bluuebunny/crossref_metadata_2025_split huggingface dataset:
TNT Transport and Fate in Contaminated Soil
Authors: Comfort S. D. , Shea P. J. , Hundal L. S. , Li Z. , Woodbury B. L. , Martin J. L. , Powers W. L. 
Published: July 2010

AbstractPast disposal practices at munitions production plants have contaminated terrestrial and aquatic ecosystems with 2,4,6‐trinitrotoluene (TNT). We determined TNT transport, degradation, and long‐term sorption characteristics in soil. Transport experiments were conducted with repacked, unsaturated soil columns containing uncontaminated soil or layers of contaminated and uncontaminated soil. Uncontaminated soil columns received multiple pore volumes (22–50) of a TNT‐3H2O pulse, containing 70 or 6.3 mg TNT L−1 at a constant pore water velocity. TNT breakthrough curves (BTCs) never reached initial solute pulse concentrations. Apex concentrations (C/Co) were between 0.6 and 0.8 for an initial pulse of 70 mg TNT L−1 and 0.2 to 0.3 for the 6.3 mg TNT L−1 pulse. Earlier TNT breakthrough was observed at the higher pulse concentration. This mobility difference was predicted from the nonlinear adsorption isotherm determined for TNT sorption. In all experiments, a significant fraction of added TNT was recovered as amino degradates of TNT. Mass balance estimates indicated 81% of the added TNT was recovered (as TNT and amino degradates) from columns receiving the 70 mg TNT L−1 pulse compared to 35% from columns receiving the 6.3 mg TNT L−1 pulse. Most of the unaccountable TNT was hypothesized to be unextractable. This was supported by a 168‐d sorption experiment, which found that within 14 d, 80% of 14C activity (added as 14C‐TNT) was adsorbed and roughly 40% unextractable. Our observations illustrate that TNT sorption and degradation are concentration‐dependent and the assumptions of linear adsorption and adsorption‐desorption singularity commonly used in transport modeling, may not be valid for predicting TNT transport in munitions‐contaminated soils.
Nitrogen Loss from a Soil Restored after Surface Mining
Authors: Davies R. , Hodgkinson R. , Younger A. , Chapman R. 
Published: July 2010

AbstractAnaerobic conditions develop below about 1‐m depth in soil stockpiles and this can lead to an accumulation of ammonium (NH+4) and transformations of a normally relatively inert organic‐N pool within the soil. After reinstatement of the soil from the stockpile, the NH+4 may rapidly be transformed to nitrate (NO−3) and lost from the soil with the labile organic‐N. These losses may lead to a pollution risk in addition to the loss of a resource. The magnitude of N losses were measured from a soil that had been reinstated for agricultural use after being stored in a stockpile for 12 yr. Nitrogen movement in the soil profile and losses into the water‐course were monitored for 2 yr beginning immediately after reinstatement. Relatively large movements of N were detected within the soil profile and large losses to the atmosphere and/or water‐courses were estimated. Over the 2‐yr monitoring period, 2449 kg ha−1 of N was lost from the soil profile; 90% of this was not accounted for either in the soil or in the runoff or drainage water as mineral‐N and was presumed to have entered either the atmosphere or aquatic environment as organic‐N. To aid remedial measures, the proportion entering the atmosphere as nitrogen and nitrous oxides or the aquatic environment as organic‐N, needs further investigation.
Experimental Evidence of Transport of Pesticides through Field Soils—A Review
Authors: Flury Markus 
Published: July 2010

AbstractMuch information is available in the literature about pesticide transport through soils at the field scale. The purpose of this study is to review the literature with a focus on pesticide leaching to groundwater. The literature was compiled and discussed with respect to different factors that influence pesticide leaching. Pesticide leaching below the root zone has been demonstrated in sandy as well as in loamy soils. Particularly in loamy soils, there is evidence that even strongly adsorbing chemicals can move along preferential flow pathways and that the travel times of pesticides are comparable to those of conservative solutes. The amounts of pesticides leached below the root zone by worst case rainfall events depend on the chemical properties and can reach up to 5% of the applied mass. When there is no heavy rainfall shortly following application of chemicals, the mass annually leached below the root zone is in the range of <0.1 to 1%, occasionally it can reach up to 4%. Although a direct comparison cannot be made, the mass lost by leaching seems generally to be smaller than that lost by runoff, depending of course on the slope of the fields. Several factors that affect pesticide leaching, such as surface preparation, soil structure, soil water content, type of irrigation, pesticide formulation, time of application and rainfall events, are discussed with support of experimental evidence. While some factors showed inconsistent effects, others show promise in controlling leaching mechanisms. These latter factors include initial water content, surface preparation, and time of pesticide application. Based on the reviewed literature, recommendations were made for future research activities.
Phosphorus Losses in Irrigation Runoff from Fertilized Pasture
Authors: Austin Nick R. , Prendergast J. Bernard , Collins Matthew D. 
Published: July 2010

AbstractRunoff from flood‐irrigated perennial pastures contains significant loads of P. Factors affecting the P load in runoff are unknown, and there are no guidelines currently available for management of phosphatic fertilizers to reduce runoff P loads. This study was conducted to determine the relationship between single superphosphate application rate and runoff P concentration. Four rates of single superphosphate (250, 500, 750, and 1000 kg/ha) were applied to 12 30 by 8‐m flood irrigated bays in a randomized design, on a Lemnos loam (Natric Xeralf), in the Shepparton Irrigation Region, Victoria, Australia. In runoff, total P (TP), filtrable reactive P (FRP) concentrations and EC increased linearly with application rate, with initial concentrations (5 min) being significantly higher than those later in a runoff event (P < 0.025). In the irrigation directly following fertilizer application the depth of irrigation water that infiltrated (calculated from volume balance) was in direct proportion to single superphosphate application rate (P = 0.03). Normalized runoff losses of single superphosphate in consecutive irrigations followed a single exponential decay. The primary loss mechanism for P following single superphosphate application was through dissolution, rather than sediment transport.
Forms of Cadmium, Lead, and Zinc in Contaminated Soils from Southwest Poland
Authors: Chlopecka Anna , Bacon J. R. , Wilson M. J. , Kay J. 
Published: July 2010

AbstractThe metals Cd, Pb, and Zn occurring in Haplorthods and Haplumbrepts of both sandy and loamy textures in the vicinity of Tarnowskie Gory in southwest Poland, an area that has been subjected to severe metal contamination, were studied according to a procedure based on sequential extraction analysis. Concentrations of the metals ranged from background levels to levels well in excess of the maximum tolerable limits in agricultural soils. Thus, Cd, Pb, and Zn ranged from 0.2 to 103, 14 to 7100 and 20 to 10 000 mg kg−1 soil, respectively. Soil type, texture, organic matter, and cation exchange capacity (CEC) did not influence the relative proportions of heavy metal forms in any consistent manner. However, the influence of soil pH was clear. Soil samples of pH < 5.6 contained relatively more of all metals in the exchangeable form than in samples where pH was >5.6. The most consistent distribution patterns were found when the soil samples were grouped according to their total metal contents. The inferred relative mobility of the metals and their redistribution among the different fractions are generally consistent with the findings of previous studies of contaminated soils and support the view that metals from anthropogenic sources are more mobile than those from soil parent materials.
Nitrate Leaching Losses Under Repeated Cattle Feedlot Manure Applications in Southern Alberta
Authors: Chang C. , Entz T. 
Published: July 2010

AbstractAn experiment was conducted at Lethbridge, Alberta, to determine the long‐term effects of annual applications of cattle manure on nitrate (NO3)‐N accumulation and movement, and to assess the environmental impact of such a practice. Manure was applied annually at 0, 30, 60, and 90 Mg ha−1 (wet wt. basis) and 0, 60, 120, and 180 Mg ha−1 (zero, one, two, and three times the maximum recommended annual application rate, respectively), to nonirrigated and irrigated Dark Brown Chernozemic (Typic Haploboroll) clay loam soils from 1973 to 1992. All plots were planted to barley (Hordeum vulgare L. cv. Galt) in spring each year. In the fall, duplicate soil cores were taken to a depth of 1.5 m. Water content (gravimetric), chloride, ammonium‐ and NO3‐N concentration of soil and manure samples were determined to estimate leaching and deep percolation loss of water and solutes. Level of manure and moisture regime affected the extent of NO3‐N increases. Under nonirrigated conditions, manure applied at one to three times the recommended rate resulted in a significant accumulation of NO3‐N in the root zone. However, minimal leaching loss was observed below 1.5 m except for a year with unusually high precipitation. On irrigated soils, contamination of soil and groundwater from repeated applications at or greater than the recommended rate of 60 Mg ha−1 was significant and annual losses may reach 93 to 341 kg N ha−1. Therefore, long‐term annual application of manure at the maximum recommended level is not advised because of potential soil and water contamination problems.
Volatilization of EPTC: Simulation and Measurement
Authors: Baker J. M. , Koskinen W. C. , Dowdy R. H. 
Published: July 2010

AbstractMany of the organic chemicals used in agricultural production are susceptible to loss from the soil surface to the atmosphere by volatilization. Adequate prediction of the impact of these chemicals on the environment thus requires consideration of both downward movement through the soil to groundwater and upward movement in the gas phase to the atmosphere. We developed a method to mechanistically simulate volatilization within the framework of a conventionally formulated solute transport model and used it to simulate the gas‐phase losses of EPTC, a commonly used volatile herbicide. The model considers efflux of a trace gas at the soil surface to be a process of unsteady diffusion, interrupted intermittently by dispersive events that can be thought of as eddies at the innermost scale. Model results were compared to measurements of volatilization during the first 7 d following application of EPTC, conducted with a Bowen ratio system in a 17‐ha field at Rosemount, MN. The measurements indicated a relatively large initial flux (ca. 150 g ha−1 h−1) that rapidly decreased to negligible levels within a day following application. The model agreed reasonably well on the first day, if a measured value for Henry's constant was used rather than a value estimated from the saturation vapor pressure and the solubility. However, on subsequent days the model considerably overestimated volatilization, regardless of the Henry's constant that was used. It is likely that hysteresis in sorption/desorption, particularly as surface soil dries following herbicide incorporation, may be the primary reason why volatile losses are lower than might be predicted on the basis of equilibrium partitioning theory.
Methyl Bromide Emissions from a Covered Field: I. Experimental Conditions and Degradation in Soil
Authors: Yates S. R. , Gan J. , Ernst F. F. , Mutziger A. , Yates M. V. 
Published: July 2010

AbstractAn experiment is described to investigate the environmental fate and transport of methyl bromide in agricultural systems. The experiment was designed to determine the dynamics of methyl bromide movement through soil, degradation, and total emissions to the atmosphere. This is of particular interest because it will allow an assessment of the environmental impacts (i.e., stratospheric ozone depletion) resulting from the agricultural use of methyl bromide. Methyl bromide was applied at a rate of 843 kg in a 3.5‐ha (i.e., 240 kg/ha) field at a depth of 0.25 m and covered with a sheet of 1‐mil polyethylene plastic. The maximum methyl bromide concentration in the atmosphere occurred at night between 0200 and 0600 h. During the first 3 d of the experiment, the maximum daily concentrations at 0.2 m above the soil surface were 30, 5, and 1 mg/(m3 of air), respectively. The trend of reduced emissions with time continued until the plastic was removed, when a momentary increase in the methyl bromide emissions occurred. The maximum soil gas concentration 24 h after injection was 30 g/m3 located at a 0.25‐m depth. When the plastic was removed from the field (at 5.6 d), the maximum soil gas concentration was approximately 2 g/m3 at a 0.5‐m depth. A mass‐difference method for estimating the total methyl bromide emissions from the soil, based on degradation of methyl bromide to Br−, indicates that approximately 39% or 325 kg (± 164 kg) of the applied methyl bromide was converted to Br− and, therefore, 61% or 518 kg (±164 kg) was lost via volatilization.
Methyl Bromide Emissions from a Covered Field: II. Volatilization
Authors: Yates S. R. , Ernst F. F. , Gan J. , Gao F. , Yates M. V. 
Published: July 2010

AbstractAn experiment to investigate the environmental fate and transport of methyl bromide in agricultural fields is described. The methyl bromide volatilization rate was determined as a function of time for conditions where methyl bromide was applied at a rate of 843 kg in a 3.5‐ha (i.e., 240 kg/ha) field covered with plastic at a depth of 25 cm. Three methods were used to estimate the methyl bromide volatilization rate, including: the aerodynamic, theoretical profile shape and integrated horizontal flux methods. The highest methyl bromide volatilization rates were at the beginning of the experiment. Within the first 24 h, approximately 36% of the applied methyl bromide mass was lost. Diurnally, the largest volatilization rates occurred during the day when temperatures were high and the atmosphere was unstable. Cooler temperatures, light winds, and neutral to stable atmospheric conditions were present at night, reducing the flux. The total emission calculated using these methods was found to be approximately 64% (±10%)of the applied mass. A mass balance was calculated using each flux estimation technique and several methods for analyzing the data. The average mass recovery using all the flux methods was 867 kg (±83 kg), which was 102.8% (±9.8%) of the applied mass (i.e., 843 kg). The range in the mass balance percent (i.e., percent of applied mass that is measured) is from 88 to 112%. The averaged mass balance percent for the aerodynamic method, which involved using the measured data directly, was approximately 100.8%. The total emission calculated using the aerodynamic method was found to be approximately 62% (± 11%) of the applied mass.
Influence of Controlled Drainage‐Subirrigation on Surface and Tile Drainage Nitrate Loss
Authors: Drury C. F. , Tan C. S. , Gaynor J. D. , Oloya T. O. , Welacky T. W. 
Published: July 2010

AbstractControlled drainage‐subirrigation (CDS), conservation tillage, and corn (Zea mays L.) production practices were evaluated as methods of reducing NO−3 loss through tile drainage. Controlled drainage‐subirrigation was used to manage water from precipitation and subirrigation. Samples of tile drainage (5801) and surface runoff (3274) water were collected with autosamplers during each runoff event over a 3‐yr period. Annual tile drainage volumes were reduced 24% with CDS compared with the drainage (DR) treatments. Flow weighted mean NO−3 concentration of tile drainage water was reduced 25% from 10.6 mg N L−1 for the DR treatments to 7.9 mg N L−1 for the CDS treatments. The average annual NO−3 loss was reduced 43% from 25.8 kg N ha−1 for the DR treatment to 14.6 kg N ha−1 for the CDS treatments. Eighty‐eight to 95% of the NO−3 losses from all treatments occurred in the noncrop period (1 Nov.–31 Apr.). Conservation tillage in combination with CDS reduced annual NO−3 losses 49% (11.6 kg N ha−1) when compared with the conventional moldboard plow tillage and DR treatment. Annual NO−3 loss through surface runoff was increased to 1.9 kg N ha−1 with the CDS treatments compared with 1.4 kg N ha−1 with the DR treatment, this loss was minor compared with losses incurred through tile drainage. Controlled drainage‐subirrigation is a technological advancement in soil and water management as it enables farmers to minimize the effect of dry summers on crop growth and reduce NO−3 contamination of drainage water.
Laboratory Scale In‐Vessel Composter Designed for Volatile Emissions Analysis
Authors: Spongberg A. L. , Thomas J. C. , Brown K. W. 
Published: July 2010

AbstractAirtight laboratory scale in‐vessel composters equipped to capture gaseous emissions were constructed from modified portable cement mixers. Any compounds that are volatilized during composting can be collected from the exiting air stream and quantified using gas chromatography. Measurements of the amount of each compound vaporized and its residual concentration can be used to determine air quality impacts and degradation rates.
Applications of GIS to the Modeling of NonPoint Source Pollutants in the Vadose Zone: A Conference Overview
Authors: Corwin D. L. , Wagenet R. J. 
Published: July 2010

AbstractBecause of their ubiquitous nature and potential chronic health effects, nonpoint source (NPS) pollutants have become a focal point of attention by the general public, particularly regarding pollution of surface and subsurface drinking water sources. The NPS pollutants pose a technical problem because of the areal extent of their contamination that increases the complexity and sheer volume of data far beyond that of point‐source pollutants. The spatial nature of the NPS pollution problem necessitates the use of a geographic information system (GIS) to manipulate, retrieve, and display the large volumes of spatial data. This overview provides a brief introduction and review of the modeling of NPS pollutants with GIS and a brief discussion of some of the papers presented at the ASA‐CSSA‐SSSA 1995 Bouyoucos Conference entitled Applications of GIS to the Modeling of Nonpoint Source Pollutants in the Vadose Zone.
Determination of Nonpoint‐Source Pollution Using GIS and Numerical Models
Authors: Zhang R. , Hamerlinck J. D. , Gloss S. P. , Munn L. 
Published: July 2010

AbstractA geographic information system (GIS) was utilized to apply a modified DRASTIC method to the assessment of ground water contamination sensitivity in Goshen County, Wyoming. Several basic environmental characteristics, identified as influencing contaminant transport through the vadose zone to groundwater systems, were mapped, automated, and analyzed. These characteristics include: depth to groundwater, net recharge, hydrogeologic setting, vadose zone soil properties, land surface slope, and saturated hydraulic conductivity. Sensitivity ratings were developed for each parameter based on a combination of mathematical functions and the inherent capacity of each characteristic to influence transport of contaminants. A raster‐based overlay analysis was performed to derive a map that portrays cumulative aquifer sensitivity ratings across the county, providing a relative indication of groundwater vulnerability to contamination. A process‐based numerical model was used to simulate water flow and solute transport in the vadose zone and groundwater systems. The model incorporated soil and hydraulic properties produced with the GIS into the simulations. Numerical simulations described the time and spatial distributions of contaminants. Chemical mass stored in the soil and leaching out from the vadose zone were computed to characterize groundwater contamination. Groundwater sensitivity indexes, which were developed based on the numerical modeling results, were compared with the GIS sensitivity map and used to verify the reliability of the map.
Use of Logistic Regression and GIS Modeling to Predict Groundwater Vulnerability to Pesticides
Authors: Teso Roberto R. , Poe Minn P. , Younglove Theodore , McCool Patrick M. 
Published: July 2010

AbstractSoils are considered important components of many pesticide contamination models and are frequently the direct or indirect targets of pesticides applied during agricultural activities. Soil texture is commonly referenced on pesticide labels as an important factor in the selection and application of pesticides and in identifying target areas that are vulnerable to leaching. In general, no guidelines exist for the common interpretation of generic soil texture terms found on pesticide labels, for example, coarse or coarse‐textured soils. In the present study, a significant logistic regression model (P = 0.017) was developed that is based on the soil particle‐size class composition of sections containing wells sampled for DBCP (1,3‐dibromochloropropane). Particle‐size class is a concept used in Soil Taxonomy to describe soil family texture and is a component of soil family names. The model contains terms for the sandy and fine particle‐size classes. The model was validated using data obtained from sources independent of those used to develop the model. Records in the California Soils Map Unit Inventory database that describes the soil map unit composition of >65 000 sections (1600 m2 or 1 mi2) were used to generate probability scores for >15 000 sections located in the San Joaquin Valley, CA. A geographic information system, an information management technique that is becoming an accepted tool for a wide range of regulatory agencies, was used to generate visual images of the probability scores. A map was developed that depicts four distinct probability classes of the DBCP‐contamination status of section‐sized areas and their distribution within the study area.