bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential Movement of Dithiopyr following Application to Golf Courses
Authors: Hong Song , Smith A. E. 
Published: July 2010

AbstractResearch was conducted to evaluate the potential movement of dithiopyr [S,S‐dimethyl2‐(difluoromethyl)‐4‐(2‐methylpropyl)‐6‐(trifluoromethyl)‐3,5‐pyridinedicarbothioate] from golf courses. Dithiopyr was applied as granule and emulsifiable concentrate (EC) formulations to ‘Penncross’ creeping bentgrass (Agrostis stolonifera L.) and ‘Tifdwarf’ hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] in simulated greens. Less than 0.6% of the dithiopyr was transported through the rooting media (a mixture containing at least 97% coarse sand by weight with sphagnum peat moss). Dithiopyr concentrations in the leachate, transported through the greens, did not exceed 3 µg L−1. Most of the dithiopyr (11–31%) was detected in the top 0 to 12.5 cm of rooting media at the end of the greenhouse experiments and as much as 20% of the applied dithiopyr was removed with the leaf clippings over the duration of the greenhouse experiments. The highest concentration of dithiopyr transported in the runoff water from simulated golf course fairways did not exceed 40 µg L−1. Generally, the concentration of dithiopyr in the runoff water was higher when applied as an EC formulation compared with the granule formulation at 1 d after treatment (DAT). The dithiopyr concentration, in the runoff water, had decreased to near 9 µg L−1 at the 8 DAT sampling period and less than 2.0% of the applied dithiopyr was transported from the simulated fairways.
Sorption and Desorption of Atrazine, Deethylatrazine, and Hydroxyatrazine by Soil and Aquifer Solids
Authors: Moreau C. , Mouvet C. 
Published: July 2010

AbstractAdsorption kinetics and adsorption/desorption isotherms of atrazine (AT), and its degradation products, deethylatrazine (DEA) and hydroxyatrazine (HyA) on solids from two depths of a gleyic planosol and the underlying sandy aquifer were studied using laboratory batch systems. Adsorption of the three molecules decreased with the sampling depth of the solid. Atrazine and DEA were not adsorbed on the aquifer solids, whereas HyA was. For all three solids, the adsorption increased in the order DEA < AT << HyA. Adsorption equilibrium was reached after 72 h for the upper soil sample (0‐0.33 m) and after 24 h for the deeper soil sample (0.9–1.05 m) for all three molecules. For HyA, equilibrium was reached after 24 h for the aquifer solid (6–7 m). High pressure liquid chromatography (HPLC) analyses showed no significant degradation of the three molecules after 72 h. The adsorption isotherms of the three molecules were described by Freundlich equations. The Kfads values ranged from 3.1 to 0.4 L kg−1 for AT, 1.5 to 0.3 L kg−1 for DEA and 7.9 to 0.9 L kg−1 for HyA. The Koc values suggested that the affinity for the organic matter bound to the solid increased in the order DEA < AT << HyA. The desorption isotherms were also described by Freundlich equations. The Kfdes value was 7.5 L kg−1 for AT in the upper soil sample and ranged from 0.1 to 31.1 L kg−1 for DEA and from 0.7 to 96.8 L kg−1 for HyA, depending on the sample. In the upper soil sample, desorption was hysteretic and DEA and HyA formed nonextractable residues, HyA more so than DEA. For the deeper soil sample for all three compounds and the aquifer solids for HyA, adsorption was completely reversible and did not lead to the formation of nonextractable residues.
Destruction of 2,4,6‐Trinitrotoluene by Fenton Oxidation
Authors: Li Z. M. , Comfort S. D. , Shea P. J. 
Published: July 2010

AbstractPast disposal practices at munitions production facilities have generated numerous acres of 2,4,6‐trinitrotoluene (TNT)‐contaminated soil. We determined the potential of the Fenton reagent (Fe2+ and H2O2) to remediate TNT contamination in water, aqueous extracts of contaminated soil, and soil‐water slurries. The effects of H2O2 and Fe2+ concentrations, solution pH, temperature, and initial TNT concentration on transformation and mineralization rates were evaluated. Treating an aqueous TNT solution (70 mg TNT L−1) with Fenton reagent (1% H2O2, 80 mg Fe2+ L−1) in the dark resulted in 100% destruction of TNT within 24 h. This coincided with 40% mineralization. Subsequent exposure to light resulted in >90% mineralization. We observed generation of 2,4,6‐trinitrobenzoic acid and 1,3,5‐trinitrobenzene within 15 min following Fenton oxidation of TNT. This indicates that initial TNT destruction likely occurs by methyl group oxidation and decarboxylation. Subsequent transformations involve nitro moiety removal with ring hydroxylation and cleavage, as evidenced by the stoichiometric recovery of TNT‐nitrogen as NO−3 and production of oxalic acid as the primary C‐containing end product. Upon exposure to light, Fe(II) was regenerated and the oxalate produced from 14C‐TNT oxidation disappeared; this coincided with a decrease in solution 14C activity. Similar observations were made when 14C‐oxalic acid was the starting substrate. Fenton oxidation was also effective in destroying TNT in aqueous extracts of contaminated soil and soil‐water slurries. Experimental data provide evidence that the Fenton reagent can effectively remediate TNT‐contaminated water and soil.
Anaerobic Transformation of Alachlor, Propachlor, and Metolachlor with Sulfide
Authors: Stamper David M. , Traina Samuel J. , Tuovinen Olli H. 
Published: July 2010

AbstractThe purpose of this work was to elucidate microbiological and abiotic transformations relevant to the environmental fate of the acetanilide herbicides alachlor [2‐chloro‐2′,6′‐diethyl‐N‐methoxymethyl)acetanilide], propachlor (2‐chloro‐N‐isopropyl‐acetanilide), and metolachlor [2‐chloro‐2′‐ethyl‐6′‐methyl‐N‐(1‐methyl‐2‐methoxyethyl)‐acetanilide]. Several attempts to retrieve aerobic and anaerobic microbial cultures capable of degrading alachlor from agricultural soils and pond sediments were unsuccessful with the exception of sulfate‐reducing bacteria that partially transformed acetanilide herbicides during active sulfate reduction. The transformation products of alachlor and propachlor were more hydrophobic than the parent compounds. The transformations were associated with the activity of sulfate‐reducing bacteria because the reactive species was sulfide and possibly other reduced S species produced during the bacterial reduction of sulfate. Transformation could be duplicated under abiotic conditions by reacting Na2S with alachlor, propachlor, and metolachlor. One of the reaction products of the abiotic reaction between alachlor and sulfide was identified by mass spectroscopy as a S‐substituted dimer of alachlor. This compound was formed by the nucleophilic substitution of chloride by reduced S, with the subsequent oxidation to a disulfide.
Consequences of Rising Atmospheric Carbon Dioxide Levels for the Belowground Microbiota Associated with White Oak
Authors: Ringelberg David B. , Stair Julia O. , Almeida Jonas , Norby Richard J. , O'Neill Elizabeth G. , White David C. 
Published: July 2010

AbstractThe consequences for belowground microbiota under conditions of rising atmospheric CO2 are largely unknown. In this research we examined the microbiota associated with white oak (Quercus alba L.). It was our hypothesis that an increase in CO2 level would induce a change in the rhizosphere‐associated microbial abundance and community composition. To provide an in situ estimation of microbial abundance and community composition, ester‐linked polar lipid fatty acid (PLFA) technology was utilized. This technology, based on the quantitative measurement of membrane lipid fatty acids, has been utilized in the accurate identification and description of bacterial isolates and communities. Initial experiments demonstrated that a clear distinction in lipid patterns and microbial biomass existed between sterile roots and those of roots containing an associated viable microbiota. Statistical approaches were then used to determine what differences existed between individual PLFA and PLFA patterns obtained from white oak fine roots and bulk soils. An analysis of variance (ANOVA) showed significant differences to exist in the relative percentages of individual prokaryotic PLFA collected under ambient vs. elevated CO2 and between those associated with fine roots and bulk soils. Multivariate statistics showed distinct differences in the patterns of prokaryotic PLFA detected in the rhizosphere vs. the surrounding bulk soil, but did not identify differences related to elevated CO2 exposures. An artificial neural network recognized PLFA patterns unique to three different CO2 exposures: ∼35, ∼50, and ∼65 Pa. Results of the three statistical tests were viewed as supportive of the hypothesis describing significant differences in individual PLFA and patterns of PLFA as a result of elevated CO2 exposure.
Spatial Variability of Canopy Throughfall and Groundwater Sulfate Concentrations under a Pine Stand
Authors: Böttcher J. , Lauer S. , Strebel O. , Puhlmann M. 
Published: July 2010

AbstractCalculation of solute flux into groundwater by recharge must account for the spatial variability of water flux and recharge solute concentration. Solute concentration of the recharge can be characterized by sampling the uppermost groundwater. In an earlier study under pine (Pinus silvestris L.) on sandy soil, solute concentrations at the water table along a transect fluctuated in a recurrent pattern, probably caused by heterogenous solute input via canopy throughfall. To obtain more insight into the spatial variability of deposition processes and solute concentrations in recharge, transect sampling of the uppermost groundwater was repeated in 1989, and again in 1993. Solute deposition by throughfall was also measured in 1993. The data were analyzed by spectral and time series methods. Sulfate (SO4) concentrations in canopy throughfall and uppermost groundwater showed recurrent fluctuations corresponding to canopy coverage of the ground. Sulfate maxima coincided with canopy edges. The dominant fluctuation frequency of SO4 concentrations in 1993 was lower than in 1989 because of canopy enlargement by pine tree growth. Detailed analysis of the 1993 SO4 concentrations revealed superimposed fluctuations with a frequency valid for the 1989 canopy edge distribution. This can be attributed to an actual patterned SO4 retrieval from solid aluminum‐hydroxo‐sulfate (Al‐OH‐SO4) phases, stored in the subsoil under previous higher SO4 deposition rates.
Trace Metal Geochemistry in Spodosols of the Northeastern United States
Authors: Jersak Joseph , Amundson Ronald , Brimhall George 
Published: July 2010

AbstractLong‐term or postglacial (≈ 12 000‐year) net fluxes of Pb, Cu, Zn, Ni, Cr, and Co through three Spodosols, formed from different parent materials, were calculated using mass‐balance modeling. Metal contents in vegetation and O horizons were also estimated and measured, respectively. Total metal contents in mineral horizons were fractionated into different operationally defined pedogenic phases using a sequential extraction technique. With few exceptions, the three soils had significant leaching losses for all trace metals (from 7–508 kg ha−1), the greatest losses generally occurring in the E and upper horizons. The magnitude of losses by leaching varied with parent material, as a result of differences in weatherabilities of mineral suites. Combined metal contents in vegetation and O horizons, which may originate from anthropogenic additions as well as mineral weathering, are significantly large in some cases; however, these metal amounts are apparently not large enough to offset long‐term leaching losses from the underlying mineral soil profiles. Some B and C horizons had net accumulations of extractable Pb, Cu, and/or Ni‐bearing phases. Based on the sequential extraction procedure used, the extractable metal forms are probably pedogenic Fe oxide‐ and/or organic‐bound phases. One soil apparently gained Cu (≈38 kg ha−1), which may have been from atmospheric deposition.
A Novel Approach Using Solid Phase Extraction Disks for Extraction of Pesticides from Water
Authors: Koskinen W. C. , Barber B. L. 
Published: July 2010

AbstractPressures to reduce hazardous solvent use in traditional procedures for pesticide extractions from water have increased the use of solid phase extraction (SPE) technology. We have expanded the use of SPE disks beyond the procedural techniques previously used. Pesticides are sorbed onto preconditioned SPE disks placed directly into the water in the sample collection bottle and then eluted off the disks by solvents in the same bottle, bypassing the laboratory extraction process and reducing costs by eliminating the need for expensive vacuum filtering glassware. We determined atrazine (6‐chloro‐N‐ethyl‐N′‐[1‐methylethyl]‐1,3,5‐triazine‐2,4‐diamine), acetochlor (2‐chloro‐N‐[ethoxymethyl]‐N‐[2‐ethyl‐6‐methylphenyl]acetamide), and alachlor (2‐chloro‐N‐[2,6‐diethylphenyl]‐N‐[methoxymethyl]acetamide) recovery from water as a function of contact time, degree of mixing, and disk size. Shaking 47‐mm C8 extraction disks in 500 mL water for 20 h, followed by elution with ethyl acetate in the same sample collection bottle, resulted in >70% recovery of the three herbicides (1 µg L−1) compared to >90% recovery for atrazine achieved with traditional vacuum‐filtering extraction. This research suggests a simpler approach for pesticide extraction from water samples compared to current methods, and may allow for in‐field extraction of some pesticides.
Postwar Nitrogen Use Efficiency in West German Agriculture and Groundwater Quality
Authors: van der Ploeg R. R. , Ringe H. , Machulla Galina , Hermsmeyer D. 
Published: July 2010

AbstractRising NO3 concentrations in groundwater are of general concern in Germany. To estimate the role that agriculture has played in this contamination, national statistical data on fertilizer and fodder use and on agricultural productivity for 1951 to 1990 were analyzed. With use of assumptions about the N content of fertilizers, fodder, and agricultural products, an attempt was made to estimate the yearly N turnover and N‐use efficiency in West German agriculture during this period. The analysis showed that from 1951 to 1990 the use of commercial N fertilizer increased from 27.4 to 107.8 kg ha−1 and of N present in animal feeds from 72.4 to 158.0 kg ha−1. At the same time, the estimated N content of farm produce only increased from 24.1 to 57.2 kg ha−1. As a consequence, agricultural N surplus increased from 7.2 kg ha−1 in 1951 to 94.6 kg ha−1 in 1990. The analysis also showed that during the 1951 to 1990 period, N‐use efficiency in crop production decreased from 100% in 1951 to 81.4% in 1990. Nitrogenuse efficiency in livestock production changed little and varied time‐independently between 12.4 and 17.3%. For agriculture as a whole, N‐use efficiency decreased from 77.0% in 1951 to 38.0% in 1990. The results indicate that low N‐use efficiency in livestock production, together with an excess of farm manure, is the main reason for the NO3 problem that Germany is facing.
A Quantitative Estimation of the Complexation of Small Organic Molecules with Soluble Humic Acids
Authors: Clapp C. E. , Mingelgrin U. , Liu R. , Zhang H. , Hayes M. H. B. 
Published: July 2010

AbstractSmall organic molecules, such as the commonly used herbicides napropamide [N,N‐diethyl‐2‐(1‐naphthyloxy) propionamide] and atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine), complex with soluble humic acids (HAs), producing a marked effect on apparent solubility, availability, and mobility. The overall objective of the present paper is to propose a procedure by which the extent of complexation of small organic molecules with stable humic acids can be quantitatively estimated. Experiments were carried out to investigate the effects of HA and herbicide concentrations, pH, and ionic composition and strength on the extent and nature of complexation using an equilibrium dialysis procedure and 14C‐labeled herbicides. The relative strength of complexes of napropamide with a series of HAs from a wide range of sources, determined at a concentration of 2.0 mg HA mL−1, was in the order of soil > peat > water. Complexation of the herbicides with the soil HA was greater for napropamide than for atrazine (Kc at pH 6.5, 0.83 and 0.12 mL mg−1, respectively). As solubility of molecules in water increases, complex formation usually decreases. However, the complexation of napropamide and atrazine did not correlate inversely with their solubility. Environmental conditions, such as pH and ionic strength and composition, as well as the source of the HAs, had a strong effect on the complexation of the investigated pesticides. The relationship between complexation and the above factors suggests that it is their effect on coiling of the HA strands, which determines the extent of complexation.
Removal of Atrazine from Aqueous Solution by Natural and Activated Bentonite
Authors: González‐Pradas E. , Villafranca‐Sánchez M. , Gallego‐Campo A. , Ureña‐Amate D. , Fernández‐Pérez M. 
Published: July 2010

AbstractTo evaluate the potential use of bentonite in removing atrazine [2‐chloro‐4‐ethylamino‐6‐isopropilamino‐1,3,5‐triazine] from water, the adsorption of atrazine on bentonite desiccated at 383 K untreated, and acid‐treated with H2SO4 solutions over a concentration range between 0.25 × 103 cmol L−1 and 1.00 × 103 cmol L−1, from aqueous solution at 303 K has been studied by using batch experiments. In addition, column experiments were carried out with the bentonite samples treated with the 1.00 × 103 cmol L−1 H2SO4 [B‐A (1.00)] using two aqueous atrazine solutions at C = 5.91 mg L−1 and C = 9.78 mg L−1 concentrations. The experimental data points have been fitted to the Langmuir equation to calculate the adsorption capacities (Xm). Values for Xm ranged from 0.07 g kg−1 for the untreated bentonite up to 13.4 g kg−1 for the [B‐A (1.00)] samples. The removal efficiency (R) ranged from 2.71% for the B‐N up to 83.5% for B‐A (1.00). The batch experiments show that the acid‐treated bentonite is more effective than the natural bentonite in relation to the adsorption of atrazine. The column experiments show that the B‐A (1.00) sample might be reasonably used in removing atrazine, the column efficiency increasing from 47.5% for the C = 9.78 mg L−1 aqueous solution of atrazine up to 63.4% for the C = 5.91 mg L−1 one.
Herbicide Contamination of Prairie Springs at Ultratrace Levels of Detection
Authors: Wood John A. , Anthony Donald H. J. 
Published: July 2010

AbstractNatural springs provide an opportunistic subject for assessing aquifer contamination. To determine the frequency and level of aquifer contamination by herbicides in the Canadian prairie, a study of natural springs draining small surficial aquifers a few hectares in area was carried out in southern Saskatchewan. All but one of the aquifers investigated received herbicide applications either for agricultural purposes or brush control. Elevated tritium isotope activities (10–60 TU) confirmed recent recharge of these aquifers. No wells were present on these aquifers. Therefore, the possibility of contamination by direct entry down wells was eliminated from the study. Large volume extraction technology permitted detections of herbicides at ng L−1 levels. This is the first study of herbicides in natural springs in Canada. Herbicides were detected in 23% of samples collected. The most frequently detected analytes being atrazine (6‐chloro‐N2‐ethyl‐N4‐(isopropyl)‐1,3,5‐triazine‐2,4‐diamine), picloram (4‐amino‐3,5,6‐trichloropicolinic acid) and 2,4‐D ((2,4‐dichlorophenoxy)acetic acid), with detections in 12, 7, and 7% of samples collected, respectively. The results show that shallow aquifer contamination occurs in the absence of wells. However, the levels detected were in the ng L−1 (ppt) range, which is much less than levels commonly reported in most well surveys. None of the herbicide concentrations exceeded any guidelines for drinking water, livestock, irrigation, and aquatic life including Canadian, Provincial, World Health Organization, and USEPA guidelines.
Runoff of Two Sulfonylurea Herbicides in Relation to Tillage System and Rainfall Intensity
Authors: Afyuni M. M. , Wagger M. G. , Leidy R. B. 
Published: July 2010

AbstractThe use of sulfonylurea herbicides is increasing because they are used at very low rates and offer greater weed management flexibility in pre‐ and postemergence programs. Information is needed on the off‐site movement of these compounds under different tillage systems. Our objective was to evaluate the runoff potential of chlorimuron ethyl {(2‐[[[[(4‐chloro‐6‐methoxy‐pyrimidin‐2‐yl) amino]carbonyl]‐amino]sulfonyl] benzoic acid)}, nicosulfuron {(2[[(4,6‐dimethoxypyrimidin‐2‐yl) aminocarbonyl]aminosulfonyl]‐N, N‐dimethyl‐3‐pyridinecarboxamide)}, and bromide in conventional (CT) and no‐tillage (NT) production systems under simulated rainfall. The soil types were a Norfolk sandy loam (fine‐loamy, siliceous, thermic Typic Paleudult) at a Coastal Plain location and a Pacolet sandy clay loam (clayey, kaolinitic, thermic Typic Kanhapludult) at a Piedmont location. The first simulated rainfall event (30 min) consisted of a low (1.27 cm h−1) or high (5.08 cm h−1) rate applied 24 h after herbicide and bromide application. One week later, the high rainfall rate was repeated on all plots. Consistently greater runoff occurred with CT compared to NT. Runoff differences between tillage systems were more pronounced for the second rainfall simulation and also with the Piedmont soil. The average herbicide losses from the initial high rainfall simulation were 1.2 and 2.2% of the total application (0.014 kg ha−1) for CT and NT, respectively, at the Coastal Plain location. Similar results were obtained at the Piedmont location. Mean herbicide losses during the second rainfall simulation represented <0.2% of the applied rate. There were no detectable concentrations of either herbicide found in the sediment phase of runoff. On the basis of these results, it is not expected that chlorimuron or nicosulfuron pose a significant threat to the environment via transport in runoff.
Sorption and Degradation of Alachlor in Soil and Aquifer Material
Authors: Clay S. A. , Moorman T. B. , Clay D. E. , Scholes K. A. 
Published: July 2010

AbstractHerbicides may contaminate groundwater when used over shallow aquifers. Alachlor [2‐chloro‐N‐methoxymethyl‐N‐(2,6‐diethylphenyl)‐acetamide] is widely used in corn (Zea mays L.) and soybean (Glycine max L.) for grass control in eastern South Dakota where depth to groundwater ranges from <2 to >20 m. Sorption and degradation of alachlor, two processes that control its fate in the environment, were measured in laboratory batch equilibrium and incubation studies. Surface soil and sediment samples from above and below the water table (∼6 m below the soil surface) were collected following aseptic procedures. Alachlor sorption to the surface A horizon soil (silty clay loam) was about 13 times greater than sorption to the 2C horizon soil (sand and gravel). About 2.5% of the alachlor was completely mineralized after 112 d in surface soil, whereas <0.5% was mineralized in the 2C horizon soils. The addition of C (lyophilized algae biomass) increased ring mineralization and polar metabolite formation in all samples. These data indicate that bacterial populations in the Big Sioux aquifer are sufficiently diverse to degrade complex organic molecules. Carbon was the factor most limiting alachlor metabolism in subsurface sediments.