bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stochastic Simulation of Field‐Scale Pesticide Transport Using Opus and GLEAMS
Authors: Zacharias S. , Heatwole C. D. , Persaud N. , Bruggeman A. C. , Kumar D. , Smith C. N. 
Published: July 2010

AbstractIncorporating variability in soil and chemical properties into root zone leaching models should provide a better representation of pollutant distribution in natural field conditions. Our objective was to determine if a more mechanistic rate‐based model (Opus) would predict soil water and pesticide mass in the soil profile more accurately than a capacity‐based model (GLEAMS) when spatial variability and uncertainly in parameters are considered. Predictions of spatial variations of soil water content and movement of aldicarb [2‐methyl‐2‐(methylthio)‐propionaldehyde O‐(methylcarbamoyl) oxime] and metolachlor [2‐chloro‐N‐(2‐methoxy‐1‐methylethyl) acetamide] in the root zone were compared using 3 yr of observed data from a 3.9‐ha agricultural field in southwest Georgia. Spatial variability of soil physical properties, pesticide properties, and pesticide application were described using probability distributions fitted to measured field data, after removing spatial trends that were physically meaningful. There were significant differences in mean soil water content predicted by the two models, although variations around the mean were comparable. Pesticide mass predictions were different on most post‐application dates in both mean and spatial variation. The less rigorous GLEAMS predicted mean depth‐averaged soil water content and pesticide mass in the 1.2‐m profile at least as good as the more mechanistic Opus, although it did not simulate depth distributions of water or pesticide mass as well as Opus. GLEAMS simulated spatial variations of depth‐averaged soil water content and pesticide mass in the field with reasonable accuracy while employing fewer parameters that exhibit lower spatial variability.
Estimates of Soil Nitrate Distributions Using Cokriging with Pseudo‐Crossvariograms
Authors: Zhang Renduo , Shouse Pete , Yates Scott 
Published: July 2010

AbstractNitrate (NO−3) is one of the major nonpoint source pollutants in the vadose zone. In this study, NO−3 distributions were estimated in an 800 by 800 by 1.8 m soil volume using kriging and cokriging with nonsymmetric pseudo‐crossvariograms. Cokriging with pseudo‐crossvariograms maximized the use of available information at different soil depths. Cokriging allowed easily obtained information at shallow layers to be used to improve soil chemical estimations at deeper layers. Compared with kriging, cokriging significantly reduced the mean squared errors (MSEs) and mean kriging variances (MKVs) of NO−3 estimations in the soil. For the same estimation accuracy of kriging, cokriging with pseudo‐crossvariograms used less than half the data; thus potentially it could reduce more than half the sampling cost than kriging estimation. Cokriging with pseudo‐crossvariograms was shown to be a precise and an economic way for determining nonpoint source pollutant distributions in large fields.
Evaluation of a GIS‐Linked Model of Salt Loading to Groundwater
Authors: Corwin D. L. , Carrillo M. L. K. , Vaughan P. J. , Rhoades J. D. , Cone D. G. 
Published: July 2010

AbstractThe ability to assess through prognostication the impact of nonpoint source (NPS) pollutant loads to groundwater, such as salt loading, is a key element in agriculture's sustainability by mitigating deleterious environmental impacts before they occur. The modeling of NPS pollutants in the vadose zone is well suited to the integration of a geographic information system (GIS) because of the spatial nature of NPS pollutants. The GIS‐linked, functional model TETrans was evaluated for its ability to predict salt loading to groundwater in a 2396 ha study area of the Broadview Water District located on the westside of central California's San Joaquin Valley. Model input data were obtained from spatially‐referenced measurements as opposed to previous NPS pollution modeling effort's reliance upon generalized information from existing spatial databases (e.g., soil surveys) and transfer functions. The simulated temporal and spatial changes in the loading of salts to drainage waters for the study period 1991–1996 were compared to measured data. A comparison of the predicted and measured cumulative salt loads in drainage waters for individual drainage sumps showed acceptable agreement for management applications. An evaluation of the results indicated the practicality and utility of applying a one‐dimensional, GIS‐linked model of solute transport in the vadose zone to predict and visually display salt loading over thousands of hectares. The display maps provide a visual tool for assessing the potential impact of salinity upon groundwater, thereby providing information to make management decisions for the purpose of minimizing environmental impacts without compromising future agricultural productivity.
Hydrologic Response: Kaho'olawe, Hawaii
Authors: Wahlstrom Erik , Loague Keith , Kyriakidis Phaedon C. 
Published: July 2010

AbstractKaho'olawe, the eighth largest island in the Hawaiian chain, has experienced major surface erosion during the last century due to overgrazing and military activity. In this paper we report the results from a series of physically‐based numerical simulations of hydrologic response, to large rainfall events, that were performed for Kaho'olawe. An event‐based rainfall‐runoff and erosion model (i.e., KINEROS) was applied, in a geographic information system (GIS) framework, to make quantitative and distributed estimates of infiltration, Horton overland flow generation, and erosion. A digital elevation model (DEM) was employed to delineate individual catchments across the island, and define areas of uniform slope within each catchment. A Landsat MSS scene of Kaho'olawe was used to classify the island into three distinct landcover categories via the normalized difference vegetation index (NDVI). The landcover categories were then used to further approximate the spatial pattern of near‐surface soil hydraulic properties across the island. Distributed estimates of saturated hydraulic conductivity and sorptivity were obtained by ordinary kriging of 135 field measurements from the island. Sensitivity analysis was performed to characterize what impact the uncertainty in soil‐hydraulic property and rainfall data had on simulated runoff. Horton overland flow and the related transport limited erosion were shown to be highly variable. The introduction of vegetation to denuded areas on Kaho'olawe was found to significantly reduce erosion.
A Flow‐Through Reactor with an Infinite Sink for Monitoring Desorption Processes
Authors: Freese Dirk , Weidler Peter G. , Grolimund Daniel , Sticher Hans 
Published: July 2010

AbstractThe assessment of elemental release processes in soils are of large interest in soil research. A technique is presented where the advantages of a flow‐through reactor are combined with a specific infinite sink. Between the two reactors an electrolyte solution (pH 6) acting as a transport carrier was circulated continuously in a closed‐loop setup. To demonstrate the capability of the new technique, phosphate desorption kinetics from different synthetic Fe and Mn hydroxides coated on silica sand were studied. The relative amount of P desorbed increased in the order ferrihydrite (10% of the initially sorbed P) < goethite (20%) << hematite (65%) < Mn dioxide (80%). We suggest that this technique can also be adapted to other issues, for example, desorption of other anions and cations from solid phases (soils and sediments) because the composition of the infinite sink is variable.
Evaluation of Flow and Solute Transport Parameters for Heap Leach Recovery Materials
Authors: Decker David L. , Tyler Scott W. 
Published: July 2010

AbstractMining low‐grade precious metals deposits often involves the bulk processing of ore by leaching with cyanide. Once the precious metals concentration in the leachate fluid drops to an economic cutoff point, processing ceases and the mine is required to meet drinking water standards for the latent leachate fluid that continues to drain from the heap. A common closure method is to rinse the heap with relatively clean water until the those requirements are met. However, it has been observed that concentrations of constituents, cyanide in particular, remain elevated at rinse times that exceed those times predicted with a simple advective‐dispersive type of transport model. To quantify the flow and transport behavior of spent heaps, the hydraulic and solute transport characteristics of several heap‐leach materials from northern Nevada have been determined. Data from the U.S. Bureau of Mines laboratory column tracer tests and new data collected from a series of tracer experiments with sodium Br− on heap material collected from the a large‐scale heap in the Cariin Trend, Elko County, Nevada, are presented. A 6‐m scale column incorporating time domain reflectometry was used to investigate the rinsing characteristics of spent heap‐leach material. The breakthrough curve data from these experiments are analyzed using the traditional advection‐dispersion equation and a dual‐porosity model. The dual‐porosity model provided significantly improved fits to the observed data compared with the advection‐dispersion model. Data from the experimental results are used to show optimal rinsing strategies can be developed when heap hydraulic properties are considered.
Leaching Behavior of Chlorinated Hydrocarbon Soil Fumigants in Repacked Soil Columns
Authors: Zebarth B. J. , Szeto S. Y. 
Published: July 2010

AbstractThe leaching behavior of Telone (active ingredients 1,3‐dichloropropene and 1,2‐dichloropropane) and Telone II (active ingredient 1,3‐dichloropropene) and the trace chlorinated hydrocarbon impurities in the fumigant formulations including 1,2,2‐trichloropropane; 1,2,3‐trichloropropane; 2,3‐dichloropropene; and 1,3‐dichloropropane, were studied using 75 cm long repacked soil columns in two experiments. In Exp. 1, soil columns received Telone, Telone II, or no soil fumigant. In Exp. 2, Telone II was applied to soil columns containing four soils: surface or subsurface samples from coarse‐ and medium‐textured soils. The concentrations of the chlorinated hydrocarbon compounds were measured in the soil and leachate. The concentrations of 3‐chloroallyl alcohol and 3‐chloroacrylic acid, breakdown products of 1,3‐dichloropropene, were also measured in leachate after Telone application. 1,3‐Dichloropropene, 3‐chloroallyl alcohol, and 3‐chloroacrylic acid degraded rapidly, and exhibited minimal adsorption to the soil. The remaining compounds were persistent in soil. Recovery of the applied compounds was lower in the surface than in the subsurface soils, particularly in the medium‐textured soil, likely due to greater biological activity in the surface soils. The risk of loss of these compounds from the root zone was minimal for 1,3‐dichloropropene, and lower with use of Telone II than of Telone. 1,2,2‐Trichloropropane was identified as the compound in Telone II most likely to result in groundwater contamination. Significant recovery of the chlorinated hydrocarbon compounds from the control treatment, using soil that had received prior fumigant applications, suggests that these compounds may be released from soil well after the time of fumigant application.
Subsurface Drainage Loss of Particles and Phosphorus from Field Plot Experiments and a Tile‐Drained Catchment
Authors: Laubel Anker , Jacobsen Ole H. , Kronvang Brian , Grant Ruth , Andersen Hans E. 
Published: July 2010

AbstractMovement of particles by water through the soil can be a significant pathway for P transport to surface waters in certain soil types. Our objective was to describe and quantify particulate matter (PM), particulate phosphorus (PP) and dissolved phosphorus (DP) transport tile drains during controlled plot experiments. The results were compared to corresponding studies of natural storm events in the tile‐drained catchment as a whole. Six rain simulations (irrigation 15.3–37 mm) were carried out at two 25 m2 plots on a loamy soil. Tracer chloride concentration in the drainage water peaked within 1 h of the onset of irrigation, thus indicating rapid macropore flow to the drains. PM, PP, and DP concentrations were highest in the initial drainage flow: 63 to 334 mg PM L−1, 0.177 to 0.876 mg PP L−1, and 0.042 to 0.103 mg DP L−1, respectively. Particulate matter and PP loss rates measured for the rapid drainage flow response were in the same range in the plot experiments as for nine precipitation events in the tile‐drained catchment (13.3 ha): 171 to 630 g PM ha−1 mm−1 vs. 141 to 892 g PM ha−1 mm−1, and 0.57 to 1.75 g PP ha−1 mm−1 vs. 0.71 to 5.92 g PP ha−1 mm−1, respectively. Tracer analysis using 137Cs revealed that the PM in the drainage water was derived from the topsoil.
Temporal and Spatial Patterns of Nitrate in a Claypan Soil
Authors: Ghidey F. , Alberts E. E. 
Published: July 2010

AbstractThe temporal and spatial patterns of NO3‐N were studied on a 35‐ha field located in the claypan soil region of north‐central Missouri. Soil samples were collected from the 0‐ to 5‐, 5‐ to 10‐, and 10‐ to 15‐cm depths and were analyzed for NO3‐N concentrations. Surface water samples from the field were collected for NO3‐N and NH4‐N analysis during each surface runoff event. Groundwater samples were also taken from the field wells four times a year for 5 yr and analyzed for NO3‐N concentrations. The effects of topography, depth to claypan, soil pH, organic matter (OM) content, cation exchange capacity (CEC), and soil water content on the spatial distribution of NO3‐N concentration were also evaluated. Nitrate‐N concentration in the 0‐ to 5‐cm soil depth increased in the first few weeks following application, then decreased rapidly and was very low at harvest. During the study period, nitrate movement below the layer of fertilizer application was very low, and <5% of the total N applied in the soil was lost to surface runoff. Nitrate‐N concentration in groundwater samples decreased by an average of 0.40 mg L−1 yr−1 from 1992 to 1996. The semivariograms did not exhibit strong spatial dependency except for the samples collected 1 and 4 wk after fertilizer applications in 1993 and 1995, respectively. Nitrate‐N concentration was poorly correlated to soil water content and depth to claypan and relatively strongly correlated to elevation and soil pH.
Leaching of Clopyralid and Metamitron under Conventional and Reduced Tillage Systems
Authors: Cox L. , Calderón M. J. , Hermosín M. C. , Cornejo J. 
Published: July 2010

AbstractThe influence of conventional tillage (CT) and reduced tillage (RT) on leaching of clopyralid (3,6‐dichloropyridine‐2‐carboxylic acid) and metamitron (4‐amino‐4,5‐dihydro‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5‐one) was monitored in a laboratory experiment with undisturbed soil columns from two plots where CT or RT practices have been used. Herbicides were applied at the rate of 5 kg ha−1 to duplicate water‐saturated columns that were leached with 600, 1200, or 1800 mL or 4000 mL of water. Clopyralid leaches more rapidly than metamitron due to its lower sorption. Higher amounts of clopyralid were detected in leachates from RT columns than in leachates from CT columns. Breakthrough of clopyralid occurred earlier in RT columns due to preferential flow, although the total amounts leached (78%) were lower than in CT columns (94%). Residual clopyralid in soil was only slightly lower in RT than in CT. Metamitron rendered similar BTCs in RT and CT although the total recovery in leachates were higher in CT columns (10%) than in RT columns (5%). Metamitron residues in soil were much lower in RT than in CT columns. Additional experiments with handpacked soil columns showed no differences in RT and CT for clopyralid, but higher leaching of metamitron in CT (16%) than in RT (8%). The lower recoveries (soil residue and leachates) observed for both herbicides under RT has been attributed to more rapid degradation in this system. These differences were much more pronounced for metamitron due to higher sorption and degradability in soil.
Methane Emission and Uptake from Soils as Influenced by Excreta Deposition from Grazing Animals
Authors: Yamulki S. , Jarvis S. C. , Owen P. 
Published: July 2010

AbstractThere have been only a few recent field‐based measurements to estimate the impact of excreta from grazing animals on methane (CH4) exchange. We report measurements of CH4 exchange from cattle dung and urine deposited in a simulated seasonal grazing pattern. Dung and urine samples were deposited on six separate experimental plots at different times of the year to simulate different stages of normal grazing under UK conditions to study the effects of environmental factors on CH4 exchange rates. During all the experiments, dung pats were the main emitter of CH4 with an estimated mean daily rate of 0.72 (range 0.21 to1.46) g CH4‐C per cow. Both net emission and consumption of CH4 from urine patches, however, were observed during the different experiments with a negligible mean daily emission of 0.02 (range −0.05 to 0.15) g CH4‐C per cow. Significant variations were observed between the experiments, despite the similarity of application rates and the composition of the excreta. These variations were mainly due to climatic differences when excreta were deposited: ambient temperature and rainfall were the most important factors. The estimated total annual emission of CH4 from cattle excreta deposition during the grazing season in the UK ranged between 0.42 and 3.26 (mean = 1.57) kt CH4‐C. Our work confirms other studies that suggest that excreta patches are insignificant sources of CH4 compared to the rumens of grazing cattle, and that climatic factors have a significant impact on CH4 emissions.
Nitrogen Recovery from Heat‐Dried and Dewatered Biosolids Applied to Forage Grasses
Authors: Cogger C. G. , Sullivan D. M. , Bary A. I. , Fransen S. C. 
Published: July 2010

AbstractBiosolids are stabilized solids from municipal wastewater treatment that meet federal criteria for land application. Limited information exists on N availability from biosolids treated to meet Class A standards for pathogen reduction. We conducted a 2‐yr field study at two locations in western Washington: (i) to evaluate N recovery from Class A biosolids applied to two cool‐season perennial grasses, and (ii) to make practical recommendations for biosolids application rates for intensive production of these grasses. We surface‐applied two types of Class A biosolids (heat‐dried and thermophilically digested‐dewatered) at three rates to a well‐drained soil planted to tall fescue (Festuca arundinacea Schreb.) and to a poorly‐drained soil planted to perennial ryegrass (Lolium perenne L.). Each location also had N fertilizer (34‐0‐0) and zero‐N control treatments. Grass was harvested at 30 to 50 d intervals during the growing season. The two types of biosolids were similar in their ability to supply N to the grasses. At the well‐drained site, application of 1100 to 1250 kg ha−1 of biosolids N over 2 yr produced similar grass yield and apparent N recovery as 540 kg ha−1 ammonium (NH4) nitrate (NO3)‐N. At the poorly‐drained site, application of 750 to 830 kg ha−1 biosolids N over 2 yr produced similar yield and apparent N recovery as 340 kg ha−1 NH4 NO3‐N. Residual soil NO3 in the fall was low at both locations and was not affected by the biosolids treatments. Comparison with other literature suggests that these materials are as effective as liquid biosolids at supplying N to forage grasses.
Use of Plaque Assay to Detect Enteric Viruses in a Rural Watershed
Authors: Brenner Fred J. , Brenner Elaine K. , Schwartz Todd E. 
Published: July 2010

AbstractWater samples were collected from four locations within the Munnell Run Watershed in Mercer County, Pennsylvania, and analyzed for fecal coliforms by MPN and enteric phages by plaque assay using Salmonella typhimurium WG 49 and Bacteroides fragilis HSP 40 as hosts. Fecal coliform concentrations and the number of phages varied seasonally (P < 0.001), as well as among the different sampling stations (P < 0.001). At all sampling stations positive for phages, S. typhimurium WG 49 PFUs outnumbered B. fragilis HSP 40 PFUs. Phages also were isolated from a septic discharge pipe and a wetland receiving septic drainage, but not from three avian species, 12 mammalian species, two streams without human wastes or from natural wetland, indicating that these viruses were of human origin. MPNs of fecal coliforms and S. typhimurium and B. fragilis PFUs were correlated with stream temperature (P < 0.001) and rainfall (P < 0.01). Only fecal coliforms and S. typhimurium WG 49 phages were correlated with suspended solids concentrations (P < 0.01). Likewise, there was a significant interaction among these parameters and MPNs of fecal coliform and HSP 40 and WG 49 PFUs (P < 0.001). The presence of host specific phages indicate the existence of septic discharges in the watershed, but both fecal coliforms and enteric viruses persist in stream systems, especially during the summer months.
Tillage Effects on Soil Nitrogen and Plant Biomass in a Corn‐Alfalfa Rotation
Authors: Rasse Daniel P. , Smucker Alvin J. M. 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.) stands have been reported to either decrease or increase nitrate (NO3) leaching, depending on tillage management. The fate of alfalfa‐generated N and its interaction with N fertilization in a subsequent corn (Zea mays L.) crop remains uncertain. Alfalfa contributions to corn yields and soil mineral N pools were studied under conventional tillage (CT) and no‐tillage (NT) systems over a 3‐yr corn—alfalfa—corn sequence. The field experiment compared CT vs. NT managements in fertilized and nonfertilized Kalamazoo loam soils (Typic Hapludalf). Four of the nonfertilized plots were equipped with undisturbed monolith lysimeters to monitor NO3 leaching. Living alfalfa stands lost 6 kg N ha−1 to deep leaching over a 1‐yr period, which is much less than the 20 kg NO3‐N ha−1 yr−1 lost by nonfertilized corn following corn. Within the first 6 mo following the spray‐killing of the stand, alfalfa plant tissue decomposition contributed to soil mineral N pools up to 115 kg N ha−1. During a dry year, all corn N requirements were met by plant tissue decomposition of alfalfa and soil organic matter mineralization, while applied N fertilizer accumulated in the soil profile and was highly susceptible to spring leaching. Similar quantities of N were lost to deep leaching from CT and NT systems during corn production, as higher drainage rates in NT systems were compensated by lower NO3‐N concentration of the leachates.