bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of Sorption and Biodegradation of Parathion and Its Metabolite Paraoxon in Soil
Authors: Saffih‐Hdadi K. , Bruckler L. , Barriuso E. 
Published: June 2010

ABSTRACTTo investigate the distribution of parathion [O,O‐diethyl O‐(4‐nitrophenyl) phosphorothioate] and its highly toxic metabolite paraoxon [O,O‐diethyl O‐(4‐nitrophenyl)phosphate] between the soluble and sorbed pools in the soil, batch experiments were conducted to evaluate the rate of adsorption and desorption of 14C‐labeled parathion and paraoxon in soil. The mineralization and degradation of these products were also investigated during a 56‐d experiment under controlled laboratory conditions. Adsorption patterns indicated initial fast adsorption reactions occurring within 4 h for both parathion and paraoxon. We also observed the formation of nonextractable residues. The paraoxon was more intensively degraded than the parathion, and production of p‐nitrophenol and other metabolites was observed. A kinetic model was developed to describe the sorption and biodegradation rates of parathion, taking into account the production, retention, and biodegradation of paraoxon, the main metabolite of parathion. After fitting the parameters of the model we made a simulation of the kinetics of the appearance and disappearance of paraoxon. From the simulation we predicted a quantity of metabolite in the liquid phase amounting to 1% of the quantity of parathion initially applied. This is in agreement with the experimental data.
Targeted Sampling Protocol as Prelude to Bacterial Source Tracking with Enterococcus faecalis
Authors: Kuntz Robin L. , Hartel Peter G. , Godfrey Dominique G. , McDonald Jennifer L. , Gates Keith W. , Segars William I. 
Published: June 2010

ABSTRACTRecent studies suggest that host origin databases for bacterial source tracking (BST) must contain a large number of isolates because bacterial subspecies change with geography and time. A new targeted sampling protocol was developed as a prelude to BST to minimize these changes. The research was conducted on the Sapelo River, a tidal river on the Georgia coast. A general sampling of the river showed fecal enterococcal numbers ranging from <10 (below the limit of detection) to 990 colony‐forming units (CFU) per 100 mL. Locations with high enterococcal numbers were combined with local knowledge to determine targeted sampling sites. Fecal enterococcal numbers around one site ranged from <10 to 24000 CFU per 100 mL. Bacterial source tracking was conducted to determine if a wastewater treatment facility at the site was responsible for this contamination. The fecal indicator bacterium was Enterococcus faecalis Ribotyping, automated with a RiboPrinter (DuPont Qualicon, Wilmington, DE), was the BST method. Thirty‐seven ribotypes were observed among 83 Ent. faecalis isolates obtained from the Sapelo River and the wastewater lagoon. Sixteen ribotypes were associated with either the river or the lagoon, and only five ribotypes (14%) were shared. Nevertheless, these five ribotypes represented 39 of the 83 Ent. faecalis isolates, almost a majority (47%). These results suggest that the fecal contamination in the river came from the wastewater treatment facility. As a prelude to BST, targeted sampling minimized subspecies changes with geography and time, and eliminated the need for a permanent host origin database by restricting BST to a small geographic area and requiring sampling to be completed in one day.
Sorption of Arsenic from Soil‐Washing Leachate by Surfactant‐Modified Zeolite
Authors: Sullivan Enid J. , Bowman Robert S. , Legiec Irene A. 
Published: June 2010

ABSTRACTPost‐treatment of leachate from soil‐washing remedial actions may be necessary depending on the amounts of dissolved contaminants present. Uptake of arsenic species by surfactant‐modified zeolite (SMZ) from a synthetic soil leachate (pH of approximately 12 [NaOH]) was measured as a test of SMZ as a post‐treatment sorbent. Batch sorption isotherms were prepared using leachate to SMZ ratios from 40:1 to 4:1, and temperatures of 25 and 15°C. Equilibrium levels of dissolved and total solution arsenic were similar. At each temperature, sorption appeared to reach a plateau or maximum, then decreased at the highest solution concentration, corresponding to the lowest amount of zeolite added (2.5 g). A maximum sorption value of 72.0 mmol of arsenic per kg of SMZ (5400 mg/kg) was observed at 25°C, and 42.1 mmol/kg (3150 mg/kg) at 15°C. Total arsenic recoveries varied from 74 to 125%. Surfactant‐modified zeolite removed up to 97% of dissolved organic carbon and decolorized the leachate solutions. Excluding the points for the highest arsenic to SMZ ratio, the sorption isotherms were well described by the linearized form of the Langmuir equation, with coefficients of determination greater than 0.90 at both temperatures. Sorption of arsenic by SMZ is attributed to anion exchange with counterions on the surfactant head groups, and/or partitioning of organic carbon–complexed arsenic into the surfactant bilayer.
Redistribution of Slurry Components as Influenced by Injection Method, Soil, and Slurry Properties
Authors: Petersen S⊘ren O. , Nissen Henrik H. , Lund Ivar , Ambus Per 
Published: June 2010

ABSTRACTThe distribution of moisture, degradable C, and N after direct injection of slurry can affect the turnover and plant availability of slurry N. This study examined effects of injection method, soil conditions, and slurry properties on the infiltration of several slurry components under practical conditions. The water retention capacity of 22 pig and cattle slurries was quantified by dialysis at −0.016, −0.047, and −0.100 MPa. All slurries followed the relationship: relative water loss = 1/(1 +aVS[volatile solids]), indicating that retention of liquids in the slurry injection zone can be predicted from slurry VS and soil water potential. Two‐disc injection and harrow tine injection were simulated (no slurry applied) in five trials. Two trials indicated that disc injection resulted in higher permeability compared with harrow tine injection. In a separate experiment, soil moisture and dissolved ions were monitored in and around injection slits amended with pig or cattle slurry. Moisture gradients, which were recorded with small printed‐circuit‐board (PCB) time‐domain‐reflectometry (TDR) probes, were temporally stable and reestablished following rainfall. Slit sections with pig and cattle slurry containing13C‐acetate and15N‐ammonium showed a shift in the13C to15N ratio of the injection zone within 24 h, which was explained by removal of dissolved C and/or retention of NH+4Cattle slurry was more concentrated around the injection slit than pig slurry, and greater contact between slurry and soil was obtained with harrow tine injection. The heterogeneity of slurry C and N distribution after direct injection should be accounted for in models describing slurry N turnover.
Effect of Cry3Bb Transgenic Corn and Tefluthrin on the Soil Microbial Community: Biomass, Activity, and Diversity
Authors: Devare M. H. , Jones C. M. , Thies J. E. 
Published: June 2010

ABSTRACTTransgenic Bt corn expressing the Cry3Bb insecticidal protein active against corn rootworm (CRW) (Diabroticaspp.; Coleoptera: Chrysomelidae) was released for commercial use in 2003 and is expected to be widely adopted. Yet, the direct and indirect risks to soil microorganisms of growing this CRW‐resistant Bt corn versus applying insecticides to control the rootworm have not been assessed under field conditions. The effects of CRW Bt corn and the insecticide tefluthrin [2,3,5,6‐tetrafluoro‐4‐methylbenzyl (Z)‐(1RS)‐cis‐3‐(2‐chloro‐3,3,3‐trifluoroprop‐1‐enyl)‐2,2‐dimethylcyclopropanecarboxylate] on soil microbial biomass, activity (N mineralization potential, short‐term nitrification rate, and soil respiration), and bacterial community structure as determined by terminal restriction fragment length polymorphism (T‐RFLP) analysis were assessed over two seasons in a field experiment. Bt corn had no deleterious effects on microbial activity or bacterial community measures compared with the non‐transgenic isoline. The T‐RFLP analysis indicated that amplifiable bacterial species composition and relative abundance differed substantially between years, but did not differ between rhizosphere and bulk soils. The application of tefluthrin also had no effect on any microbial measure except decreased soil respiration observed in tefluthrin‐treated plots compared with Bt and non‐transgenic isoline (NoBt) plots in 2002. Our results indicate that the release of CRW Bt corn poses little threat to the ecology of the soil microbial community based on parameters measured in this study.
Dissolution of Trace Element Contaminants from Two Coastal Plain Soils as Affected by pH
Authors: Bang JiSu , Hesterberg Dean 
Published: June 2010

ABSTRACTTrace element mobility in soils depends on contaminant concentration, chemical speciation, water movement, and soil matrix properties such as mineralogy, pH, and redox potential. Our objective was to characterize trace element dissolution in response to acidification of soil samples from two abandoned incinerators in the North Carolina Coastal Plain. Trace element concentrations in 11 soil samples from both sites ranged from 2 to 46 mg Cu kg−1, 3 to 105 mg Pb kg−1, 1 to 102 mg Zn kg−1, 3 to 11 mg Cr kg−1, <0.1 to 10 mg As kg−1, and <0.01 to 0.9 mg Cd kg−1 Acidified CaCl2 solutions were passed through soil columns to bring the effluent solution to approximately pH 4 during a 280‐h flow period. Maximum concentrations of dissolved Cu, Pb, and Zn at the lowest pH of an experiment (pH 3.8–4.1) were 0.32 mg Cu L−1, 0.11 mg Pb L−1, and 1.3 mg Zn L−1 for samples from the site with well‐drained soils, and 0.25 mg Cu L−1, 1.2 mg Pb L−1, and 1.4 mg Zn L−1 for samples from the site with more poorly drained soils. Dissolved Cu concentration at pH 4 increased linearly with increasing soil Cu concentration, but no such relationship was found for Zn. Dissolved concentrations of other trace elements were below our analytical detection limits. Synchrotron X‐ray absorption near edge structure (XANES) spectroscopy showed that Cr and As were in their less mobile Cr(III) and As(V) oxidation states. XANES analysis of Cu and Zn on selected samples indicated an association of Cu(II) with soil organic matter and Zn(II) with Al‐ and Fe‐oxides or franklinite.
Assessment of the Use of Industrial By‐Products to Remediate a Copper‐ and Arsenic‐Contaminated Soil
Authors: Lombi Enzo , Hamon Rebecca E. , Wieshammer Gerlinde , McLaughlin Mike J. , McGrath Steve P. 
Published: June 2010

ABSTRACTTwo water treatment sludges (WTS‐A, WTS‐B), two red muds (RM), and red gypsum (RG), all rich in iron oxy‐hydroxides, were added to a soil highly polluted with As and Cu at 2% (w/w) to reduce metal bioavailability. Because the amendments increased soil pH to approximately 6, a lime treatment to the same pH and an unamended treatment were included for comparison. All the amendments had significant positive effects on the soil microbial biomass and growth of ryegrass (Lolium multiflorum Lam. cv. Avance), but only WTS‐A improved lettuce (Lactuca sativa L. cv. Tom Thumb) growth. The mineralization of added ammonium nitrogen was not significantly affected by the treatments, while a physiologically based extraction test (PBET) showed that bioaccessibility of As was low (<5%) and decreased only in the WTS‐A treatment. Concentrations of As in soil pore water and extractable As only decreased in the WTS and RG treatments. In contrast, Cu concentrations in soil pore water and extractable Cu decreased in all treatments, by more than 84% in the WTS, RM, and RG treatments. Non‐isotopically exchangeable As and Cu were present in colloids in the soil pore water. Untreated soil had <4% isotopically exchangeable As and this decreased by approximately 50%, with WTS, RM, and RG. The labile Cu pool represented a large proportion (34%) of the total Cu pool, and the isotopically exchangeable and soluble Cu were strongly correlated with soil pH. Acidification of the treated soils showed that the labile As and Cu both increased in the treated soils compared with untreated soils. The significance of the treatment effects on soil fertility and potential off‐site transport of As and Cu to ground water are discussed.
Field Dissipation of Acetochlor in Two New Zealand Soils at Two Application Rates
Authors: Ma Qingli , Rahman Anis , Holland Patrick T. , James Trevor K. , McNaughton Don E. 
Published: June 2010

ABSTRACTThe persistence of pesticides in soils has both economic and environmental significance and is often used as a key parameter in pesticide risk assessment. Persistence of acetochlor [2′‐ethyl‐6′‐methyl‐N‐(ethoxymethyl)‐2‐chloroacetylanilide] in two New Zealand field soils was measured over two years and the data were used to identify models that adequately describe acetochlor persistence in the field. Acetochlor was sprayed onto six fallow plots (3 × 9 m each) at each site at the recommended rate (2.5 kg a.i. ha−1) and at twice that rate. Acetochlor concentrations were measured in soil cores. Simple first‐order kinetics (Model 1) adequately described acetochlor persistence in Hamilton clay loam soil (Humic Hapludull, Illuvial Spadic) at the high application rate, but overestimated it at the low application rate. A quadratic model (Model 2), a first‐order double‐exponential model (Model 3), a first‐order biphasic model (Model 4), or a two‐compartment model (Model 5) better described acetochlor persistence at the low application rate. The time for 50% (DT50) and 90% (DT90) of initial acetochlor loss was approximately 9 and 56 d, and 18 and 63 d at low and high application rates, respectively. The more complex Models 2 through 5 also better described the biphasic dissipation of acetochlor in Horotiu sandy loam soil (Typic Orthic Allophanic) than Model 1, with Model 1 significantly underestimating acetochlor concentrations on the day of application at both application rates. The DT50and DT90values were 5 and 29 d and 7 and 31 d at low and high application rates, respectively. Overall, application rate significantly affected the DT50and DT90values in the Hamilton soil, but not in the Horotiu soil. Faster acetochlor loss in the Horotiu soil possibly resulted from the higher soil organic carbon content that retained more acetochlor near the soil surface where higher temperature and photolysis accelerated the loss.
Reduction of Nitrate Leaching with Haying or Grazing and Omission of Nitrogen Fertilizer
Authors: Owens L. B. , Bonta J. V. 
Published: June 2010

ABSTRACTIn some high‐fertility, high‐stocking‐density grazing systems, nitrate (NO3) leaching can be great, and ground water NO3–N concentrations can exceed maximum contaminant levels. To reduce high N leaching losses and concentrations, alternative management practices need to be used. At the North Appalachian Experimental Watershed near Coshocton, OH, two management practices were studied with regard to reducing NO3–N concentrations in ground water. This was following a fertilized, rotational grazing management practice from which ground water NO3–N concentrations exceeded maximum contaminant levels. Using four small watersheds (each approximately 1 ha), rotational grazing of a grass forage without N fertilizer being applied and unfertilized grass forage removed as hay were used as alternative management practices to the previous fertilized pastures. Ground water was sampled at spring developments, which drained the watershed areas, over a 7‐yr period. Peak ground water NO3–N concentrations before the 7‐yr study period ranged from 13 to 25.5 mg L−1 Ground water NO3–N concentrations progressively decreased under each watershed and both management practices. Following five years of the alternative management practices, ground water NO3–N concentrations ranged from 2.1 to 3.9 mg L−1 Both grazing and haying, without N fertilizer being applied to the forage, were similarly effective in reducing the NO3–N levels in ground water. This research shows two management practices that can be effective in reducing high NO3–N concentrations resulting from high‐fertility, high‐stocking‐density grazing systems, including an option to continue grazing.
Cation–π Bonding: A New Perspective on the Sorption of Polycyclic Aromatic Hydrocarbons to Mineral Surfaces
Authors: Zhu Dongqiang , Herbert Bruce E. , Schlautman Mark A. , Carraway Elizabeth R. , Hur Jin 
Published: June 2010

ABSTRACTRecent molecular modeling and spectroscopic studies have suggested that relatively strong interactions can occur between aromatic π donors and metal cations in aqueous solutions. The objective of this study was to characterize potential cation–π interactions between π donors and exchangeable cations accumulated at mineral surfaces via both spectroscopic and batch sorption methods. Quadrupolar splitting in deuterium nuclear magnetic resonance (2H NMR) spectroscopy for d2–dichloromethane, d6–benzene, and d8–toluene (C6D5– moiety) in aqueous suspensions of a Na‐saturated reference montmorillonite unambiguously indicated the ordering of solute molecules with respect to the clay surface. The half line broadening (Δν1/2) of 2H NMR of d6–benzene in montmorillonite suspensions showed that soft exchangeable cations generally resulted in more benzene sorption compared with harder cations (e.g., Ag+ > Cs+ > Na+ > Mg2+, Ba2+). In batch sorption experiments, saturating minerals (e.g., porous silica gels, kaolinite, vermiculite, montmorillonite) with a soft transition metal or softer base cations generally increased the polycyclic aromatic hydrocarbon (PAH) sorption relative to harder cations (e.g., Ag+ >> Cs+ > K+ > Na+; Ba2+ > Mg2+). Sorption of phenanthrene to Ag+–saturated montmorillonite was much stronger compared with 1,2,4,5‐tetrachlorobenzene, a coplanar non‐π donor having slightly higher hydrophobicity. In addition, a strong positive correlation was found between the cation‐dependent sorption and surface charge density of the minerals (e.g., vermiculite, montmorillonite >> silica gels, kaolinite). These results, coupled with the observations in 2H NMR experiments with montmorillonite, strongly suggest that cation–π bonding forms between PAHs and exchangeable cations at mineral surfaces and affects PAH sorption to hydrated mineral surfaces.
Factors Controlling Sorption of Prosulfuron by Variable‐Charge Soils and Model Sorbents
Authors: Hyun Seunghun , Lee Linda S. 
Published: June 2010

ABSTRACTProsulfuron [1‐(4‐methoxy‐6‐methyltriazin‐2‐yl)‐3‐[2‐(3,3,3‐trifluoropropyl) phenylsulfonyl]‐urea), a relatively new sulfonylurea herbicide, is a weak acid (pKa 3.76), and therefore, will undergo pH‐dependent speciation and sorption. Understanding prosulfuron sorption in soils is important for predicting its environmental fate. Soil and solution factors controlling sorption were investigated by measuring prosulfuron sorption on five model sorbents (amorphous silica, α‐alumina, CaSWy1 montmorillonite, commercial humic acid, and anion exchange resin) and 10 variable‐charge soils from CaCl2 and Ca(H2PO4)2 solutions as a function of pH and ionic strength. Anion exchange of prosulfuron accounted for up to 82% of overall sorption in the pH range from 3 to 7. The relative importance of anion exchange to prosulfuron sorption was positively correlated to the ratio of anion and cation exchange capacities. Comparison between organic carbon (OC)‐normalized sorption (Koc) versus pH for humic acid and variable‐charge soils show similar trends with sorption decreasing with increasing pH. However, Koc values estimated from variable‐charge soils in the lower pH range where anion exchange has the greatest contribution to sorption was almost one log unit greater than that estimated from humic acid clearly exemplifying the impact of anion exchange. Similarity in Koc–pH curves for humic acid and variable‐charge soils may result from the fact that (i) cation exchange capacity increases with increasing OC content, thus effective anion exchange capacity is reduced; and (ii) the relative contribution of hydrophobic and hydrophilic sorption mechanisms was fairly constant. Given that both hydrophilic and hydrophobic sorption of prosulfuron decrease with increasing pH, addition of fertilizer and lime amendments may enhance the potential for off‐site leaching of recently applied acidic pesticides.
Differences in the Effects of Simulated Sea Aerosol on Water Relations, Salt Content, and Leaf Ultrastructure of Rock‐Rose Plants
Authors: Sánchez‐Blanco M. J. , Rodríguez P. , Olmos E. , Morales M. A. , Torrecillas A. 
Published: June 2010

ABSTRACTWhite‐leaf rock‐rose (Cistus albidusL.) and Montpellier rock‐rose (C. monspeliensisL.) plants were sprayed 2 to 3 min per day over a 7‐d period, in an unheated plastic greenhouse, with different aqueous solutions containing deionized water alone (control); an anionic surfactant (sodium dodecylbenzenesulfonate 82.5%, 50 mg L−1) (S1); a solution simulating the composition of sea aerosol (S2); and a solution simulating sea aerosol with anionic surfactant (S3). White‐leaf rock‐rose was more sensitive to sea aerosol, showing greater leaf damage and markedly decreased growth, and the presence of surfactant enhanced the phytotoxic effect leading to greater increases in mortality. Montpellier rock‐rose did not appear to be more adversely affected when surfactant was used in combination with sea aerosol, and manifested slight or less severe symptoms than white‐leaf rock‐rose. There was a significant increase in leaf turgor potential in the plants treated with both sea aerosol treatments by osmotic adjustment effect. The decrease in photosynthesis level seems to be due to both stomatal and nonstomatal factors. The results of microscopical analysis of Montpellier rock‐rose plants show that sea aerosol treatment caused alterations in the chloroplast structure, reducing the starch grain and swelling the thylakoid membranes. The results of this study indicated that Montpellier rock‐rose was more tolerant to sea aerosol than white‐leaf rock‐rose, showing a lower reduction in plant growth and less leaf damage, probably because of its ability to compartmentalize the toxic ions at the intracellular level.
Surface Runoff Losses of Phosphorus from Virginia Soils Amended with Turkey Manure Using Phytase and High Available Phosphorus Corn Diets
Authors: Penn C. J. , Mullins G. L. , Zelazny L. W. , Warren J. G. , McGrath J. M. 
Published: June 2010

ABSTRACTMany states have passed legislation that regulates agricultural P applications based on soil P levels and crop P uptake in an attempt to protect surface waters from nonpoint P inputs. Phytase enzyme and high available phosphorus (HAP) corn supplements to poultry feed are considered potential remedies to this problem because they can reduce total P concentrations in manure. However, less is known about their water solubility of P and potential nonpoint‐source P losses when land‐applied. This study was conducted to determine the effects of phytase enzyme and HAP corn supplemented diets on runoff P concentrations from pasture soils receiving surface applications of turkey manure. Manure from five poultry diets consisting of various combinations of phytase enzyme, HAP corn, and normal phytic acid (NPA) corn were surface‐applied at 60 kg P ha−1to runoff boxes containing tall fescue (Festuca arundinaceaSchreb.) and placed under a rainfall simulator for runoff collection. The alternative diets caused a decrease in manure total P and water soluble phosphorus (WSP) compared with the standard diet. Runoff dissolved reactive phosphorus (DRP) concentrations were significantly higher from HAP manure‐amended soils while DRP losses from other manure treatments were not significantly different from each other. The DRP concentrations in runoff were not directly related to manure WSP. Instead, because the mass of manure applied varied for each treatment causing different amounts of manure particles lost in runoff, the runoff DRP concentrations were influenced by a combination of runoff sediment concentrations and manure WSP.