bluuebunny/crossref_metadata_2025_split huggingface dataset:
Virus Retention and Transport as Influenced by Different Forms of Soil Organic Matter
Authors: Zhuang Jie , Jin Yan 
Published: August 2012

ABSTRACTOrganic materials are widespread in natural soil and aquatic environments. Their effect on virus transport is very important in assessing the risk for contamination of ground water by viruses. This study aimed to determine how different forms (mineral‐associated and dissolved) of natural organic matter influence the retention and transport of two bacteriophages (MS‐2 and φX174) in two porous media (a sand and a soil). We found that mineral‐associated organic matter significantly promoted the transport of one virus (MS‐2) but not the other (φX174) in a phosphate‐buffered saline solution. Similarly, MS‐2 was retained less in sand columns with increasing concentrations of dissolved humic acid, while little effect was observed for φX174 under the same conditions. The two viruses have different surface properties and thus exhibited different reactivity to the metal oxides present on sand particles and were affected differently by organic matter. Because the organic matter used in the study was negatively charged and hydrophilic, blocking of virus sorption sites and increasing of virus–medium electrostatic repulsion arising from modification of the sand and virus surface by organic matter are probably responsible for the facilitated transport. For dissolved humic acid, its competition for sorption sites with viruses was an additional mechanism involved. This study suggests that the effect of organic matter varied depending on the organic material properties and the type of viruses involved. As a general trend, the effect of organic matter was dominated by electrostatic rather than hydrophobic interactions.
Root Growth and Metal Uptake in Four Grasses Grown on Zinc‐Contaminated Soils
Authors: Palazzo Antonio J. , Cary Timothy J. , Hardy Susan E. , Lee C. Richard 
Published: August 2012

ABSTRACTDepth and area of rooting are important to long‐term survival of plants on metal‐contaminated, steep‐slope soils. We evaluated shoot and root growth and metal uptake of four cool‐season grasses grown on a high‐Zn soil in a greenhouse. A mixture of biosolids, fly ash, and burnt lime was placed either directly over a Zn‐contaminated soil or over a clean, fine‐grained topsoil and then the Zn‐contaminated soil; the control was the clean topsoil. The grasses were ‘Reliant’ hard fescue (Festuca brevipila R. Tracey), ‘Oahe’ intermediate wheatgrass [Elytrigia intermedia (Host) Nevski subsp. intermedia], ‘Ruebens’ Canada bluegrass (Poa compressa L.), and ‘K‐31’ tall fescue (Festuca arundinacea Schreb.). Root growth in the clean soil and biosolids corresponded to the characteristic rooting ability of each species, while rooting into the Zn‐contaminated soil was related to the species' tolerance to Zn. While wheatgrass and tall fescue had the strongest root growth in the surface layers (0–5 cm) of clean soil or biosolids, wheatgrass roots were at least two times more dense than those of the other grasses in the second layer (5–27 cm) of Zn‐contaminated soil. When grown over Zn‐contaminated soil in the second layer, hard fescue (with 422 mg/kg Zn) was the only species not to have phytotoxic levels of Zn in shoots; tall fescue had the highest Zn uptake (1553 mg/kg). Thus, the best long‐term survivors in high‐Zn soils should be wheatgrass, due to its ability to root deeply into Zn‐contaminated soils, and hard fescue, with its ability to effectively exclude toxic Zn uptake.
Herbicide Loading to Shallow Ground Water beneath Nebraska's Management Systems Evaluation Area
Authors: Spalding Roy F. , Watts Darrell G. , Snow Daniel D. , Cassada David A. , Exner Mary E. , Schepers James S. 
Published: August 2012

ABSTRACTBetter management practices can counter deterioration of ground water quality. From 1991 through 1996 the influence of improved irrigation practices on ground water pesticide contamination was assessed at the Nebraska Management Systems Evaluation Area. Three 13.4‐ha corn (Zea mays L.) fields were studied: a conventional furrow‐irrigated field, a surge‐irrigated field and a center pivot–irrigated field, and a center pivot–irrigated alfalfa (Medicago sativa L.) field. The corn fields received one identical banded application of Bicep (atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4,‐diamine] + metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl)acetamide]) annually; the alfalfa field was untreated. Ground water samples were collected three times annually from 16 depths of 31 multilevel samplers. Six years of sample data indicated that a greater than 50% reduction in irrigation water on the corn management fields lowered average atrazine concentrations in the upper 1.5 m of the aquifer downgradient of the corn fields from approximately 5.5 to <0.5 μg L−1 Increases in deethylatrazine (DEA; 2‐chloro‐4‐amino‐6‐isopropylamino‐s‐triazine) to atrazine molar ratios indicated that reducing water applications enhanced microbial degradation of atrazine in soil zones. The occurrence of peak herbicide loading in ground water was unpredictable but usually was associated with heavy precipitation within days of herbicide application. Focused recharge of storm runoff that ponded in the surge‐irrigated field drainage ditch, in the upgradient road ditch, and at the downgradient end of the conventionally irrigated field was a major mechanism for vertical transport. Sprinkler irrigation technology limited areas for focused recharge and promoted significantly more soil microbial degradation of atrazine than furrow irrigation techniques and, thereby, improved ground water quality.
Adsorption and Transport of Arsenic(V) in Experimental Subsurface Systems
Authors: Williams L. Elizabeth , Barnett Mark O. , Kramer Timothy A. , Melville Joel G. 
Published: August 2012

ABSTRACTThe adsorption and transport of As(V) in a heterogeneous, iron oxide–containing soil was investigated in batch and column laboratory experiments. The As(V) adsorbed rapidly to the soil over the first 48 h, but continued to adsorb slowly over the next several weeks, clearly indicating the potential for rate‐limited transport. The equilibrium As(V) adsorption isotherm was markedly nonlinear, further indicating the potential for nonideal transport. A model developed for the adsorption of As(V) to hydrous ferric oxide (HFO) was able to predict the pH‐dependent adsorption of As(V) to the soil in batch experiments within 0.116 to 0.726 root mean square error (RMSE). Arsenic(V) was significantly retarded in column transport experiments. The column transport experiments were modeled using the one‐dimensional advection–dispersion equation, considering both linear and nonlinear adsorption equilibrium. Although the nonlinear local equilibrium model (NLLE, RMSE = 0.273) predicted the data better than the linear local equilibrium model (LLE, RMSE = 0.317), As(V) breakthrough occurred more rapidly than predicted by either model due to adsorption nonequilibrium. However, due to the presence of an irreversible or slowly desorbing fraction, the peak aqueous As(V) concentration (0.624 mg L−1) and the total amount of As(V) recovered (44%) was lower than predicted based on the two equilibrium models (NLLE and LLE). For the conditions used in this study [1 mg L−1 As(V), pH 4.5 and 9, 0–0.25 mM PO4, 0.53–1.6 cm min−1 pore water velocity], the effect on As(V) mobility and recovery increased in the order pH < pore water velocity < PO4
Partitioning and Availability of Uranium and Nickel in Contaminated Riparian Sediments
Authors: Sowder Andrew G. , Bertsch Paul M. , Morris Pamela J. 
Published: August 2012

ABSTRACTThe effects of iron oxides and organic matter on the partitioning and chemical lability of U and Ni were examined for contaminated riparian sediments from the U.S. Department of Energy's Savannah River Site. In sequential extractions of four sediments that ranged from 12.7 to 82.2 g kg−1 in organic carbon, U was found almost exclusively in moderately labile fractions (93% in acid‐soluble + organically bound). Nickel was distributed across all operationally defined fractions, including substantial amounts in the very labile fractions (4–15% in water‐soluble + exchangeable), noncrystalline and crystalline iron oxides (38–49%), and in the nonlabile residual fraction (25–34%). Aqueous U concentrations in 1:1 sediment–water extracts were highly correlated to dissolved organic carbon (DOC) (R2 = 0.96; p < 0.0001) and ranged from 29 to 410 μg L−1 Aqueous concentrations of Ni exceeded U by two to three orders of magnitude (124–2227 μg L−1) but were not correlated with DOC (R2 = 0.04; p = 0.53). Partitioning and solubility trends suggest that Ni availability is controlled primarily by iron‐oxide phases, whereas U availability is dominated by naturally occurring organic carbon. Discrete mineral phases were also identified as nonlabile reservoirs of anthropogenic metals. In spite of comparably high sediment concentrations, Ni appears to be significantly more available than U in riparian sediments and therefore warrants greater consideration in terms of environmental consequences (i.e., transport, biological uptake, and toxicity).
Characterization of Lead Removal from Contaminated Soils by Nontoxic Soil‐Washing Agents
Authors: Neilson Julia W. , Artiola Janick F. , Maier Raina M. 
Published: August 2012

ABSTRACTFew effective strategies exist for remediating and restoring metal‐contaminated soils. We have evaluated the potential of two environmentally compatible, nondestructive, biological soil‐washing agents for remediating aged, lead‐contaminated soils. Two contaminated soils were washed with 10 mM rhamnolipid biosurfactant and 5.3% carboxymethyl‐β‐cyclodextrin (CMCD). The metal removal efficiency of these agents was compared with 10 mM diethylenetriamine pentaacetic acid (DTPA) and 10 mM KNO3 Lead removal rates by both soil‐washing agents exceeded the removal by KNO3, but were an order of magnitude less than removal by the synthetic chelator, DTPA. Analysis of soil extractions revealed that the Pb in the first soil (3780 mg kg−1) was primarily associated with the soluble, exchangeable, oxide, and residual fractions while the Pb in the second soil (23 900 mg kg−1) was found in the soluble, exchangeable, carbonate, and residual fractions. After 10 consecutive washes, rhamnolipid had removed 14.2 and 15.3% of the Pb from the first and second soils, respectively, and CMCD had removed 5 and 13.4% from the same two soils. The Pb removal rate by both agents either increased or was consistent throughout the 10 extractions, indicating a potential for continued removal with extended washing. Significant levels of Cu and Zn in both soils did not prevent Pb removal by either agent. Interestingly, the effectiveness of each agent varied as a function of Pb speciation in the soil. Rhamnolipid was more effective than CMCD in removing Pb bound to amorphous iron oxides, while both agents demonstrated similar potential for removing soluble, exchangeable, and carbonate‐bound Pb. Neither agent demonstrated potential for the complete remediation of metal‐contaminated soils.
Surface Runoff Losses of Copper and Zinc in Sandy Soils
Authors: Zhang Mingkui , He Zhenli , Calvert David V. , Stoffella Peter J. , Yang Xiaoe 
Published: August 2012

ABSTRACTIncreased anthropogenic inputs of Cu and Zn in soils have caused considerable concern relative to their effect on water contamination. Copper and Zn contents in surface soil directly influence the movement of Cu and Zn. However, minimal information is available on runoff losses of Cu and Zn in agricultural soils, and soil‐extractable Cu and Zn in relation to runoff water quality. Field experiments were conducted in 2001 to study dissolved Cu and Zn losses in runoff in Florida sandy soils under commercial citrus and vegetable production and the relationship between soil‐extractable Cu and Zn forms and dissolved Cu and Zn concentrations in runoff water. Five extraction methods were compared for extracting soil available Cu and Zn. Concentrations of dissolved Cu and Zn in runoff were measured and runoff discharge was monitored. Mean dissolved Cu in field runoff water was significantly correlated with the extractable Cu obtained only by 0.01 mol L−1 CaCl2, Mehlich 1, or DTPA–TEA methods. Dissolved Zn in runoff water was only significantly correlated with extractable Zn by 0.01 mol L−1 CaCl2 The highest correlations to dissolved Cu in runoff were obtained when soil‐available Cu was extracted by 0.01 mol L−1 CaCl2 The results indicate that 0.01 mol L−1 CaCl2–extractable Cu and Zn are the best soil indexes for predicting readily released Cu and Zn in the sandy soils. Both runoff discharge and 0.01 mol L−1 CaCl2–extractable Cu and Zn levels had significant influences on Cu and Zn loads in surface runoff.
Effectiveness of Grassed Waterways in Reducing Runoff and Sediment Delivery from Agricultural Watersheds
Authors: Fiener P. , Auerswald K. 
Published: August 2012

ABSTRACTGrassed waterways (GWWs) drain surface runoff from fields without gullying along the drainageway. Secondary functions include reducing runoff volume and velocity and retaining sediments and harmful substances from adjacent fields. Grass cover (sward)–damaging sedimentation in the GWW is commonly reduced by frequent mowing, but in doing so the effectiveness of the waterway relative to the secondary functions is reduced. Our objectives were to (i) evaluate whether the maintenance of a GWW can be reduced if on‐site erosion control is effective, (ii) measure the effectiveness of such a GWW, and (iii) analyze the underlying mechanisms. A long‐term (1994–2000) landscape experiment was performed in four watersheds, where two had GWWs for which maintenance was largely neglected. An intensive soil conservation system was established on all fields. Runoff and sediment delivery were continuously measured in the two watersheds with GWWs and in their paired watersheds that were similar, but without GWWs. Runoff was reduced by 90 and 10% for the two sets of paired watersheds, respectively. The different efficiencies of the GWWs resulted from different layouts (doubled width and flat‐bottomed vs. v‐shaped drainageway). The GWWs reduced sediment delivery by 97 and 77%, respectively, but the sward was not damaged by sedimentation. Grain sizes > 50 μm were settled due to gravity in both GWWs. Smaller grain sizes were primarily settled due to infiltration, which increased with a more effective runoff reduction. In general, the results indicated a high potential of GWWs for reducing runoff volume and velocity, sediments, and agrochemicals coming from agricultural watersheds.
Soil Sorption of Acidic Pesticides
Authors: Spadotto Claudio A. , Hornsby Arthur G. 
Published: August 2012

ABSTRACTA model of acidic pesticide sorption in soils was developed from theoretical modeling and experimental data, which initially considered a combination of a strongly acidic pesticide and a variable‐charge soil with high clay content. Contribution of 2,4‐D [(2,4‐dichlorophenoxy) acetic acid] anionic‐form sorption was small when compared with molecular sorption. Dissociation of 2,4‐D was not sufficient to explain the variation in Kd as a function of pH. Accessibility of soil organic functional groups able to interact with the pesticide (conformational changes) as a function of organic matter dissociation was proposed to explain the observed differences in sorption. Experimental 2,4‐D sorption data and Koc values from literature for flumetsulam [N‐(2,6‐difluorophenyl)‐5‐methyl [1,2,4] triazolo [1,5‐a] pyrimidine‐2‐sulfonamide] and sulfentrazone [N‐[2,4‐dichloro‐5‐[4‐(difluromethyl)‐4,5‐dihydro‐3‐methyl‐5‐oxo‐1H‐1,2,4‐triazol‐1‐y1] phenyl] methanesulfonamide] in several soils fit the model.
Stochastical Analysis of Surfactant‐Enhanced Remediation of Denser‐than‐Water Nonaqueous Phase Liquid (DNAPL)–Contaminated Soils
Authors: Zhang Renduo , Wood A. Lynn , Enfield Carl G. , Jeong Seung‐Woo 
Published: August 2012

ABSTRACTStochastical analysis was performed to assess the effect of soil spatial variability and heterogeneity on the recovery of denser‐than‐water nonaqueous phase liquids (DNAPL) during the process of surfactant‐enhanced remediation. UTCHEM, a three‐dimensional, multicomponent, multiphase, compositional model, was used to simulate water flow and chemical transport processes in heterogeneous soils. Soil spatial variability and heterogeneity were accounted for by considering the soil permeability as a spatial random variable and a geostatistical method was used to generate random distributions of the permeability. The randomly generated permeability fields were incorporated into UTCHEM to simulate DNAPL transport in heterogeneous media and stochastical analysis was conducted based on the simulated results. From the analysis, an exponential relationship between average DNAPL recovery and soil heterogeneity (defined as the standard deviation of log of permeability) was established with a coefficient of determination (r2) of 0.991, which indicated that DNAPL recovery decreased exponentially with increasing soil heterogeneity. Temporal and spatial distributions of relative saturations in the water phase, DNAPL, and microemulsion in heterogeneous soils were compared with those in homogeneous soils and related to soil heterogeneity. Cleanup time and uncertainty to determine DNAPL distributions in heterogeneous soils were also quantified. The study would provide useful information to design strategies for the characterization and remediation of nonaqueous phase liquid–contaminated soils with spatial variability and heterogeneity.
Simplified Method for Detecting Tritium Contamination in Plants and Soil
Authors: Andraski B. J. , Sandstrom M. W. , Michel R. L. , Radyk J. C. , Stonestrom D. A. , Johnson M. J. , Mayers C. J. 
Published: August 2012

ABSTRACTCost‐effective methods are needed to identify the presence and distribution of tritium near radioactive waste disposal and other contaminated sites. The objectives of this study were to (i) develop a simplified sample preparation method for determining tritium contamination in plants and (ii) determine if plant data could be used as an indicator of soil contamination. The method entailed collection and solar distillation of plant water from foliage, followed by filtration and adsorption of scintillation‐interfering constituents on a graphite‐based solid phase extraction (SPE) column. The method was evaluated using samples of creosote bush [Larrea tridentata (Sessé & Moc. ex DC.) Coville], an evergreen shrub, near a radioactive disposal area in the Mojave Desert. Laboratory tests showed that a 2‐g SPE column was necessary and sufficient for accurate determination of known tritium concentrations in plant water. Comparisons of tritium concentrations in plant water determined with the solar distillation–SPE method and the standard (and more laborious) toluene‐extraction method showed no significant difference between methods. Tritium concentrations in plant water and in water vapor of root‐zone soil also showed no significant difference between methods. Thus, the solar distillation–SPE method provides a simple and cost‐effective way to identify plant and soil contamination. The method is of sufficient accuracy to facilitate collection of plume‐scale data and optimize placement of more sophisticated (and costly) monitoring equipment at contaminated sites. Although work to date has focused on one desert plant, the approach may be transferable to other species and environments after site‐specific experiments.
Reactions of Mid‐Southern U.S. Soybean Cultivars to Bean Pod Mottle Virus and Tobacco Ringspot Virus
Authors: Shakiba Ehsan , Chen Pengyin , Gergerich Rose , Li Shuxian , Dombek Donald , Shi Ainong , Brye Kristofor 
Published: August 2012

ABSTRACTBean pod mottle virus (BPMV) and Tobacco ringspot virus (TRSV) are two important viral pathogens causing reduction of seed yield and quality in soybean [Glycine max (L.) Merr.]. Various BPMV and TRSV isolates have been observed, but no host resistance has been reported. The objective of this study was to screen a set of modern soybean cultivars for resistance or tolerance to BPMV and TRSV. A total of 303 cultivars currently grown in the mid‐southern United States were screened in the greenhouse for their reactions to BPMV and TRSV. Each cultivar was inoculated with a mild and a virulent isolate of each virus. None of the cultivars tested was resistant to BPMV, but a range of tolerance to this virus was observed among the cultivars. An enzyme‐linked immunosorbent assay (ELISA) confirmed the presence of BPMV in the high and low tolerance cultivars. Tolerance to BPMV is associated with less of a reduction in plant height and biomass on infected plants. Cultivars were classified into four groups, high, moderate, low, and very low tolerance, on the basis of their having exhibited ≤20, 21 to 40, 41 to 60, or >60% of a reduction in plant height and ≤25, 26 to 50, 51 to 75, and >75% plant biomass reduction, respectively. None of the cultivars was resistant to TRSV, and all showed bud blight symptoms by 10 d after inoculation. However, 55 cultivars recovered 5 wk after inoculation, with more than 80% of the plants growing out of the bud blight symptoms and forming new leaves. The recovered plants, although systemically infected, clearly showed tolerance to TRSV at a later stage. These results may be helpful to soybean producers for selecting tolerant cultivars to grow in areas where BPMV and/or TRSV may cause problems in production.
Reactions of Commercial Soybean Cultivars from the Mid South to Soybean Mosaic Virus
Authors: Shakiba Ehsan , Chen Pengyin , Gergerich Rose , Li Shuxian , Dombek Donald , Brye Kris , Shi Ainong 
Published: August 2012

ABSTRACTSoybean mosaic virus (SMV) is one of the most important viral diseases, causing drastic reductions in seed yield and quality. Seven SMV strains, G1 through G7, have been identified, and three resistance loci, Rsv1, Rsv3, and Rsv4, have been reported in the United States. The objectives of this study were to evaluate the reactions of a set of modern soybean [Glycine max (L.) Merr.] cultivars to SMV and to deduce which previously reported genes were involved in resistance. A total of 303 cultivars currently grown in the mid‐southern United States were screened in the greenhouse with six SMV strains (G1, G2, G3, G5, G6, and G7). The results demonstrated that 189 cultivars were susceptible to all six SMV strains. Three cultivars were resistant to G1, G2, G3, G5, and G6 but developed stem‐tip necrosis after infection with G7, so these were presumed to carry the Rsv1 allele. Sixty‐six cultivars were resistant to G1 through G3 but susceptible to G5 through G7 and presumably carry Rsv1‐y. One cultivar was resistant to G1 through G3 but necrotic to G5 through G7 and may carry Rsv1‐k. Two cultivars probably carry Rsv1‐t because they were resistant to G1, G2, G5, and G6 but necrotic to G3 and G7, and another two cultivars may carry Rsv1‐n because they were necrotic to G1, G2, G5, and G6 but susceptible to G2 and G7. Four cultivars were susceptible to G1 through G3 but resistant to G5 through G7, and therefore they may carry Rsv3. Two cultivars were resistant to all six SMV strains, and therefore they may carry Rsv4, Rsv1‐h, or two‐gene combinations. There were 34 cultivars exhibiting unique SMV reaction patterns that may carry novel genes or alleles, including 23 cultivars that may carry novel alleles at the Rsv1 locus and 11 that may carry novel alleles at the Rsv3 locus. The results from this study can be used by breeders to choose resistant cultivars as parents in soybean breeding programs and by producers to select resistant cultivars in areas where SMV is a disease of concern for soybean production.