bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil Air Carbon Dioxide and Nitrous Oxide Concentrations in Profiles under Tallgrass Prairie and Cultivation
Authors: Sotomayor David , Rice Charles W. 
Published: July 2010

AbstractAssessing the dynamics of gaseous production in soils is of interest because they are important sources and sinks of greenhouse gases. Changes in soil air carbon dioxide (CO2) and nitrous oxide (N2O) concentrations were studied in a Reading silt loam (fine‐silty, mixed, mesic Typic Argiudolls) under prairie and cultivation. Concentrations were measured in situ over a 17‐mo period to a depth of 3 m. Multilevel samplers permitted collection of gases with subsequent measurement by gas chromatography in the laboratory. Soil air N2O concentrations were near atmospheric levels for a majority of the study period in the prairie site (0.184–2.25 µL L−1) but were significantly higher in the cultivated site (0.257–7.56 µL L−1). Annual mean N2O concentrations were 0.403 and 1.09 µL L−1 in the prairie and cultivated sites, respectively. Soil air CO2 annual mean concentrations were 1.56 × 104 and 1.10 × 104 µL L−1 and ranged from 0.096 × 104 to 6.45 × 104 µL L−1 and 0.087 × 104 to 3.59 × 104 µL L−1 in the prairie and cultivated sites, respectively. Concentrations generally increased with depth, with maximum soil air N2O and CO2 concentrations at 1.0 m in the prairie site and 0.5 m in the cultivated site. Nitrous oxide in the cultivated site and CO2 at both sites did not change markedly over winter months, but CO2 and N2O concentrations reached maximums during the summer months and decreased as the year progressed. Although soil air concentrations peaked and decreased faster at shallower depths, deeper depths exhibited relative maximum concentrations for longer time periods.
Water Quality Impacts by Golf Courses
Authors: Cohen Stuart , Svrjcek Amelia , Durborow Tom , Barnes N. LaJan 
Published: July 2010

AbstractInterest in water quality impacts by golf courses has grown significantly since the late 1980s due mostly to the local permitting process. Results from permit‐driven studies are frequently not published. Seventeen studies (36 golf courses) passed our review criteria and were incorporated into a detailed data review. A total of 16 587 data points from pesticide, metabolite, solvent, and NO3 analyses of surface water and ground water were reviewed. There were approximately 90 organics analyzed in the surface water database and approximately 115 organics in the ground water database. Widespread and/or repeated water quality impacts by golf courses are not happening at the sites studied. None of the authors of the individual studies concluded that toxicologically significant impacts were observed, although HALs, MCLs, or MACs were occasionally exceeded. The individual pesticide database entries that exceeded HALs/MCLs for ground water and surface water were 0.07 and 0.29%, respectively. The percentages would be somewhat higher if they could be expressed in terms of samples collected rather than chemicals analyzed. The MCL (10 mg/L) for nitrate—nitrogen (NO3—N) in surface water was not exceeded, and only 31/849 (3.6%) of the samples exceeded the MCL in ground water; however, most of the NO3 MCL exceedances were apparently due to prior agricultural land use. There was a slight trend for detected pesticides to be more persistent and more mobile than pesticides that were not detected, but the trend was not statistically significant. There are major data gaps in this review, particularly in the midcontinent area.
Temporal and Spatial Trends in Streamwater Nitrate Concentrations in the San Bernardino Mountains, Southern California
Authors: Fenn Mark E. , Poth Mark A. 
Published: July 2010

AbstractWe report streamwater nitrate (NO−3) concentrations for December 1995 to September 1998 from 19 sampling sites across a N deposition gradient in the San Bernardino Mountains. Streamwater NO3 concentrations in Devil Canyon (DC), a high‐pollution area, and in previously reported data from the San Gabriel Mountains 40 km northeast of Los Angeles, are the highest values reported in North America for undisturbed forest or shrub land watersheds. Concentrations in the primary stream draining western DC peaked at 350 µmol L−1 in December 1997 and minimum base flow NO−3 concentrations were nearly always ≥80 µmol L−1. In the San Gorgonio Wilderness (SGW), average NO−3 concentrations in four streams along the southern transect (moderate N deposition), ranged from 10 to 37 µmol L−1, while average NO−3 concentrations were ≤0.7 µmol L−1 in seven streams along the northern transect (low N deposition). Peak NO−3 concentrations in DC and in the SGW occurred after large winter storms, and a large spike in NO−3 concentrations (10–370 µmol L−1) in SGW Streams 1 to 5 was observed after thundershower activity in July 1997. Streamwater export of NO3‐N from Devil Canyon ranged from 3.6 to 11.6 kg ha−1 yr−1 during water years 1995 to 1998. This study further indicates that N emissions from fossil fuels and agriculture impact not only air quality, but also water quality from watersheds that are recipients of atmospheric N deposition.
A Multi‐Year Study of Four Herbicides in Surface Water of a Small Prairie Watershed
Authors: Rawn Dorothea F. K. , Halldorson Thor H. J. , Turner William N. , Woychuk Robert N. , Zakrevsky Jean‐Guy , Muir Derek C. G. 
Published: July 2010

AbstractTemporal trends of three phenoxy‐herbicides (2,4‐D, dichlorprop and MCPA) and bromoxynil were determined in the South Tobacco Creek, which drains a 70 km2 agricultural watershed near Miami, Manitoba, over a 4‐yr sampling program. The quantities of all pesticides used in the watershed and their application times were accurately recorded with the cooperation of landowners. Herbicide concentrations in South Tobacco Creek ranged from <0.01 ng/L to a maximum concentration of 680 ng/L (for 2,4‐D) and reflected local application times. Spring melt contributions were important when no significant runoff events occurred late in the previous growing season. Discharge of these herbicides in the South Tobacco Creek was calculated to be <0.01% of their quantities used within the watershed. No correlation was found between the water quality parameters: total organic C, total N, and total P and herbicide concentrations in South Tobacco Creek. Total N and P, however, were correlated to water flow, indicating runoff and ground water sources rather than atmospheric. We concluded that detailed temporal patterns of herbicides and nutrients could only be established if high sampling frequency was maintained during such critical periods such as application periods and during major runoff events. An unexpected finding was that herbicide concentrations were not related to runoff losses, but instead they did correspond to elevated levels in precipitation and air measured within the watershed.
Bacterial Reduction of Perchlorate and Nitrate in Water
Authors: Herman David C. , Frankenberger William T. 
Published: July 2010

AbstractA bacterial isolate, strain perclace, was shown to reduce the ground water contaminant perchlorate (ClO−4) to levels <0.005 mg L−1 when grown on acetate under anaerobic conditions. The ability of perclace to simultaneously reduce perchlorate and another ground water pollutant, nitrate (NO−3), was examined in batch studies and in a sand‐packed column under saturated flow conditions. Nitrate removal was monitored using ion chromatography, and perchlorate removal was monitored using a perchlorate specific electrode or ion chromatography, depending on the study. In batch studies, the reduction of 0.089, 0.92, 12.0, and 122 mg L−1 perchlorate was examined in the presence and absence of 62 mg L−1 NO3. Perchlorate was reduced more rapidly in the absence of NO−3 than in its presence. However, both perchlorate and NO−3 were reduced by more than 10‐fold within 48 h. A sand‐packed column (2.8 by 14 cm) inoculated with perclace simulated a flow‐through biotreatment system for water contaminated with a low level of perchlorate (0.130 mg L−1) and a much higher level of NO3 (125 and 20 mg L−1). Biotreatment could reduce perchlorate to <0.005 mg L in a 3 h residence time. The addition of NOr initially decreased the efficiency of perchlorate removal, however within 1 d the biotreatment system had adjusted such that there was complete removal of perchlorate and the reduction of NO−3 to <1 mg L−1.
Sizing Considerations for Gravel Beds Treating Acid Mine Drainage by Sulfate Reduction
Authors: Lyew Darwin , Sheppard John 
Published: July 2010

AbstractAn important consideration in the use of sulfate‐reducing bacteria (SRB) for treatment of acid mine drainage (AMD) is that SRB require a physicai support such as a gravel bed to become established. A quantitative method of describing the relationship between SRB activity and the physical parameters of the bed was investigated in a series of column reactors, as such information would be useful in the sizing of AMD treatment systems using SRB. This was accomplished by the use of ratios comprised of the amount of fresh AMD entering the system (Vc) and of physical parameters of the bed, namely the total surface area (tSA) of the gravel in the bed, the interfacial or superficial surface area (sSA) of the bed, and the void volume (Vv). Two numbers, D (= Vc/Vv, * sSA/tSA) and F (= Vv/Vc * sSA/tSA), were used in the analysis of the sulfate removal data obtained in column reactors. The sulfate removal data can be expressed either as the proportion of sulfate removed or the rate of sulfate removal. A relationship existed between the “proportion of sulfate removed” data and number D but not with F, while a relationship existed between the “rate of sulfate removed” data and number F, but not with D. This difference was due to the arrangement of the parameters in the numbers which reflected fundamental relationships between the physical environment and SRB activity. The relationships observed were that sulfate removal was optimal for D values between 0.0075 and 0.015, and that the rate of sulfate removal decreased as F‐values increased.
Seepage Losses and Nitrogen Export from Swine‐Waste Lagoons: A Water Balance Study
Authors: Ham Jay M. , DeSutter Tom M. 
Published: July 2010

AbstractSeepage losses from animal‐waste lagoons could affect ground water quality. Water balance methods were used to study seepage and N export from three swine‐waste lagoons in southwestern Kansas. Lagoons ranged in size from 0.8 to 2.2 ha and had an average waste depth of 5.6 m. Compacted soil liners were 0.30 to 0.46 m thick and built with native soil or, in one case, a soil‐bentonite mixture. Seepage was calculated from measurements of evaporation and changes in depth when the addition or removal of waste was precluded or quantified. Seepage rates were 1.1, 1.1, and 0.8 mm d−1 from the three lagoons, with the lowest rate occurring at the site with a 0.46‐m liner augmented with bentonite. The in situ coefficient of permeability of the soil liners ranged from 7.8 × 10−8 and 1.5 × 10−7 cm s−1. In two lagoons built with silt loam liners (no bentonite), permeabilities on a whole‐lagoon basis were about five times less than those measured from soil cores collected before the addition of waste. Results imply that permeability was reduced by organic sludge on the bottom of the lagoons. The average ammonium‐N concentration in the lagoons was 665 mg L−1, accounting for almost all of the soluble N. Calculations indicate that the ammonium‐N export rates were between 2187 and 2726 kg ha−1 yr−1, but more information is needed regarding the fate of N deposited in the soil beneath lagoons.
Soil and Stream‐Water Impacts of Sewage Effluent Irrigation onto Steeply Sloping Land
Authors: Speir T. W. , van Schaik A. P. , Kettles H. A. , Vincent K. W. , Campbell D. J. 
Published: July 2010

AbstractIn a pilot study, we investigated how irrigation of secondary sewage effluent onto steeply sloping land affected soil physical, chemical, and biochemical properties, the composition of soil‐ and surface‐waters and the vegetation on the site. The 3.36‐ha site received up to 44 mm effluent/wk (over a 7–11 h period), for 65 wk. Irrigation significantly improved total‐ and Olsen‐P status of the soils and greatly enhanced nitrification potential. Respiration increased with increasing soil water content, but microbial biomass was not greatly affected by irrigation. Soil phosphatase activity decreased with increasing P fertility. Soil physical properties were not affected by effluent and hydraulic conductivities were sufficient to conduct water into and through the soil profiles. Soil‐ and surface‐water NO−3‐N concentrations increased markedly, especially in the second half of the trial when soil nitrification rates were also high. However, the streamwater NO3‐N concentrations remained well below the drinking water limit concentration of 11.3 g m−3. In contrast, streamwater NH+4‐N and PO3−4‐P concentrations remained low and results indicated that concentrations of PO3−4‐P in river water, resulting from a full‐scale irrigation scheme, would not exceed the target limit level of 0.0056 g m−3. Irrigation accelerated natural successional changes in the vegetation, with a decline in undesirable fire‐prone and shrnbby species and an increase in native trees and tree ferns. These results demonstrated that, in the short term at least, a carefully designed and implemented irrigation scheme on steepland could renovate secondary sewage effluent, without adversely affecting soil properties and surface water quality.
Degradation of 2,4‐D, 2,4‐Dichlorophenol, and 4‐Chlorophenol in Soil after Sorption on Humified and Nonhumified Organic Matter
Authors: Benoit P. , Barriuso E. , Soulas G. 
Published: July 2010

AbstractSoil organic matter (SOM) primarily governs sorption processes and therefore affects the availability of organic chemicals to degrading microorganisms. Transformations of 14C‐ring‐labeled 2,4‐dichlorophenoxyacetic acid (2,4‐D); 2,4‐dichlorophenol (2,4‐DCP); and 4‐chlorophenol (4‐CP) sorbed on organic materials with increasing degrees of humification (wood, fresh straw, composted straw, lignin, and humic acid) and on a reference mineral sorbent (Al‐oxide) were studied during soil incubation experiments. Chemicals previously sorbed on the different sorbents were applied to the soil. Mineralization kinetics, analysis of water and methanol extracts and measurements of the nonextractable radioactivity before and after soil incubation were done to characterize changes in the availability of sorbed 14C chemicals. Mineralization of 2,4‐D was higher than mineralization of 2,4‐DCP and 4‐CP: depending on the nature of the sorbent, 47 to 87% of 2,4‐D, 10 to 68% of sorbed 2,4‐DCP and 12 to 65% of sorbed 4‐CP were mineralized. Specific metabolic transformations and formation of bound residues occurred principally with the less humified organic sorbents. The formation of bound residues from the three chemicals was high after sorption on composted straw, where bound residues accounted for 20, 23, and 78% of applied 2,4‐D; 2,4‐DCP; and 4‐CP, respectively. This was attributed partially to the initial sorption‐desorption characteristics but was also explained by transformations that had occurred on this decomposing organic material. Our results showed that protection of chemicals against biodegradation by sorption processes can not be generalized since in most of the cases studied sorption induced an increase of mineralization rate.
Tillage Effects on Persistence and Distribution of Trifluralin in Soil
Authors: Berger Bernhard M. , Dühlmeier Detlef , Siebert Christina F. 
Published: July 2010

AbstractThe aim of this study was to investigate the effects of the substitution of plowing with harrowing—twice in a 3‐yr crop rotation—on persistence and distribution of a persistent herbicide such as trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) to rate these two tillage systems for their environmental impact (e.g., regarding potential ground water contamination with pesticides). Therefore, studies have been performed in Germany at two sites, a clayey silt in Reinshof and a loamy sand in Eickhorst. The herbicide was applied to oilseed rape (Brassica napus L. var. napus), followed in consecutive years by applications to wheat (Triticum aestivum L.) or to wheat followed by rye (Secale cereale L.). The disappearance time of 50% of the initial concentration (DT‐50 value) decreased from >300 d after preplant incorporation of trifluralin to <150 d after pre‐emergence treatment, losses being greater due to volatilization resulting from the lack of soil incorporation. No influence of different tillage systems on trifluralin persistence could be observed. Distribution of the herbicide in the top 30 cm of the soils, however, was significantly influenced by the soil cultivation systems. Reduced tillage (harrowing) in two consecutive years resulted in trifluralin concentrations in the soil layers 10 to 20 cm and 20 to 30 cm under the limit of determination (0.005 mg kg−1). In contrast, plowing led to trifluralin residues of up to 0.019 mg kg−1 in these soil layers. Although no trifluralin residues could be found in the 30‐ to 45‐cm and 45‐ to 60‐cm soil layers under either soil cultivation system, our results imply an increased risk of ground water contamination after plowing.
Phosphorus and Nitrogen in Runoff following Beef Cattle Manure or Compost Application
Authors: Eghball Bahman , Gilley John E. 
Published: July 2010

AbstractManure or compost from beef cattie feediots can be an excellent sources of nutrients and organic matter when added to soils, but they can also pollute runoff. We determined the effects of simulated rainfall on runoff losses of P and N, and EC and pH following application of manure and compost to a Sharpsburg silty clay loam (fine smectitic, mesic Typic Argiudoll) soil having grain sorghum [Sorghum bicolor (L.) Moench] and winter wheat (Triticum aestivum L.) residues. Manure, compost, and fertilizer were applied to no‐till fields at rates required to meet N or P requirements for corn (Zea mays L.) production and were either left on the soil surface or disked to 8 cm. There were also untreated checks. Runoff concentrations of dissolved P (DP), bioavailable P (BAP), and NH4‐N were significantly greater when the soil was not disked. Total and particulate P concentrations in runoff were generally less under wheat than sorghum residue and were less for the no‐till than the disked condition. In the disked system, N or P‐based manure or compost application resulted in DP concentration <1 mg L−1. Manure and compost application resulted in greater runoff EC values than fertilizer application. Phosphorus concentration of runoff receiving P fertilizer or N‐based manure and compost application can be an environmental concern when these sources are applied under no‐till conditions without incorporation.
Spatial—Temporal Variability of Preferential Flow in a Clay Soil under No‐Till and Plow‐Till
Authors: Ogden C. B. , van Es H. M. , Wagenet R. J. , Steenhuis T. S. 
Published: July 2010

AbstractTillage most affects the large pore spaces, including macropores, which dominate percolation through field soils. Rain events are expected to promote post‐tillage changes in pore geometry. Pore‐geometric influences on macropore transport were examined under multiple rains, in a Kingsbury clay soil under no‐till (NT) and plow‐till (PT). Four replicate pairs of large undisturbed sample columns were installed on grid wick iysimeters comprising 5 × 5 grids of 36‐cm2 cells. Five simulated rains having mean depths and intensifies of 40 mm and 38 mm h−1, respectively, were applied, separated by intervals of 4, 8, 9, and 50 d, using a constant‐head drop‐forming rainfall simulator. Atrazine [6‐chloro‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine] and a Br− tracer were applied 24 and 1 h, respectively, before the first rain. Persistence of spatial percolation patterns was quantified by inter‐event correlation coefficients of the cell‐scale water outflows. Outflow was significantly greater in NT than in PT, averaging 75 and 54% of applied rain, respectively, but Br− export did not differ significantly between them. Spatial outflow patterns changed between events in both tillage treatments and were more variable in NT. Distributions of cell‐scale cumulative change in outflow proportion were unimodal and symmetric. Percolation in NT occurred as bypass flow through direct pathways, relative to PT pathways characterized by mixing. Transport variability due to temporal variability of functional macropore flowpaths may account for some solute tailing in field soils.
Global Sensitivity Analyses of Three Pesticide Leaching Models Using a Monte‐Carlo Approach
Authors: Soutter Marc , Musy André 
Published: July 2010

AbstractThe modeling of large natural systems requires a lot of data, carries a considerable amount of uncertainties and involves a significant computational effort. A global parameter sensitivity analysis, accounting for simultaneous parameter variations over their entire admissible ranges, is therefore potentially useful at all stages of the modeling process. The sensitivity analysis presented in this paper were carried out within the frame of a regional vulnerability assessment regarding ground water contamination by pesticides. The three selected pesticide leaching models include an analytical solution of the convection‐dispersion equation (attenuation factor, AF), a tipping bucket model (LEACHA), and a numerical solution of the convection‐dispersion equation (LEACHM). Sensitivity analysis was performed with a Monte‐Carlo based technique involving Latin hypercube sampling along with multiple regression. The results show that the parameters controlling degradation and sorption processes are far more important than those accounting for the transport process. Actually, pesticide properties (degradation rate and partition coefficient), organic C content and water table depth are the most predominant variables regarding cumulated (10 yr) pesticide fluxes to the ground water. Unexpectedly, variables such as soil hydrodynamic properties, dispersivity, or pesticide solubility did not have a significant effect on the magnitude of cumulated pesticide fluxes. As a consequence, in a stochastic approach to regional‐scale ground water vulnerability assessments, the probability density functions of those variables may be chosen empirically or according to a classification of soils combined with pedotransfer functions, without affecting significantly the resulting assessment maps and their uncertainties.
Effects of Soil Moisture, Depth, and Organic Amendments on Selenium Volatilization
Authors: Zhang YiQiang , Frankenberger William T. 
Published: July 2010

AbstractEffects of soil moisture, depth, and organic amendments on selenium (Se) volatilization in a Se‐contaminated soil were studied in three different experiments. Results showed that the volatilization rate of Se as dimethylselenide (DMSe) was increased during a transition from air‐dry soil (<2 µg/m2 per day) to a wetted soil (185 µg/m2 per day), and was also much higher after rewetting an air‐dried soil than keeping the soil continuously moist. Although more DMSe was produced with increasing soil mass, DMSe was trapped in the subsoil layers. DMSe emission to the air was related to the moisture content. After 10 d, 96 and 14% of injected DMSe was volatilized to the air from an air‐dried soil and a water‐saturated soil, respectively. Both insoluble (casein) and soluble (Casamino acids) organic amendments enhanced DMSe production and removal from soil through volatilization. This study suggests that organic amendments and frequent tillage are needed to increase Se volatilization from soil by enhancing production of DMSe and increasing soil porosity in facilitating the diffusion of trapped DMSe to the atmosphere.