bluuebunny/crossref_metadata_2025_split huggingface dataset:
Removal of Atrazine and Deisopropylatrazine from Water by Montmorillonite‐Phosphate Crosslinked Compounds
Authors: González‐Pradas E. , Villafranca‐Sánchez M. , Del Rey‐Bueno F. , Ureña‐Amate M. D. , Fernández‐Pérez M. 
Published: July 2010

AbstractTo assess the potential use of two montmorillonite‐(cerium [Ce] or zirconium [Zr]) phosphate crosslinked compounds in removing organic pollutants from water, the adsorption of atrazine (6‐chloro‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine) and one of the major metabolites of atrazine in water, deisopropylatrazine (6‐chloro‐N4‐ethyl‐1,3,5‐triazine‐2,4‐diamine), has been studied at 25°C using batch experiments. The influence of the presence of 0.01 M KCl in the medium was also investigated for a better understanding of variables affecting the adsorption of these organic compounds. Experimental data points have been fitted to the Langmuir equation, with the results indicating a higher adsorption for deisopropylatrazine than for atrazine on both adsorbents in saline and nonsaline medium. Variation of the uptake of atrazine and the metabolite in the solution of 0.01 M KCl shows an enhanced adsorption of deisopropylatrazine on both samples compared w th that of atrazine. Fourier‐transformed infrared (FTIR) spectroscopic studies reveal that at the pH generated by the adsorbents (3.7 and 3.9 for Ce and Zr—montmorillonite compounds, respectively), atrazine and its metabolite interact with the surface of the adsorbents. X‐ray diffraction analysis showed that the compounds studied are intercalated into the adsorbents. For the compounds considered, the cerium—montmorillonite adsorbent shows a higher capacity of adsorption compared with zirconium—montmorillonite adsorbent, so it might be particularly useful in removing atrazine and, to a greater extent, deisopropylatrazine from water.
Mechanism of Degradation of Methyl Bromide and Propargyl Bromide in Soil
Authors: Papiernik Sharon K. , Gan Jianying , Yates Scott R. 
Published: July 2010

AbstractThe degradation of methyl bromide (MB) and propargyl bromide (PB) was investigated in soil and water to obtain information on the mechanism of degradation. It has been suggested that primary alkyl halides (including MB and the potential alternatives PB and methyl iodide) can undergo SN2 nucleophilic substitution with nucleophilic sites on soil organic matter (i.e., ‐NH2, ‐NH, ‐OH, ‐SH). The pattern of product formation observed in this study provides more direct evidence that fumigants that are primary alkyl halides can alkylate soil organic matter and that this may be a significant mechanism of degradation in soil. Degradation in water samples (hydrolysis) formed Br− and the corresponding alcohol (propargyl alcohol from PB, methanol from MB) in equimolar amounts. The rate of hydrolysis was not significantly different from the rate of Br− formation for both MB and PB. Degradation in two soils resulted in the formation of Br−, but very little production of the corresponding alcohol, indicating that some mechanism other than hydrolysis must be occurring in the soil. Degradation of MB and PB was much more rapid in the higher‐organic‐matter clay loam soil than in the sandy loam soil. Spiking 14C‐labeled MB to soil resulted in the formation of nonextractable (soil‐bound) 14C, which increased as the extractable 14C decreased. Microbial oxidation was not significant in these soil samples, which were sterilized through autoclaving and/or treatment with high concentrations of fumigants. These results provide further experimental evidence that MB, PB, and similar compounds can alkylate soil organic matter.
Strychnine Uptake by Cereals and Legumes Grown in the Glasshouse and Field
Authors: Oliver D. P. , Kookana R. S. , Rogers S. L. , Sinclair R. G. , Roberts G. , Cook C. 
Published: July 2010

AbstractStrychnine‐coated wheat grain was used as bait in broad‐acre agriculture in Australia to control severe mouse damage during 1993 to 1995. To establish whether plants could take up strychnine, glasshouse experiments were conducted on wheat (Triticum aestivum L.), barley (Hordeum vulgare L), lupine (Lupinus angustifolius L.), pea (Pisum sativum L.) and faba‐bean (Vicia faba L.). Strychnine uptake was also determined by growing plants from germinated baits. In the glasshouse experiments strychnine was detected in lupine grain (<80–2500 µg kg−1) and in straw from wheat, barley, pea, faba‐bean, and lupine (<40–390 µg kg−1) when these plants were grown adjacent to 1 or 3 baits, equivalent to 36 to 107 times the recommended field rate, respectively. Strychnine was also detected in straw from the germinated baits (<40–2233 µg kg−1). Field experiments were then conducted to study strychnine uptake by wheat, barley, lupine, chickpea (Cicer arietinum L), pea, and canola (Brassica napus var. napus) under more realistic conditions. In the field strychnine was detected in only 3 samples of pea straw (10, 24, and 58 µg kg−1) where the bait was applied after flowering at eight times the recommended rate. This is probably due to bait lodging in the pea straw rather than from plant uptake of strychnine. The study has shown potential plant uptake of strychnine, but at the recommended rate of application under field conditions (3 baits m−2) it is unlikely that strychnine concentrations in the crops studied will exceed the detection limits (10–50 µg kg−1). Nevertheless, the existing programs monitoring strychnine levels in crops treated with baits should be maintained.
Hazards to Wildlife from Soil‐Borne Cadmium Reconsidered
Authors: Beyer W. Nelson 
Published: July 2010

AbstractCadmium is a toxic element that should be included in environmental risk assessments of contaminated soils. This paper argues, however, that hazards to wildlife from cadmium have often been overstated. The literature contains only meager evidence that wild animals have been seriously harmed by cadmium, even at severely contaminated sites. Although some researchers have reported that wildlife have accumulated concentrations of cadmium in their kidneys that were above suggested injury thresholds, the thresholds may be disputed, since they were well below the World Health Organization criterion of 200 mg/kg (wet weight) of cadmium in the renal cortex for protecting human health. Recent risk assessments have concluded that soil cadmium concentrations less than 1 mg/kg are toxic to soil organisms and wildlife, which implies that background concentrations of cadmium naturally found in soils are hazardous. An examination of the databases used to support these assessments suggested that the toxicity of cadmium has been exaggerated.
Temporal Stability of Spatial Patterns of Nitrous Oxide Fluxes from Sloping Grassland
Authors: Velthof G. L. , van Groenigen J. W. , Gebauer G. , Pietrzak S. , Jarvis S. C. , Pinto M. , Corré W. , Oenema O. 
Published: July 2010

AbstractInsight into the temporal and spatial variability of nitrous oxide (N2O) fluxes from soils is required to set up efficient sampling protocols of N2O fluxes and to set up strategies to reduce N2O fluxes. The aim of the present study was to assess the temporal stability of the spatial pattern of N2O fluxes along a transect (400 m) on a fertilized sloping grassland soil. Geostatistical analyses of flux chamber measurements over 4 d showed a clear spatial dependency of N2O fluxes. The spatial variability of N2O fluxes was much higher than the temporal variability during the 4 d. Despite the decreasing magnitude of the fluxes in time, the spatial pattern persisted during 4 d, that is, fluxes were always highest at the steepest part of the transect. The 15N natural abundance (δ15N) in soil N was significantly correlated with N2O fluxes, indicating a long‐term effect of N loss as N2O on the 15N abundance in the soil. It was suggested that topography played a role in the observed spatial patterns of N2O fluxes and Δ15N in soil N. The study showed that despite the persistent spatial pattern of N2O fluxes, flux magnitude may strongly fluctuate in time. Therefore, it is often not possible to combine N2O flux measurements made at different times in order to obtain enough data for geostatistical analysis.
Nitrous Oxide Production from Urea Granules of Different Sizes
Authors: Tenuta Mario , Beauchamp Eric G. 
Published: July 2010

AbstractThree laboratory experiments were conducted to determine if urea granule size or a high concentration of urea prills influence N2O production in soil. Urea hydrolysis results in a localized increase in soil pH and an increase in ammonia concentration. Such conditions may adversely affect the nitrification process, thereby increasing the N2O to NO−3 product ratio. Also, if anaerobic conditions should occur, the N2O to N2 product ratio during denitrification may increase. In general, under aerobic conditions, increasing the urea granule size from a powder to prill (commercial granules) and to larger granules resulted in increased N2O production. The increase in N2O production as granule size increased was accompanied by an increase in NO−2 concentration. The accumulation of NO−2 and the lower rates of disappearance of NH+4, or appearance of NO−3, indicated that the nitrification process was adversely affected. The appearance of N2O was delayed with increasing granule size. A high concentration of urea prills produced a similar but greater effect than large granules. The appearance and rapid production of N2O was closely related to the rapid disappearance of hydroxylamine and the presence of NO−2. The failure to detect hydroxylamine in urea granule‐treated soil may have been due to its rapid oxidation to N2O. The proportion of the added urea N transformed to N2O increased with granule size but did not exceed 1.24% of the urea added. A high concentration of urea prills resulted in 2.80% converted to N2O−N.
Effect of Competing Anions on the Adsorption of Arsenate and Arsenite by Ferrihydrite
Authors: Jain Amita , Loeppert Richard H. 
Published: July 2010

AbstractThe competitive adsorption of arsenate and arsenite and the effect of phosphate and sulfate on adsorption of arsenate and arsenite by ferrihydrite were investigated in the pH range of 3 to 10 and at varying initial ligand concentrations. In dual anion systems, arsenate retention was greater at low pH compared with greater arsenite retention at high pH. In systems with arsenate and arsenite concentrations ≤2.08 molAs kg−1fer each, the effect of arsenate on arsenite sorption was more pronounced than vice versa. On the contrary, at arsenate and arsenite concentrations of 3.47 molAs kg−1fer each, arsenate did not influence arsenite sorption but arsenite substantially reduced arsenate adsorption. The different sorption behavior of arsenite at low and high arsenite concentrations might be due to surface polymerization of adsorbed arsenite at high concentrations. The presence of phosphate resulted in a significant reduction in arsenate and arsenite adsorption by ferrihydrite, with strong dependence on pH and phosphate concentration. The effect of phosphate on arsenate adsorption was greater at high pH than at low pH, whereas the opposite trend was observed for arsenite. Results indicated that arsenate and phosphate compete for the same surface sites, with a moderate preference for arsenate adsorption. There was evidence of the presence of some surface sites that exhibited much higher affinity for arsenite than phosphate. The presence of sulfate did not influence arsenate adsorption but resulted in a considerable reduction in arsenite adsorption below pH 7.0, with the largest reduction at the lowest pH.
Operationally Defined Metal Fractions in Road Deposited Sediment, Honolulu, Hawaii
Authors: Sutherland R. A. , Tack F. M. G. , Tolosa C. A. , Verloo M. G. 
Published: July 2010

AbstractRoad deposited sediments (RDSs) in urban watersheds represent key storage areas for potentially contaminated materials and they are also the primary source of nonpoint pollutants entering aquatic systems. In addition to their association with degradation of stormwater quality, exposure to contaminated RDS has also been implicated in a variety of health issues, particularly among children. Limited data are available to characterize the geochemical properties of RDSs, specifically the association of metals with operationally defined solid fractions. To address this a new optimized four‐step (acid extractable [AEx], reducible, oxidizable, and residual) sequential extraction procedure was applied to 13 road sediments from an urban watershed in Oahu, Hawaii. Eight elements were examined (Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn) in the <2‐mm fraction. Data indicate that more than 50% of Al, Co, Fe, Mn, and Ni was associated with the residual fraction and reflects lithogenic‐pedogenic control. Of the three remaining trace metals that are considered to be anthropogenically enhanced, Cu was dominantly associated with the residual fraction (45%), followed by the oxidizable fraction (26%). Lead was primarily associated with the reducible fraction with a mean of 71%, a value among the highest so far reported in the literature. Zinc had only one‐fifth of its total concentration in the residual fraction, but one‐third in the most mobile and/or bioavailable fraction (AEx), which is susceptible to release into solution with decreases in pH.
Nitrogen‐15 and Bromide Tracers of Nitrogen Fertilizer Movement in Irrigated Wheat Production
Authors: Ottman M. J. , Tickes B. R. , Husman S. H. 
Published: July 2010

AbstractIn irrigated agricultural systems, NO3 leaching is believed to result from high fertilizer rates combined with the need to periodically leach salts from surface soil horizons. The purpose of this research is to estimate N fertilizer movement in the soil of commercial fields of flood‐irrigated wheat (Triticum spp.) while documenting best management practices (BMPs). Potassium bromide and 15N labeled ammonium sulfate were applied as tracers of N fertilizer movement to 1‐ × 1‐m microplots replicated 9 or 10 times in three commercial fields of flood‐irrigated wheat. The soil was sampled at harvest to a depth of 2.4 to 4.0 m. More fertilizer was applied at two out of three sites and more irrigation water was applied at all sites than recommended by BMPs. Bromide recovery in the soil and plant tissue at harvest was 29, 68, and 61% of that applied at the three sites. Most of the 15N measured in the soil profile was contained in the 0‐ to 0.3‐m increment of soil. Recovery on 15N in the soil and plant tissue at harvest was 54, 54, and 69% of that applied. The Br recovery data suggests that 32 ± 28% (standard deviation) of the 15N applied may have leached. The highest leaching potential was measured at the site that adhered to BMPs for N fertilizer management but had the most permeable soil. Nitrate leaching in flood‐irrigated wheat production seems inevitable even if BMPs for N fertilizer management are followed.
Soil Test Phosphorus and Clay Content Effects on Runoff Water Quality
Authors: Cox F. R. , Hendricks S. E. 
Published: July 2010

AbstractDissolved phosphorus (P) in runoff increases with an increase in soil test P, but slopes found for this relationship vary by an order of magnitude. A difference in clay content contributes to this variation. Experiments were conducted on Ultisols of 5 and 32% clay by incorporating poultry (Gallus gallus domesticus) litter and triple superphosphate (TSP) to create a wide range in Mehlich 3‐extractable phosphorus (M3P). Mehlich 3 P increased similarly for the two sources with rate of P applied, but the increase was greater as clay content decreased. Total P in runoff was measured and it was related primarily to the quantity of sediment. Dissolved P (mg L−1) was measured with simulated rainfall and it increased with an increase in M3P (mg dm−3 in the surface 15–20 cm of soil). The slope of dissolved P versus M3P was 0.0040 for the 5% clay soil and 0.0014 for the 32% clay soil. With these relationships, M3P would need to be 250 mg dm−3 at 5% clay and 714 mg dm−3 at 32% clay to result in 1.0 mg L−1 dissolved P in runoff. Dissolved P in samples of runoff collected from natural rainfall with automatic samplers was substantially less than that with simulated rainfall. Thus, there was a marked difference due to method of measurement as well as the difference noted due to day content. Both factors should be considered if attempting to predict the level of dissolved P in runoff from soil test data.
Modifications of Soil Microbial Activity and Triticonazole Biodegradation by Pesticide Formulation Additives
Authors: Charnay Marie‐Paule , Tarabelli Laetitia , Beigel Claude , Barriuso Enrique 
Published: July 2010

AbstractPesticide seed coating represents an example where formulating agents can modify pesticide fate because they are jointly applied in the coating. The influence of additives used to formniate commercial pesticides on degradation in soil of triticonazole [5‐((4‐chlorophenyl) methylene)‐2,2‐dimethyl‐1‐(1H‐1,2,4‐1riazole‐1‐ylmethyl)cyclopentanol] was considered. The studied additives were three different surfactants, one antifoam, one polymer adhesive, and one solvent. Two doses of some formulating additives commonly included in the commercial formulations were used. The individual effects on overall microbial activity and on triticonazole degradation were monitored during laboratory incubations. Total microbial activity was monitored by respirometric measurements and total soil microbial biomass was determined by fumigation‐extraction. The 14C‐triticonazole behavior was characterized by extraction and monitoring of mineralization kinetics. Only the solvent (propylene glycol) and the nonionic micellar surfactant significantly increased the quantities of organic C mineralized. Triticonazole degradation was modified only after the incorporation of formulation additives at high doses (equivalent to 1 g C additive kg−1 soil). The triticonazole degradation increased with the level of available organic C in the case of the solvent, arguing for degradation by a cometabolic pathway. Degradation decreased with the incorporation of the antifoam and the nonionic and anionic (sodiumalkylnaphthalensulfate) surfactants. High concentrations of formulation additives can modify triticonazole behavior in soils, but at the low levels (equivalent to 0.5 g C additive kg−1 soil), degradation data of triticonazole as an active ingredient alone can be used to describe formulated triticonazole behavior.
Predicting Volatile Organic Vapor Sorption from Soil Specific Surface Area and Texture
Authors: Poulsen Tjalfe G. , Yamaguchi Toshiko , Moldrup Per , de Jonge Lis W. , Rolston Dennis E. 
Published: July 2010

AbstractVapor sorption of a volatile organic chemical (VOC) to soil minerals at low water contents can increase the total VOC sorption capacity of the soil by several orders of magnitude. Vapor sorption can subsequently cause high VOC fluxes out of the soil during periods with fluctuating low soil water contents. Models for predicting VOC sorption, including vapor sorption, as a function of soil water content are therefore valuable for evaluating contaminant volatilization and exposure risk at polluted sites. A model for estimating trichloroethylene (TCE) surption parameters at low relative vapor pressure from ethylene glycol monoethyl ether (EGME)‐measured soil specific surface area (SA) and soil clay and organic carbon content was developed based on TCE sorption data from 26 different porous media. Significant improvement in prediction accuracy compared with a previous model was achieved. Based on data for 13 soils, an organic carbon partitioning coefficient of Koc, = 0.60 foc cm3 g−1 (R2 = 0.97) for TCE is recommended for use in the new TCE sorption model. In case SA is not available, an expression for predicting SA from soil clay content is proposed. The clay‐based TCE surption model was tested against independent data for two Japanese soils (a sand and a clay loam) measured in this study by a gas chromatography‐based soil microcolumn method. The sorption model accurately predicted TCE retardation (sorption) as a function of soil water content for both soils. Model calibration to sorption data for three different VOC's (benzene, TCE, and toluene) implies that the sorption model may also be applied to chemicals other than TCE. However, sorption measurements for more chemicals and soils at varying water contents are necessary to further generalize the VOC sorption model.
Leaching Rates and Preferential Flow of Selected Herbicides through Tilled and Untilled Soil
Authors: Elliott Jane A. , Cessna Allan J. , Nicholaichuk Wally , Tollefson Laurie C. 
Published: July 2010

AbstractPesticides can be transported to ground water more rapidly through preferential flowpaths than would be predicted from their physico‐chemical properties. The leaching rates of the herbicides 2,4‐D, bromoxynil, clopyralid, dicamba, diclofop, MCPA, and mecoprop were compared in this study on plots filled after harvest (conventional till, CT) and those that were not (fall tillage operation omitted, NT). The soil‐incorporated herbicides triallate and trifluralin were applied to the CT plot only. Herbicide was applied immediately prior to a leaching irrigation for salt removal, which represents a “worst‐case” scenario for pesticide leaching. Direct evidence of preferential flow was obtained when the herbicides, with the exception of triallate and trifluralin, were detected in the first water reaching the tile drains. Although the nonincorporated herbicides were transported preferentially at the same rate, the amounts transported depended on the solubility and adsorption coefficient (Koc) of the herbicide. Only 0.01% of the application of the least soluble herbicide, diclofop, was transported, compared with 0.46% of the most soluble herbicide, dicamba. Preferential flow was only slightly reduced by the tillage pass. The amounts of herbicide transported to the tile drain, however, were substantially reduced on the CT plot. The tillage effect was greatest for the more soluble and less strongly absorbed herbicides. There was no clear relationship between amounts transported in the year after application and reported persistence but herbicides with the longer half‐lives persisted in relatively greater amounts than the other herbicides.
Long‐Term Wastewater Treatment Effectiveness of a Northern Wisconsin Peatland
Authors: Nichols Dale S. , Higgins Dale A. 
Published: July 2010

AbstractSecondary effluent from the Drummond, WI wastewater stabilization lagoon system was applied to an acidic, nutrient‐poor, 8.3‐ha peatland for the purpose of advanced wastewater treatment. Application occurred from June through October at an average rate of 10 cm yr−1 from 1979 to 1982, 24 cm yr−1 from 1983 to 1988, and 40 cm yr−1 from 1989 to 1996, increasing surface flow from the application area by 47, 78, and 154%, respectively. The pH of the peatland outflow increased from 4.2 to 6.7, chloride rose from 1.1 mg L−1 to 80 mg L−1, and total phosphorus increased from 0.05 mg L−1 to 0.6 mg L−1. Because raw sewage input was only one‐half of the lagoon system's design capacity, the lagoons provided a high degree of sewage treatment, removing 95% of suspended solids (SS), biochemical oxygen demand (BOD), and nitrogen from the wastewater stream. Phosphorus removal in the lagoons, which was 98% in the first years of operation, declined to 85% by 1995. The peatland contributed little additional treatment, removing only 37% of the nitrogen and 17% of the phosphorus remaining in the lagoon effluent. The peatland's capacity to retain phosphorus was exhausted after a few years of application. Increased pH, nutrient availability, and water levels altered the peatland vegetation community. The Sphagnum ground cover was reduced or eliminated in many places, and dense stands of cattail (Typha sp.) developed in some areas. Small peatlands such as this one seem poor candidates for use as tertiary treatment systems.