter smaller than 2.5 μm aerodynamic diameter) formation of ammonium sulfate and ammonium nitrate. Ammonia emissions are analyzed in detail for North Carolina and the San Joaquin Valley (SJV) of California, with a focus on the Charlotte, NC, and Fresno, California metropolitan areas. A new gridded ammonia emissions inventories suitable for atmospheric modeling for the two case study cities was also developed. Agricultural sources accounted for the bulk of ammonia emissions in both case studies. Livestock waste contributed about 80% in North Carolina and 64% in the SJV, while fertilizer application contributed about 6–7% in both domains. Forests and non-agricultural vegetation contributed 5% in North Carolina and 12% in the SJV. Motor vehicles accounted for about 6% of ammonia emissions in North Carolina and 14% in the SJV. In the Charlotte and Fresno urban areas, the distribution of emissions is less heavily weighted toward agricultural sources and more heavily weighted toward highway vehicles (highway vehicles account for an estimated 64% of emissions in Charlotte and 51% of emissions in Fresno). The emissions estimates for agricultural sources (livestock and fertilizer application) decline to approximately 14% in the winter for both the Charlotte and Fresno urban areas. Emissions estimates for soils and vegetation also decline to approximately 0 during the winter for both the Fresno and Charlotte area. As a result, motor vehicles account for a larger fraction (approximately 73% and 70% for Charlotte and Fresno, respectively) of winter ammonia emissions, particularly in the Charlotte urban area.}, number={27}, journal={ATMOSPHERIC ENVIRONMENT}, author={Battye, W and Aneja, VP and Roelle, PA}, year={2003}, month={Sep}, pages={3873–3883} }
 @article{roelle_aneja_2002, title={Characterization of ammonia emissions from soils in the upper coastal plain, North Carolina}, volume={36}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036150359&partnerID=MN8TOARS}, DOI={10.1016/S1352-2310(01)00355-7}, abstractNote={A dynamic flow-through chamber system was used to measure fluxes of ammonia-nitrogen (NH3-N, where NH3-N=(14/17)NH3) from soil surfaces. The research site was located in eastern North Carolina (35.9°N latitude; 77.7°W longitude) and measurements were conducted during spring and winter 2000, in order to assess the NH3 source strength of intensively managed agricultural soils and the physiochemical properties which control these emissions. Soil temperature (Tsoil), soil pH, soil moisture, total Kjeldahl nitrogen (TKN=organic N+NH3-N+NH4+-N) were monitored throughout both research periods. Soil temperature was found to explain the largest variability in soil NH3 emissions (Log10 NH3-N Flux=0.054Tsoil+0.66; R2=0.71), suggesting that an approach similar in design to the biogenic emissions inventory system land use and temperature model for NO emissions, might be effective for modeling biogenic NH3 emissions. Soil nitrogen was also significant in predicting NH3 flux [NH3 Flux=55.5(NH3-N)−160, R2=0.86; NH3 Flux=0.6(TKN)−410, R2=0.27], but only after the two days with the heaviest rainfall were removed from the regression, emphasizing the role of soil moisture in controlling the transfer of gases across the soil/air interface. Soil pH remained relatively constant throughout both research periods and therefore did not serve as a useful predictor of NH3 flux. A rain event, followed by a drying period produced a characteristic pulse in ammonia emissions. This pulsing phenomenon has been observed for other trace gases by various researchers. This research location was the site of a commercial hog operation, which allowed for the comparison of soil and lagoon emissions (lagoon emissions were based on an algorithm developed by Aneja et al. (J. Geophys. Res. 105 (2000) 11,535). An analysis of the source strengths confirmed that lagoon emissions are a larger flux source (average lagoon flux ∼18,137 ng N m−2 s−1; average soil flux ∼54 ng N m−2 s−1); however soil surfaces make up a larger fraction of a commercial hog operation than the lagoon surfaces, and as a result they cannot be neglected when developing and apportioning NH3 emissions. A yearly average of ammonia emissions at this site revealed that soil emissions represent approximately 28% of the lagoon emissions.}, number={6}, journal={ATMOSPHERIC ENVIRONMENT}, author={Roelle, PA and Aneja, VP}, year={2002}, month={Feb}, pages={1087–1097} }
 @article{roelle_aneja_mathur_vukovich_peirce_2002, title={Modeling nitric oxide emissions from biosolid amended soils}, volume={36}, ISSN={["1352-2310"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036888563&partnerID=MN8TOARS}, DOI={10.1016/S1352-2310(02)00655-6}, abstractNote={Utilizing a state-of-the-art mobile laboratory in conjunction with a dynamic flow-through chamber system, nitric oxide concentrations [NO] were measured and NO fluxes were calculated during the summer, winter and spring of 1999/2000. The field site where these measurements were conducted was an agricultural soil amended with biosolids from a municipal wastewater treatment facility. These NO flux values were then used to assess the impact of including biosolid amended soils as a land-use class in an air quality model. The average NO flux from this biosolid amended soil was found to be exponentially dependent on soil temperature [NO Flux (ngNm−2s−1)=1.07exp(0.14Tsoil); R2=0.81—NO Flux=71.3ngNm−2s−1 at 30°C]. Comparing this relationship to results of the widely applied biogenic emissions inventory system (BEIS2) model revealed that for this field site, if the BEIS2 model was used, the NO emissions would have been underestimated by a factor of 26. Using this newly developed NO flux algorithm, combined with North Carolina Division of Water Quality statistics on how many biosolid amended acres are permitted per county, county-based NO inventories from these biosolid amended soils were calculated. Results from this study indicate that county-level biogenic NO emissions can increase by as much as 18% when biosolid amended soils are included as a land-use class. The multiscale air quality simulation platform (MAQSIP) was then used to determine differences in ozone (O3) and odd-reactive nitrogen compounds (NOy) between models run with and without the biosolid amended acreages included in the inventory. Results showed that during the daytime, when atmospheric mixing heights are typically at their greatest, any increase in O3 or NOy concentrations predicted by the model were small (<3%). In some locations during late evening/early morning hours, ozone was found to be consumed by as much as 11%.}, number={36-37}, journal={ATMOSPHERIC ENVIRONMENT}, author={Roelle, PA and Aneja, VP and Mathur, R and Vukovich, J and Peirce, J}, year={2002}, month={Dec}, pages={5687–5696} }
 @article{roelle_aneja_2002, title={Nitric oxide emissions from soils amended with municipal waste biosolids}, volume={36}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036136766&partnerID=MN8TOARS}, DOI={10.1016/S1352-2310(01)00415-0}, abstractNote={Land spreading nitrogen-rich municipal waste biosolids (NO3 -No256 mg N kg � 1 dry weight, NH3-NB23,080 mg Nk g � 1 dry weight, Total Kjeldahl NB41,700 mg N kg � 1 dry weight) to human food and non-food chain land is a practice followed throughout the US. This practice may lead to the recovery and utilization of the nitrogen by vegetation, but it may also lead to emissions of biogenic nitric oxide (NO), which may enhance ozone pollution in the lower levels of the troposphere. Recent global estimates of biogenic NO emissions from soils are cited in the literature, which are based on field measurements of NO emissions from various agricultural and non-agricultural fields. However, biogenic emissions of NO from soils amended with biosolids are lacking. Utilizing a state-of-the-art mobile laboratory and a dynamic flow-through chamber system, in-situ concentrations of nitric oxide (NO) were measured during the spring/summer of 1999 and winter/spring of 2000 from an agricultural soil which is routinely amended with municipal waste biosolids. The average NO flux for the late spring/summer time period (10 June 1999–5 August 1999) was 69.4734.9 ng N m � 2 s � 1 . Biosolids were applied during September 1999 and the field site was sampled again during winter/spring 2000 (28 February 2000–9 March 2000), during which the average flux was 3.671.7 ng N m � 2 s � 1 . The same field site was sampled again in late spring (2–9 June 2000) and the average flux was 64.8741.0 ng N m � 2 s � 1 .A n observationally based model, developed as part of this study, found that summer accounted for 60% of the yearly emission while fall, winter and spring accounted for 20%, 4% and 16% respectively. Field experiments were conducted which indicated that the application of biosolids increases the emissions of NO and that techniques to estimate biogenic NO emissions would, on a yearly average, underestimate the NO flux from this field by a factor of 26. Soil temperature and % water filled pore space (%WFPS) were observed to be significant variables for predicting NO emissions, however %WFPS was found to be most significant during high soil temperature conditions. In the range of pH values found at this site (5.870.3), pH was not observed to be a significant parameter in predicting NO emissions. r 2002 Elsevier Science Ltd. All rights reserved.}, number={1}, journal={ATMOSPHERIC ENVIRONMENT}, author={Roelle, PA and Aneja, VP}, year={2002}, month={Jan}, pages={137–147} }
 @article{tabachow_roelle_peirce_aneja_2002, title={Soil nitric oxide emissions: Lab and field measurements and comparison}, volume={19}, ISSN={["1092-8758"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0242488928&partnerID=MN8TOARS}, DOI={10.1089/109287502760271526}, abstractNote={Equipment and procedures are developed and implemented to measure nitric oxide (NO) emissions from unamended and municipal wastewater treatment plant biosolids-amended soil in controlled laboratory...}, number={4}, journal={ENVIRONMENTAL ENGINEERING SCIENCE}, author={Tabachow, RM and Roelle, PA and Peirce, JJ and Aneja, VP}, year={2002}, pages={205–214} }
 @article{aneja_roelle_murray_southerland_erisman_fowler_asman_patni_2001, title={Atmospheric nitrogen compounds II: emissions, transport, transformation, deposition and assessment}, volume={35}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034744409&partnerID=MN8TOARS}, DOI={10.1016/S1352-2310(00)00543-4}, abstractNote={The Atmospheric Nitrogen Compounds II: Emissions, Transport, Transformation, Deposition and Assessment workshop was held in Chapel Hill, NC from 7 to 9 June 1999. This international conference, which served as a follow-up to the workshop held in March 1997, was sponsored by: North Carolina Department of Environment and Natural Resources; North Carolina Department of Health and Human Services, North Carolina Office of the State Health Director; Mid-Atlantic Regional Air Management Association; North Carolina Water Resources Research Institute; Air and Waste Management Association, RTP Chapter; the US Environmental Protection Agency and the North Carolina State University (College of Physical and Mathematical Sciences, and North Carolina Agricultural Research Service). The workshop was structured as an open forum at which scientists, policy makers, industry representatives and others could freely share current knowledge and ideas, and included international perspectives. The workshop commenced with international perspectives from the United States, Canada, United Kingdom, the Netherlands, and Denmark. This article summarizes the findings of the workshop and articulates future research needs and ways to address nitrogen/ammonia from intensively managed animal agriculture. The need for developing sustainable solutions for managing the animal waste problem is vital for shaping the future of North Carolina. As part of that process, all aspects of environmental issues (air, water, soil) must be addressed as part of a comprehensive and long-term strategy. There is an urgent need for North Carolina policy makers to create a new, independent organization that will build consensus and mobilize resources to find technologically and economically feasible solutions to this aspect of the animal waste problem.}, number={11}, journal={ATMOSPHERIC ENVIRONMENT}, author={Aneja, VP and Roelle, PA and Murray, GC and Southerland, J and Erisman, JW and Fowler, D and Asman, WAH and Patni, N}, year={2001}, pages={1903–1911} }
 @article{roelle_aneja_gay_geron_pierce_2001, title={Biogenic nitric oxide emissions from cropland soils}, volume={35}, ISSN={["1352-2310"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0035238856&partnerID=MN8TOARS}, DOI={10.1016/S1352-2310(00)00279-X}, abstractNote={Emissions of nitric oxide (NO) were determined during late spring and summer 1995 and the spring of 1996 from four agricultural soils on which four different crops were grown. These agricultural soils were located at four different sites throughout North Carolina. Emission rates were calculated using a dynamic flow-through chamber system coupled to a mobile laboratory for in-situ analysis. Average NO fluxes during late spring 1995 were: 50.9±47.7 ng N m−2 s−1 from soil planted with corn in the lower coastal plain. Average NO fluxes during summer 1995 were: 6.4±4.6 and 20.2±19.0 ng N m−2 s−1, respectively, from soils planted with corn and soybean in the coastal region; 4.2±1.7 ng N m−2 s−1 from soils planted with tobacco in the piedmont region; and 8.5±4.9 ng N m−2 s−1 from soils planted with corn in the upper piedmont region. Average NO fluxes for spring 1996 were: 66.7±60.7 ng N m−2 s−1 from soils planted with wheat in the lower coastal plain; 9.5±2.9 ng N m−2 s−1 from soils planted with wheat in the coastal plain; 2.7±3.4 ng N m−2 s−1 from soils planted with wheat in the piedmont region; and 56.1±53.7 ng N m−2 s−1 from soils planted with corn in the upper piedmont region. An apparent increase in NO flux with soil temperature was present at all of the locations. The composite data from all the research sites revealed a general positive trend of increasing NO flux with soil water content. In general, increases in total extractable nitrogen (TEN) appeared to be related to increased NO emissions within each site, however a consistent trend was not evident across all sites.}, number={1}, journal={ATMOSPHERIC ENVIRONMENT}, author={Roelle, PA and Aneja, VP and Gay, B and Geron, C and Pierce, T}, year={2001}, pages={115–124} }
 @article{aneja_roelle_li_2001, title={Effect of environmental variables on NO emissions from agricultural soils}, volume={41}, number={3}, journal={Phyton}, author={Aneja, V. P. and Roelle, P. A. and Li, Y.}, year={2001}, pages={29–40} }
 @article{aneja_agarwal_roelle_phillips_tong_watkins_yablonsky_2001, title={Measurements and analysis of criteria pollutants in New Delhi, India}, volume={27}, ISSN={["0160-4120"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034923291&partnerID=MN8TOARS}, DOI={10.1016/S0160-4120(01)00051-4}, abstractNote={Ambient concentrations of carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), and total suspended particulates (TSP) were measured from January 1997 to November 1998 in the center of downtown [the Income Tax Office (ITO) located on B.S.G. Marg] New Delhi, India. The data consist of 24-h averages of SO2, NOx, and TSP as well as 8 and 24-h averages of CO. The measurements were made in an effort to characterize air pollution in the urban environment of New Delhi and assist in the development of an air quality index. The yearly average CO, NOx, SO2, and TSP concentrations for 1997 and 1998 were found to be 4810±2287 and 5772±2116 μg/m3, 83±35 and 64±22 μg/m3, 20±8 and 23±7 μg/m3, and 409±110 and 365±100 μg/m3, respectively. In general, the maximum CO, SO2, NOx, and TSP values occurred during the winter with minimum values occurring during the summer, which can be attributed to a combination of meteorological conditions and photochemical activity in the region. The ratio of CO/NOx (∼50) indicates that mobile sources are the predominant contributors for these two compounds in the urban air pollution problem in New Delhi. The ratio of SO2/NOx (∼0.6) indicates that point sources are contributing to SO2 pollution in the city. The averaged background CO concentrations in New Delhi were also calculated (∼1939 μg/m3) which exceed those for Eastern USA (∼500 μg/m3). Further, all measured concentrations exceeded the US National Ambient Air Quality Standards (NAAQS) except for SO2. TSP was identified as exceeding the standard on the most frequent basis.}, number={1}, journal={ENVIRONMENT INTERNATIONAL}, author={Aneja, VP and Agarwal, A and Roelle, PA and Phillips, SB and Tong, QS and Watkins, N and Yablonsky, R}, year={2001}, month={Jul}, pages={35–42} }
 @article{roelle_aneja_j o'connor_robarge_kim_levine_1999, title={Measurement of nitrogen oxide emissions from an agricultural soil with a dynamic chamber system}, volume={104}, ISSN={["2169-8996"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0033585537&partnerID=MN8TOARS}, DOI={10.1029/98JD01202}, abstractNote={Biogenic soil emissions of nitric oxide (NO) were measured from an intensively managed agricultural row crop (corn, Zea mays) during a 4 week period (May 15 through June 9, 1995). The site was located in Washington County, near the town of Plymouth, which is in the Lower Coastal Plain of North Carolina. Soil NO flux was determined using a dynamic flowthrough chamber technique. The measurement period was characterized by two distinguishing features: an application of nitrogen (N) fertilizer at the midpoint of the experiment and a nontypical rainfall pattern. Average NO flux prior to the application of N fertilizer was 31.5 ± 10.1 ng N m−2 s−1, and more than doubled (77.7 ± 63.7 ng N m−2 s−1) after the application of a side‐dressing of N fertilizer. Average soil extractable nitrogen values did not change significantly following application of the side‐dressing of N fertilizer. We attribute this failure to detect a significant difference in soil extractable nitrogen following N fertilization to the method in which the fertilizer was applied, the subsequent rainfall pattern, and the technique of soil sampling. NO flux followed the same diurnal trend as soil temperature, with maximum NO emissions coinciding with maximum soil temperature, and minimum NO emissions coinciding with minimum soil temperature. NO flux was found to increase exponentially with soil temperature, but only after fertilization. Due to subsurface irrigation practices employed by the farmer, changes in soil water content were minimal, and no relation could be drawn between soil water content and NO flux. Simultaneous measurements of NOy, NO2, and NO emissions revealed that NO and NO2 emissions represent 86 and 8.7%, respectively, of NOy emissions leaving the soil. Simultaneous NO flux measurements made by a closed box flux technique, at the same site, revealed no statistically significant differences between the two different methodologies for measuring NO flux.}, number={D1}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Roelle, P and Aneja, VP and J O'Connor and Robarge, W and Kim, DS and Levine, JS}, year={1999}, month={Jan}, pages={1609–1619} }
 @article{li_aneja_arya_rickman_brittig_roelle_kim_1999, title={Nitric oxide emission from intensively managed agricultural soil in North Carolina}, volume={104}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-17044382146&partnerID=MN8TOARS}, DOI={10.1029/1999JD900336}, abstractNote={Emissions of nitric oxide (NO) were determined from an intensively managed agricultural soil near Plymouth, in the coastal plain of North Carolina, using the dynamic chamber technique. The measurements were made over a soybean field from July 15 to August 15, 1996, as part of the project Natural Emissions of Oxidant Precursors: Validation of Techniques and Assessment (NOVA). A N‐containing fertilizer was applied at the middle of the experiment in order to investigate the effect of N‐fertilizers on NO emissions and to test the response of instruments. Soil water content was high during the experimental period, with water‐filled pore space ranging from 49% to 67%. NO emission during this period ranged between 0.28 and 18.45 ng N m−2 s−1, with an overall average of 5.01±3.03 ng N m−2 s−1. A normal diurnal pattern with low values at nighttime and high values during the day was observed during the prefertilization period, but a reverse diurnal pattern (high at nighttime, low in daytime) of NO emission variation was found during the postfertilization, closed‐canopy period, implying that interaction among canopy development, application of fertilization, and soil parameters may affect the diurnal variation of NO emission from soils. The emissions of NO were related to soil temperature, water‐filled pore space, and extractable nitrogen. Application of fertilizer at the middle of the experiment was found to disrupt the normal relations between NO emission and soil temperature and water content seen during the prefertilization period but to enhance the positive relation between NO emission and extractable N. An intercomparison of the dynamic chamber technique with the eddy‐correlation technique in this experiment indicates that in spite of large differences in the magnitudes of soil NO emission and the NO flux at 5 m, the two fluxes show similar variations with time and are strongly correlated.}, number={D21}, journal={Journal of Geophysical Research Atmospheres}, author={Li, Y. and Aneja, Viney and Arya, S.P. and Rickman, J. and Brittig, J. and Roelle, P. and Kim, D.S.}, year={1999}, pages={26115–26123} }
 @article{aneja_roelle_robarge_1998, title={Characterization of biogenic nitric oxide source strength in the southeast United States}, volume={102}, ISSN={["0269-7491"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032446054&partnerID=MN8TOARS}, DOI={10.1016/S0269-7491(98)80035-3}, abstractNote={Emissions of nitric oxide (NO) were measured during the summer of 1995 from 4 crops, located at three different sites throughout North Carolina. These sites were chosen to represent major physiographic regions of the Southeast US, in an effort to compare fluxes from different agriculturally managed soils. Emission rates were determined using a dynamic flow-through chamber system. In order to understand the NO flux from the different soil and crop types, measurements were made on corn and soybean crops in the coastal region, tobacco in the Piedmont region, and corn in the upper Piedmont region of North Carolina. Average NO fluxes were 5.5 f 2.2 ng N me2 s-‘, 20.7 + 19.2 ng N me2 s-‘, 4.1 + 1.4 ng N m-2s-1, and 8.5 2 4.9 ng N me2 s-l respectively for corn and soybean in the coastal region, tobacco in the Piedmont region, and corn in the upper Piedmont region. We were only able to detect an exponential dependence of NO flux on soil temperature at two of the locations. Tbe composite data of all the research sites revealed a general trend of increasing NO flux with soil water content or increasing extractable nitrogen in the soil, however, the day to day variations within each site did not reveal the same trends. We feel that acquisition of a soil NO flux data set in this fashion, which consists of observations collected over different points in both space and time, makes attempts to model soil NO flux in terms of different soil parameters difficult.}, number={SUPPL. 1}, journal={ENVIRONMENTAL POLLUTION}, author={Aneja, VP and Roelle, PA and Robarge, WP}, year={1998}, pages={211–218} }
 @article{aneja_roelle_robarge_1997, title={Contribution of biogenic nitric oxide in urban ozone: Raleigh, NC, as a case study}, volume={31}, ISSN={["1352-2310"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0030616154&partnerID=MN8TOARS}, DOI={10.1016/S1352-2310(96)00282-8}, abstractNote={Anthropogenic emissions from industrial and automotive sources within the confines of the city of Raleigh, NC have been documented by the North Carolina Department of Environment, Health and Natural Resources, Division of Environmental Management, but no direct biogenic emissions of nitric oxide (NO) from soils has yet been measured. In this study, emissions of NO were measured in Raleigh, NC, and its surrounding suburbs, in an attempt to determine the portion of the total NOx ( = NO + NO2) budget which can be attributed to biogenic sources. Residential and commercial lawns, and golf courses receiving normal fertilizer applications were chosen as the primary biogenic source of NO. Soil NO fluxes were measured using a dynamic chamber technique from 11 sites and ranged in value (hourly averages calculated from 15 min readings) from 1.24 to 23.7 ng N m−2 s−1. These hour averages were then combined with estimates of lawn acreage within the city proper, and in the surrounding suburbs, in order to develop a budget for giogenic NO emissions in Raleigh. This budget was then compared to the budget used in the Environmental Protection Agency's (EPA) Regional Oxidant Model (ROM) for photochemical modeling. Results from this comparison suggest that less than 1 % of the total NOx budget for Raleigh, NC is emitted by natural processes, and that approximately 1.2% of the nitrogen applied as fertilizer is lost via soil NO emissions. Thus, the effects of biogenic NO may be neglected in the development of a reliable plan for reducing ozone in the urban atmosphere.}, number={10}, journal={ATMOSPHERIC ENVIRONMENT}, author={Aneja, VP and Roelle, P and Robarge, WP}, year={1997}, month={May}, pages={1531–1537} }