bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficiency of Hexane Extraction of Napropamide from Aldrich Humic Acid and Soil Solutions
Authors: Williams C. F. , Letey J. , Farmer W. J. , Nelson S. D. , Anderson M. , Ben‐Hur M. 
Published: July 2010

AbstractDissolved organic matter (DOM) has been shown to form a stable complex with Napropamide [2(α‐naphthoxy)‐N,N‐diethyl propionamide] and to facilitate its transport through soil columns. Liquid‐liquid extraction of organics is a common method to transfer napropamide from water into an organic phase for gas chromatography analysis. A study was conducted to determine the effect of Aldrich humic acid, soil‐derived dissolved organic matter, electrical conductivity, and hydrogen ion activity on the ability of hexane to extract napropamide from solutions and from soil extracts. The electrical conductivity of Aldrich humic acid solutions (0.0, 48, and 100 mg C L−1) were adjusted to 0.01, 0.97, and 1.69 dS m−1 by adding NaCl and CaCl2, and pH (8.2, 7.4, and 5.6) was adjusted using HCl and NaOH. Electrical conductivity had no effect on extraction efficiency. In the absence of DOM pH had no effect on extraction efficiency. Extraction efficiency decreased with increasing DOM concentration. Maximum reduction in extraction efficiency occurred in the presence of DOM when solution pH was near neutrality. A maximum extraction efficiency of 100% was observed in the absence of DOM and a minimum of 68% when napropamide was added to DOM solutions at pH 8.2 and then lowered to pH 5.6. Management practices such as liming and allowing napropamide to dry on the soil may increase environmental transport. Also quantification of napropamide in environmental samples can be affected by DOM.
Design and Characterization of a New Dialysis Chamber for Investigating Dissolved Organic Matter‐Organic Complexes
Authors: Williams C. F. , Farmer W. J. , Letey J. , Nelson S. D. 
Published: July 2010

AbstractEquilibrium dialysis is commonly used to measure the complex formed between dissolved organic matter (DOM) and pesticides such as napropamide [2(α‐naphthoxy)‐N,N‐diethyl propionamide]. Currently the dialysis method most often used employs dialysis tubing that is clamped on both ends. Limitations of the dialysis tubing method include difficulty in sample addition to the dialysis tubing, dilution effects, and the need for large sample volumes. A new dialysis chamber constructed of Teflon and using flat dialysis membranes is described and characterized using napropamide as a model compound. Using a dialysis membrane with a molecular weight cut off of 500 Daltons the system reached equilibrium across the membrane within 120 h. Significant sorption of napropamide to the membrane was observed. Napropamide sorption was linear, reversible, and dependant on the membrane used. Sample addition and removal from the chamber is possible without destroying the integrity of the membrane. The dialysis chamber allowed for fast and easy quantitative addition and removal of sample for dialysis without wasting sample. The small chamber made possible dialysis of very small samples (as little as 1.5 ml.) while maintaining a large surface area for diffusion. The chamber also provided dialysis with a maximum dilution factor of two since the volume of dialysate needed is equal to the volume of sample introduced.
Fate of Soil Applied Herbicides: Experimental Data and Prediction of Dissipation Kinetics
Authors: Baer U. , Calvet R. 
Published: July 2010

AbstractDissipation kinetics of several soil‐applied herbicides [atrazine (6‐chloro‐2 ethylamino‐4 isopropyl‐1,3,5‐triazine‐2,4 diamine), simazine (6‐chloro‐2,4‐diethyl‐1,3,5‐triazine‐2,4‐diamine), diuron (3‐(3,4‐dichloro‐phenyl)‐1,1‐dimethylurea), and sulcotrione (2‐(2‐chloro‐4‐mesyl‐benzoyl)cyclohexane‐1,3‐dione)] are studied at three sites having different climatic, pedological, and agronomical characteristics. Field data were obtained during 2 yr, 1993 and 1994. Information was completed by laboratory measurements of adsorption, desorption, and disappearance kinetics obtained at two temperatures (15 and 28°C) and two soil water contents (50 and 90% soil water capacity). Adsorption and desorption conform to the Freundlich description, sulcotrione being the less adsorbed. Laboratory disappearance kinetics can be approximately described with a first‐order law under some conditions. Calculated laboratory disappearance rate coefficients are used to simulate field dissipation kinetics in the 0‐ to 10‐cm soil layer, taking into account the effects of soil temperature (Arrhenius formula) and water content (Walker relation). Observed field dissipation kinetics, which are not fully described by a first‐order law, can be approximately simulated. Results are discussed from the points of view of agronomy and environment.
Multi‐Residue Analysis of Corn and Soybean Pesticides in Brazilian Oxisols Using Gas Chromatography and Mass Selective Detection
Authors: Laabs V. , Amelung W. , Zech W. 
Published: July 2010

AbstractAvailable methods for measuring pesticide residues in soils usually have not been tested for tropical soils nor do they cope with the spectrum of pesticides used in the tropics. An accurate and efficient method for the simultaneous determination of 14 corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] pesticides in Oxisols is presented in this study. The quantification of the pesticides was achieved using gas chromatography coupled with mass selective detection. For the extraction of aged pesticide residues from soil samples, combinations of acetone, ethylacetate, hexane, methanol, water, and salt solutions were tested. Of the 20 different solvent systems evaluated, the mixture of acetone‐ethylacetate‐water 2:2:1 (v/v/v) was most efficient for the extraction of all pesticides except metribuzine [4‐amino‐6‐ (1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,3‐ triazine‐5(4H)‐one]; this herbicide was recovered best by ethylacetate‐water4:1 (v/v). Different sample aging‐times (5–30d) did not affect the recovery of pesticides from incubated samples. Extraction of pesticides from field‐soil samples also was best with acetone‐ethylacetate‐water. No differences in extraction efficiency were observed between a simple shake extraction (4h) and batch extractions with an additional rise in temperature (60°C) or a sonication (30 min). The elimination of the water from the soil extract was achieved by a liquid‐liquid extraction with dichloromethane, which recovered the whole polarity spectrum of pesticides quantitatively. The method recovery from soil samples of freshly spiked pesticides averaged 94.8 ± 2.4%. The method was validated for Oxisols of contrasting clay and organic C content.
Field‐Scale Study of Chlortoluron Movement in a Sandy Soil over Winter: II. Modeling
Authors: Streck Thilo , Richter Jörg 
Published: July 2010

AbstractThis study was conducted to evaluate different modeling approaches for their ability to predict chlortoluron movement observed in a 4‐mo field study. The data base includes the results of a Br− transport experiment performed at the same site and of laboratory sorption‐desorption (SD) experiments. The approaches tested are based on the one‐dimensional convection dispersion equation (CDE) with two‐stage or equilibrium sorption. The CDE was applied either at the field scale or, to account for parameter variability, within a parallel soil columns (PSC) approach. Parallel soil column simulations were realized by the Monte Carlo (MC) method. Transport and sorption parameters and their distributions were estimated from Br− concentration profiles and SD isotherms, respectively. Chlortoluron degradation had been investigated in a joint project. The CDE with two‐stage sorption represented the movement of the chlortoluron peak well, but not its spreading. Similar results were obtained assuming equilibrium sorption, provided the same sorption parameters were used. If the sorption parameters were derived from the 1‐d sorption isotherm instead, displacement was overpredicted. Accounting for the variability of sorption and transport parameters through the PSC approach affected the simulation results only slightly. All simulations substantially underpredicted chlortoluron spreading, probably because the time scales of the laboratory and the field experiments were too different. To convert the estimated rate parameter to the appropriate time scale, we derived a simple formula that is based on the hypothesis of intrasorbent diffusion. Application of the CDE with the rescaled rate parameter distinctly improved the agreement between modeled and measured chlortoluron concentration profiles.
Stocking Method Effects on Nutrient Runoff from Pastures Fertilized with Broiler Litter
Authors: Kuykendall H. A. , Cabrera M. L. , Hoveland C. S. , McCann M. A. , West L. T. 
Published: July 2010

AbstractRepeated applications of broadcast broiler (Gallus gallus domesticus) litter can increase nutrient runoff from pastures. Rotational stocking (RS) of cattle, as compared with continuous stocking (CS), may be useful in decreasing surface nutrient runoff because of better manure distribution and more uniform forage accumulation to act as filters and trap nutrients. Our objective was to measure nutrient runoff from six 0.75‐ha tall fescue (Festuca arundinacea Schreb.)—common bermudagrass [Cynodon dactylon (L.) Pers.] pastures fertilized with 13 to 15 Mg (dry weight) broiler litter per hectare per year and managed under RS or CS. Two cross‐bred beef (Bos taurus) steers were maintained on each pasture year around for 2 yr, with additional steers added to maintain similar forage availability between stocking methods. In each pasture, surface runoff was directed to a flume where it was sampled by an automatic sampler. Runoff was analyzed for total Kjeldahl N, (NO−3 + NO−2)−N, NH+4‐N, total Kjeldahl P, and dissolved reactive P (DRP). Grazing method had no effect (P > 0.10) on surface runoff quality or quantity. Average runoff expressed as a percentage of the rain was 15% for the first year and 12% for the second year. The average flow‐weighted concentrations of DRP and NH+4‐N were 5.08 mg P L−1 and 1.07 mg N L−1 for the first year, and 8.22 mg P L−1 and 10.11 mg N L−1 for the second year (P < 0.10).
Precipitation Effects on Sediment and Associated Nutrient Discharges from Rhode River Watersheds
Authors: Correll David L. , Jordan Thomas E. , Weller Donald E. 
Published: July 2010

AbstractTotal suspended sediment (TSS) concentrations and their nutrient composition were studied in discharges from seven contiguous small watersheds on the Atlantic Coastal Plain in Maryland for up to 22 yr. All watersheds were equipped with V‐notch weirs and volume‐integrating, flow‐proportional samplers. Spot samples were also taken for analysis of TSS concentrations and the composition of dissolved and particulate nutrients at known water discharge rates. Interannual variations in annual and seasonal precipitation during this study spanned approximately the range of 160‐yr weather records in the vicinity. Mean annual TSS fluxes were 263, 546, 134, and 92 kg ha−1 for the area‐weighted mean of the overall Rhode River watershed, and for subwatersheds that were primarily‐cropland, completely forested, and grazed, respectively. TSS fluxes were highest in the summer, followed by spring, winter, and fall. Regressions of TSS flux vs precipitation were used to calculate TSS fluxes for seasons and years with average, above and below the average precipitation. TSS flux from the Rhode River watershed was 12‐fold higher in very wet years than in very dry years and 271‐fold higher in very wet summers than in very dry summers. At base flow, TSS had high nutrient content, but as flow rates increased TSS nutrient content rapidly declined. At base flow, most of the total‐P, TPi, TKN, and organic‐C was in the dissolved phase, while at higher flows, most of these nutrients were in the TSS phase.
Responses of Boreal Plants to High Salinity Oil Sands Tailings Water
Authors: Renault S. , Paton E. , Nilsson G. , Zwiazek J. J. , MacKinnon M. D. 
Published: July 2010

AbstractIn the extraction of bitumen from oil sands ore, large volumes of railings water (CT water) containing elevated levels of Na, sulfate, bicarbonate and chloride are produced. High salinity process waters will probably affect terrestrial reclamation options. The present study tested the impact of tailings waters on boreal forest species including aspen (Populus tremuloides Michx.), buffalo berry [Sheperdia canadensis (L.) Nutt], northwest hybrid poplar (Populus deltoides × Populus balsamifera), dogwood (Cornus stolonifera Michx.), jack pine (Pinus banksiana Lamb.), and white spruce [Picea glauca (Moench) Voss]. Seedlings were grown in solution culture containing mineral nutrients and different dilutions of CT water, with and without supplemental salts (Na2SO4 and NaCl). After 4 wk of treatment, dogwood, hybrid poplar, and buffalo berry showed relatively high resistance to saline CT waters. Conifer seedlings developed leaf necrosis in all treatments, while aspen seedlings rapidly lost their foliage and produced new leaves. In comparison to the controls, elevated Na levels were measured in plant tissue of all species grown in CT water. However, some differences between species were observed, with jack pine seedlings showing much higher Na content than aspen, dogwood, or hybrid poplar. In hybrid poplar, the accumulation of Na was accompanied by a significant reduction in K, Mg, Ca, and P. Buffalo berry, aspen, jack pine, and white spruce showed elevated levels of S after growth in the sulfate‐enriched CT waters. High tissue Na content did not induce leaf injury in dogwood, hybrid poplar and buffalo berry, suggesting possible Na resistance.
Comparison of Simulated Forest Responses to Biosolids Applications
Authors: Luxmoore R. J. , Tharp M. L. , Efroymson R. A. 
Published: July 2010

AbstractOrganic matter and N are added to humus pools of the LINKAGES simulator of forest growth and N cycling at a range of application rates to investigate long‐term effects of biosolids (sewage sludge) on forest productivity. Two conifer plantations (Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco var. menziesii], loblolly pine [Pinus taeda L.]) and a northern hardwood forest located in contrasting climatic regions are investigated. Single applications of biosolids are given at 0, 5, 10, 20, and 40 Mg/ha, and multiple applications are given on seven occasions at 3‐yr intervals at rates of 5 and 10 Mg/ha. Highly significant increases in aboveground phytomass and net primary productivity of Douglas‐fir plantations are obtained in a 100‐yr simulation with increasing biosolids application rates. Results for loblolly pine from a 50‐yr simulation produced about half the growth response of Douglas‐fir. Long‐term simulations of northern hardwoods showed modest growth responses and small increases in NPP with added biosolids.. The phytomass of one overstory and three understory species in the hardwood forest changed in response to different biosolids applications and varying species sensitivity to N supply. Biosolids are a significant resource for enhancing forest productivity, particularly in conifer plantations. Estimates of N leaching losses from simulated forest sites combined with a literature review of leaching losses suggest that biosolids applications at 3‐yr intervals with rates less than 8.5 Mg/ha (0.4 Mg N/ha) during active forest growth may pose little offsite contamination risk to ground water or surface waters.
Estimation of Nitrate Contamination of an Agro‐Ecosystem Outwash Aquifer Using a Nitrogen Mass‐Balance Budget
Authors: Puckett Larry J. , Cowdery Timothy K. , Lorenz David L. , Stoner Jeffrey D. 
Published: July 2010

AbstractA mass‐balance budget of N cycling was developed for an intensive agricultural area in west‐central Minnesota to better understand NO−3 contamination of ground water in the Otter Tail outwash aquifer. Fertilizer, biological fixation, atmospheric deposition, and animal feed were the N sources, and crop harvests, animal product exports, volatilization from fertilizer and manure, and denitrification were the N sinks in the model. Excess N, calculated as the difference between the sources and sinks, was assumed to leach to ground water as NO−3. The budget was developed using ground water data collected throughout the 212‐km2 study area. Denitrification was estimated by adjusting its value so the predicted and measured concentrations of NO3 in ground water agreed. Although biological fixation was the largest single N source, most was removed when crops were harvested, indicating that inorganic fertilizer was the primary source of N reaching the water table. It was estimated that denitrification removed almost half of the excess NO−3 that leached below the root zone. Even after accounting for denitrification losses, however, it was concluded that the ground water system was receiving approximately three times as much N as would be expected under background conditions.
Development of Pedotransfer Functions to Quantify Phosphorus Saturation of Agricultural Soils
Authors: Kleinman Peter J. A. , Bryant R. B. , Reid W. S. 
Published: July 2010

AbstractSoil P saturation affects the risk of P loss to surface and ground water and is therefore a critical environmental indicator in regions where eutrophication is a concern. In the USA, most soil testing laboratories do not include environmental indicators such as soil P saturation as standard soil test options. Development of pedotransfer functions that relate soil test data to soil P saturation, however, would enable soil testing laboratories to estimate soil P saturation as part of soil test results without significant additional expenditures. This study examines associations between readily‐available soil test data (pH, soil organic matter, and extractable P, Al, Fe, and Ca) and soil P saturation as estimated by acid ammonium oxalate extraction. Fifty‐nine soil samples were collected from the Delaware River Watershed in New York State (42°21′N, 74°52′W) and subjected to standard soil test analyses as well as to acid ammonium oxalate extraction. Some soil test variables were well correlated with soil P saturation. As a single predictor, soil test P was most highly correlated to soil P saturation (r = 0.88). This association supports the use of soil test P as an environmental indicator. Soil test Al also was well correlated with soil P saturation following logarithmic transformation (r = 0.73). Multivariate pedotransfer functions containing soil test P, Al, Fe, soil organic matter, and pH did not significantly improve estimation of soil P saturation (R = 0.91) above soil test P alone.
Prospects for Minimizing Phosphorus Excretion in Ruminants by Dietary Manipulation
Authors: Valk H. , Metcalf J. A. , Withers P. J. A. 
Published: July 2010

AbstractIn most intensive dairy farms, P input exceeds output, causing potential P losses to the environment, which results in leaching to ground water and eutrophication. Phosphorus in fertilizer and purchased feeds are the main contributors to P input, whereas milk P is the main output. In the Netherlands, new legislation has been introduced to substantially reduce P surpluses. However, since P is essential for maintenance and milk production, the dietary P supply must be maintained, especially for high‐yielding dairy cows. This paper reviews how dairy cow diets can be manipulated to reduce potential P‐loss to the environment without negative effects on animal health, feed intake, or milk production. The availability of P in forages, purchased feed, and inorganic phosphate supplements for ruminants may differ substantially and more research work is needed to elucidate the relevant factors influencing feed P availability. There is a lack of understanding of how and to what extent P is absorbed from the small intestine and the relationship to hydrolysis and microbial P utilization in the rumen. Comparing national P requirement systems indicates that the systems used in the UK and Italy should be revised to minimize unnecessary P accumulation in the soil. In addition, the impact of manipulating the dietary P supply to decrease P losses from dairy farming systems is evaluated. Whole farm system studies have illustrated the potential environmental benefits of more closely monitoring imports of purchased feeds onto the farm.
A Review of New Zealand Research Measuring Phosphorus in Runoff from Pasture
Authors: Gillingham Allan G. , Thorrold Bruce S. 
Published: July 2010

AbstractNew Zealand pastoral farm land is intensively grazed and receives predominantly single superphosphate fertilizer. Resource managers and policymakers are concerned about the effects of such land use on P enrichment of waterways and lakes. This paper reviews New Zealand research on the effects of agricultural land use on P losses in water runoff and highlights priorities for management and future research. Diffuse agricultural sources contribute about 91% of total P entering fresh waters annually, with 0.11 to 1.67 kg P ha−1 yr−1 being removed, mostly in particulate forms. Despite a number of studies showing good site‐specific correlation, no widely applicable soil test method for estimating runoff dissolved P concentration has been found. The effects of (i) fertilizer application in increasing surface runoff P concentrations (ii) riparian areas in both source and control roles, and (iii) subsurface drainage, in reducing losses of P in surface runoff from pasture land, are reported. A catchment scale simulation model, Basin New Zealand (BNZ), for intensively grazed pastures, has been produced based on CREAMS (chemicals, runoff, and erosion from agricultural management systems). This model adequately predicts P loss at the field scale but is less reliable at the catchment scale, which indicates differences in predominant P and sediment sources at the two scales. Corrective management has alleviated eutrophication problems in some lakes and waterways; however better information is yet required to understand, model, and manage the more insidious losses of P to waterways from New Zealand farm land.
Arsenic Speciation: Involvement in Evaluation of Environmental Impact Caused by Mine Wastes
Authors: Roussel Christophe , Bril Hubert , Fernandez Angel 
Published: July 2010

AbstractSince large areas have been contaminated by arsenic‐rich industrial and mining by‐products in several countries, knowledge of arsenic (As) behavior in soils and water is of major concern for reclamation of polluted sites and evaluation of environmental risk. Cheni's tailings (France) contains average concentrations up to 7000 mg kg−1 As and was listed by the authority as an important potentially pollutant site. Because As speciation determines its mobility, it was investigated in surface and ground waters of the site and a study of the solid As‐bearing phase was performed on suspended particulate material (SPM). Results of sequential extraction, carried out on the SPM collected in drainage waters, show that most of total extracted As (78%) and Fe (77%) is bound to an iron hydrous oxide phase, which was determined to be lepidocrocite (γ‐FeOOH) by x‐ray diffraction and infrared spectrometry. Particulate material was >220 times more concentrated than dissolved As. Conditions for the stability of dissolved (<0.45 µm) arsenite [As(III)] and arsenate [As(V)] are discussed on the basis of thermodynamical data and field measurements of pH and redox potentials. The theoretical stability of As(V) corresponds to a large association between As and particulate material, and large amounts of the metalloid are released in solution when As‐rich particles come from oxidized ground waters to moderately reduced conditions. These results are important for evaluating, modeling, and rehabilitating As‐polluted sites.