bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tillage and Controlled Drainage‐Subirrigated Management Effects on Soil Persistence of Atrazine, Metolachlor, and Metribuzin in Corn
Authors: Gaynor J. D. , Tan C. S. , Ng H. Y. F. , Drury C. F. , Welacky T. W. , van Wesenbeeck I. J. 
Published: July 2010

AbstractThe occurrence of herbicides in surface waters necessitates the development of management practices to reduce herbicide loss through tile drainage and surface runoff. Four tillage‐intercrop systems: moldboard plow (MB), moldboard plow with rye grass (Lolium multiflorum Lam.) intercrop (MB+IC), soil saver (SS), and soil saver with rye grass intercrop (SS+IC), and two water table management treatments: controlled drainage‐subirrigation (CDS) and no control drainage (D) were investigated for their effect on herbicide persistence. Atrazine [2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine] (1.1 kg ha−1), metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] (0.5 kg ha−1), and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] (1.68 kg ha−1) were strip applied in a corn (Zea mays L.) management system to reduce herbicide inputs 50%. Tillage‐intercrop system had little consistent effect on soil residues of the herbicides at 0‐ to 10‐cm depth. Control drainage‐subirrigation decreased haif‐life of atrazine and metolachlor in one of two years. Half‐life for atrazine ranged from 34 to 56 d, metribuzin 24 to 35 d, and metolachlor 40 to 79 d, with longer half‐life in dry years. Des‐ethyl atrazine [2‐chloro‐4‐amino‐6‐isopropylamino‐s‐triazine], the major metabolite of atrazine, persisted along with atrazine and metolachlor to the next planting season. Less than 10% of the original herbicide application was recovered the year following application. It was concluded that environmental factors such as rain affect herbicide residues more than cultural practices.
Adsorption of Sulfometuron and Other Anions on Pillared Clay
Authors: Polubesova Tamara , Undabeytia Tomas , Nir Shlomo , Chertkova Lubov , Van Damme Henri , Annabi‐Bergaya Faiza 
Published: July 2010

AbstractThe adsorption of several anions of agronomic and ecological importance, sulfometuron 2‐[3‐(4,6‐dimethylpyrimidin‐2‐yl)ureidosulfonylbenzoic acid, sulfate, acetate, and chloride on pillared clay was studied. Pillared clay (PC) is a very effective adsorbent of anions from aqueous solutions. The fractions of sulfometuron adsorbed from aqueous solutions were more than 90% of added, but low solubility limited the added amounts. The maximal adsorbed amount of sulfate was 0.72 molc kg−1 and of acetate was 0.41 molc kg−1. Addition of 100 and 500 mM of NaCl as the background electrolyte did not affect the adsorption of sulfometuron, but drastically reduced the adsorption of sulfate and acetate. Acetate at 1000‐fold larger excess competes with sulfometuron for the surface sites, but sulfate does not. Acetate decreased dramatically the adsorption of sulfate when both anions were added simultaneously, but acetate did not adsorb on the clay with pre‐adsorbed sulfate. The sequence of adsorption affinity of anions to the PC surface is: sulfometuron >> sulfate > acetate >> chloride. The binding coefficient was 12 000 M−1 for sulfometuron, 650 M−1 for sulfate, 350 M−1 for acetate, and 15 M−1 for chloride. The dominant mode of sulfometuron adsorption on PC is via strong electrostatic interactions. The proposed interactions of sulfate with PC are outer‐ and inner‐sphere complexation. The pH is reduced with sulfate adsorption and Al is released. The proposed mode of acetate interactions with PC is mainly via inner‐sphere complexation. In this case the pH increases with acetate adsorption, indicating exchange of acetate with surface hydroxyls, and Al is not released.
A Two‐Domain Approach Using CAT Scanning to Model Solute Transport in Soil
Authors: Perret Johan , Prasher S. O. , Kantzas A. , Langford C. 
Published: July 2010

AbstractMulti‐region modeling can be used to simulate dynamics of preferential flow in soils. However, the criteria used to determine boundaries between flow regions have been defined arbitrarily up to now. Therefore, there is a need to develop a reliable technique to isolate and characterize flow domains in soil. The primary objective of this study was to develop a reliable method for isolating and characterizing flow domains in a large undisturbed soil column using a computer assisted tomography (CAT) scanner. This approach allows for real‐time examination of flow mechanisms through soil macropores at various depths along the length of soil columns. With the knowledge of the macropore structure and the spatial distribution of the solute, breakthrough in the macropore and matrix flow domains was evaluated. Flow in the matrix domain suggested that part of the matrix contains small pores that are connected to macropore networks. These pores contribute to a rapid tracer buildup in the matrix domain. The breakthrough curves (BTCs) measured in the matrix domain were fitted using the convection dispersion equation (CDE) with CXTFIT 2.0. The macropore domain was divided into two regions, namely the laminar and turbulent regions. A modified version of Poiseullle's law was used to model solute breakthrough in the laminar region. For the turbulent region, a new formula was derived based on Manning's equation. The modifications were done so that these simple models would take into account the distribution density functions of macropore size and hydraulic radius. This approach provides reliable approximation of the overall breakthrough of solutes in the macropore domain.
Anaerobic Biodegradation of Trichloroethylene Sorbed by a Surrogate Soil Organic Matter
Authors: Sheremata Tamara W. , Yong Raymond N. , Ghoshal Subhasis , Guiot Serge R. 
Published: July 2010

AbstractThe effects of aging trichloroethylene (TCE) with a surrogate soil organic matter (SSOM) on its anaerobic biodegradation and desorption characteristics were studied. Surrogate soil organic matter comprised of composted sphagnum moss was used as a model sorbent, and Desulfomonile tiedjei was used as a model member of an anaerobic consortium capable of reductive dechlorination. After TCE was aged with the sterile SSOM for periods of 2, 14, and 30 d, the completely mixed batch reactors were inoculated with D. tiedjei cells and incubated for 5 d. The mass of TCE dechlorinated to cis‐1,2‐dichloroethylene (DCE) by D. tiedjei in this period decreased by 72% from 2 to 30 d of aging. Although there was an increase in the equilibrium desorption coefficient (Kd) with aging, sorption was completely reversible. Hence, the reduced availability of TCE for degradation was not coupled with irreversible sorption. To examine the longer‐term fate of TCE, the unaged TCE‐SSOM slurries were inoculated with D. tiedjei and then incubated for longer times (15, 24, and 29 d vs. 5 d). The conversion of TCE to cis‐1,2‐DCE was up to eight times greater than what was observed in control experiments without SSOM. Therefore, although aging resulted in reduced TCE biodegradation for short‐term incubation (5 d), longer‐term incubation (29 d) with the unaged SSOM resulted in extensive TCE dechlorination (up to 40%) to cis‐1,2‐DCE.
Predictive Assessment of the Aquatic Toxicity of Multiple Chemical Mixtures
Authors: Faust M. , Altenburger R. , Backhaus T. , Bödeker W. , Scholze M. , Grimme L. H. 
Published: July 2010

AbstractCurrent approaches to the assessment of chemical hazards focus on toxicity studies with single, pure chemicals. In the environment, however, organisms are exposed to numerous pollutants simultaneously. We studied the toxicities of multiple mixtures of pesticides and antibiotics in algal and bacterial bioassays. The test mixtures were composed of 14 to 18 components with either identical or completely different specific mechanisms of action. The results reveal that reliable predictions of mixture toxicities can be derived from concentration response data of single toxicants by applying two different concepts: concentration addition in cases of similarly acting mixture components and independent action for substances with dissimilar mechanisms of action.
Nitrate Leaching as Affected by Introduction or Discontinuation of Cover Crop Use
Authors: Hansen E. M. , Djurhuus J. , Kristensen K. 
Published: July 2010

AbstractA 24‐yr‐old permanent field trial with spring‐sown crops was used in a nitrate N leaching study to determine (i) the effect of long‐term cover crop use compared with the introduction of perennial ryegrass (Lolium perenne L.) as a cover crop on plots with a history of no previous cover crop use and (ii) the effect of discontinuing long‐term use of ryegrass as a cover crop compared with no previous cover crop use. The cover crop (seed rate 8–10 kg ha−1) was undersown in spring wheat (Triticum aestivum L.). The field trial was conducted on a coarse sand (Orthic Haplohumod) under temperate coastal climate conditions in Denmark. From 1993 to 1997, nitrate leaching was estimated by use of soil water samples from ceramic cups in four treatments: cover crop since 1968, cover crop since 1993, no cover crop, and cover crop until 1993. Each treatment was carried out at two N rates: 60 and 120 kg N ha−1 yr−1. As an average of 4 yr and two N rates, leaching was 14 kg N ha−1 yr−1 or 29% higher in plots with long‐term previous cover crop use than in plots without. The effect of previous long‐term use of ryegrass as a cover crop lasted at least 4 yr. Thus, if the higher N mineralization due to long‐term use of cover crop is not taken into consideration by adjusting the cropping system, the reduction in nitrate leaching caused by the cover crop may not be as significant in the long‐term.
Cadmium Availability to Three Plant Species Varying in Cadmium Accumulation Pattern
Authors: Gérard Emilie , Echevarria Guillaume , Sterckeman Thibault , Morel Jean Louis 
Published: July 2010

AbstractPlant response to soil Cd is highly variable. Plants varying in Cd accumulation pattern were evaluated to determine if Cd was taken up from similar or different pools in soils. Three metal‐contaminated soils (pH 8) and noncontaminated soil were labeled with 109Cd using a carrier‐free 109CdCl2 solution. Rye grass (Lolium perenne L.), lettuce (Lactuca sativa L.), and the Zn‐ and Cd‐hyperaccumulator Thlaspi caerulescens J. Presl & C. Presl were grown on these soils and harvested. The isotopic composition of Cd in plant shoots (ICP) was measured and the isotopic composition in the soil solution (ICS) was calculated using the isotopic exchange kinetics (IEK) method. The Cd concentrations in shoots ranged from 0.1 to 2.3 mg kg−1 in rye grass, 0.4 to 8.3 mg kg−1 in lettuce, and 8.7 to 647 mg kg−1 in T. caerulescens. The ICP values were similar among species, suggesting that the same pool of soil isotopically exchangeable Cd was accessed despite variations in Cd uptake pattern. The ICP values were similar to the ICS, suggesting that the IEK method assesses the pool that is phytoavailable. Despite the high soil pH, more than 50% of the total soil Cd was isotopically exchangeable within 90 d. Lettuce and rye grass took up less than 1% of the exchangeable Cd while T. caerulescens extracted up to 22% of this pool. In conclusion, plants representing a wide array of behavior toward Cd take up the metal from a similar pool of soil Cd, which is assessed by the IEK method.
Throughfall Patterns in a Subtropical Rain Forest of Northeastern Taiwan
Authors: Lin Teng‐Chiu , Hamburg Steven P. , King Hen‐Biau , Hsia Yue‐Joe 
Published: July 2010

AbstractThroughfall chemistry of a subtropical rain forest in Taiwan was examined for 3 yr to understand patterns of nutrient inputs to the forests of this region. Annual throughfall fluxes for NH+4, NO−3, and SO2−4 (89, 28, and 83 mmol/m2/yr, respectively) were close to the levels of the most polluted areas in the temperate region. The lack of major emission sources near the study site indicates that most of the pollutants were regional and/or international in origin. High rates of cation leaching from the forest canopy were evident and the pattern is similar to that seen in heavily polluted temperate forests. Typhoons played a central role in the hydrology of the study forest with eight typhoons contributing 26% of the total rainfall in 320 h over the three years monitored. This typhoon input represented 20% of the total precipitation flux of the ions found in seasalt aerosols but less than 10% of anthropogenically enriched ions. Canopy leaching was an important source of base cations in throughfall and NO−3 was retained in the canopy. Using the Na‐ratio method the contribution of dry deposition relative to precipitation input was estimated to be 40% in the summer and 10% in the winter. The contribution of dry deposition to total deposition is small relative to many temperate forests and might result from the lack of long dry periods between precipitation events. Net throughfall flux was negatively related to precipitation concentration for H+, NH+4, NO−3, and SO2−4, suggesting that passive movement was important in characterizing throughfall dynamics.
The Influence of Vegetation in Riparian Filterstrips on Coliform Bacteria: I. Movement and Survival in Water
Authors: Entry James A. , Hubbard Robert K. , Thies Janice E. , Fuhrmann Jeffry J. 
Published: July 2010

AbstractSwine (Sus scrofa) wastewater was applied to three separate 4 m wide × 30 m long riparian filterstrips consisting of 20 m grass and 10 m forest, 10 m grass and 20 m forest, and 10 m grass and 20 m maidencane (Panicum hemitomon Schult.) in Southern Georgia during each season. Total and fecal coliform numbers in the applied wastewater pulse did not decline as water moved downslope regardless of vegetation type or season. The pulse of applied wastewater did not move beyond 15 m in any treatment in autumn or summer (dry seasons) and only moved beyond 7.5 m in the 20 m grass‐10 m forest treatment in the summer. Total and fecal coliform numbers in soil water and shallow ground water declined by approximately 10‐fold every 7 d for the first 14 d regardless of vegetative treatment or season. Soil temperature and soil moisture correlated with total coliform bacteria in both 1.5 m wells (r2 = 0.89) and 2.0 m wells (r2 = 0.89), and with fecal coliform bacteria in 1.5 (r2 = 0.82) and 2.0 m (r2 = 0.76) wells. Animal production operations may need to locate in warm‐dry climates so animal waste can be applied to lands to help ensure enteric bacteria input to surface and ground water will not occur.
Organic Nitrogen in Drainage Water from Grassland in Northern Ireland
Authors: Watson C. J. , Jordan C. , Lennox S. D. , Smith R. V. , Steen R. W. J. 
Published: July 2010

AbstractLoss of organic N in land drainage may contribute to water pollution. This study was conducted to quantify the loss of organic nitrogen in drainage water from grazed grassland (Lolium perenne L. cv. Talbot) swards receiving a range of fertilizer N inputs for 9 yr. Plots (each 0.2 ha) received 100, 200, 300, 400, or 500 kg N ha−1 yr−1 as calcium ammonium nitrate and were hydrologically isolated and drained to V‐notch weirs with automatic sampling of drainage water. For comparison, organic N loss was quantified in rivers draining six predominantly grassland catchments. The European Community maximum admissible concentration of total Kjeldahl N for drinking water of 1.0 mg N L−1 was exceeded in both land drainage and river water. Total organic N accounted for up to 54.7 and 20.2% of the annual N drainage losses from the plots receiving 100 and 500 kg N ha−1 yr−1, respectively. Loads of soluble organic N were greater than particulate N but there was no significant relationship with fertilizer N input for either fraction. The average annual loss of total organic N in drainage water ranged from 3.5 to 9.1 kg N ha−1. However, this loss cannot explain the large amount of unaccounted for N in calculations of nutrient balances where inputs invariably exceed outputs. In comparison, the average annual loss of organic N from the six river catchments ranged from 4.7 to 8.1 kg N ha−1, which suggested that a large proportion of the organic N in river water was originating from land drainage.
Nutrient Losses in Subsurface Drainage Water from Dairy Manure and Urea Applied for Corn
Authors: Randall G. W. , Iragavarapu T. K. , Schmitt M. A. 
Published: July 2010

AbstractLand application of dairy (Bos taurus) manure has generated concern regarding the downward movement of nutrients and pathogens from the manure through the soil profile into subsurface drainage water and ultimately to surface waters. The objective of this study was to determine the effect of dairy manure and urea applied at equivalent rates of “available” N on (i) NO3−N, total phosphorus (TP), ortho‐P, NH3−N, and Escherichia coli losses to subsurface tile drainage; (ii) corn (Zea mays L.) production; and (iii) changes in soil test phosphorus (STP) and soil test potassium (STK). Liquid dairy manure and urea fertilizer were broadcast applied at equivalent total “available” N rates ranging from 154 to 224 kg ha−1 yr−1 each fall during 1993–1996. The soil was a poorly drained Webster clay loam (fine loamy, mixed, superactive, Typic Endoaquoll). Nitrate N, TP, and ortho‐P concentrations and NO3−N losses in the subsurface drainage water were not different between the two N sources. Total P exceeded the minimum detection limit in 40 and 52% of the drainage samples from the urea and manured plots, respectively, while only 22 and 35% of the samples had detectable levels of ortho‐P. Losses of TP and ortho‐P were very small and averaged 31 and 10 g ha−1 yr−1, respectively, from the manured plots or <0.02% of the manure‐P applied. Four‐year average corn yields were 0.7 Mg ha−1 greater for the urea treatment compared with dairy manure. Soil test P and STK in the top 20 cm were increased 1 mg kg−1 for every 12 kg P ha−1 and 10 kg K ha−1 applied as manure. We conclude that dairy manure, when applied at optimal rates and incorporated immediately, does not lead to greater losses of N and P in subsurface drainage water on this fine‐textured soil compared with urea.
Water Selenium Speciation and Sediment Fractionation in a California Flow‐Through Wetland System
Authors: Gao S. , Tanji K. K. , Peters D. W. , Herbel M. J. 
Published: July 2010

AbstractA flow‐through wetland system was established in the Tulare Lake Drainage District (TLDD) in California to determine if selenium (Se) from saline irrigation drainage can be removed prior to impoundment in evaporation basins to reduce potential toxicity to waterbirds. The objective of this research was to evaluate Se speciation, accumulation, and fractionation in the waters and sediments of the newly developed wetland system. The inlet water was dominated by selenate [Se(VI), 92%], with smaller percentages of selenite [Se(IV), 5%] and organic Se [org‐Se(−II), 3%]. For the outflow water, the average percentage of Se(VI) was 72% in November 1997 and 59% in February 1999. This change may be due to an increase in either residence time and/or accumulation of organic detrital matter, which may enhance Se(VI) reduction processes. Selenium accumulation, transformation, and incorporation with the solid phase were all intensified in the surface sediment (<20 cm). The highest total Se concentrations in the sediments were found in the top 5 cm and concentrations dramatically decreased with depth. Elemental Se [Se(0)], as extracted by Na2SO3, was the largest fraction (average of 46%) of the total sediment Se, followed by organic matter‐associated Se (OM‐Se) extracted by NaOH (average of 34%). Soluble, adsorbed, and carbonate‐associated Se, as extracted by KCl, K2HPO4 (pH 8.0), and NaOAc (pH 5.0), were about 3, 10, and 3% of the total sediment Se, respectively. After establishing the wetland for 2 yr, significant Se removal from the flowing water was observed. The major sink mechanisms in the sediment are reduction to Se(0) and immobilization into the organic phase.
Field Investigations and Modeling of Particle‐Facilitated Pesticide Transport in Macroporous Soil
Authors: Villholth Karen G. , Jarvis Nicholas J. , Jacobsen Ole H. , de Jonge Hubert 
Published: July 2010

AbstractPhysical and chemical non‐equilibrium processes may facilitate the transport of pesticides and other chemicals through structured and macroporous soils. For sorbing pesticides, transport associated with a mobile colloidal or particulate phase represents an additional transport mechanismin structured soils that is not well understood. We investigated particle‐facilitated transport of a sorbing pesticide (prochloraz, N‐propyl‐N‐[2‐(2,4,6‐trichlorophenoxy)ethyl]imidazole‐1‐carboxamide) in a 5‐ by 5‐m subsurface‐drained field plot in a structured sandy loam in Denmark. Following pesticide application, three simulated rainfall events during an 8‐d period were monitored in terms of drainage flow rate, content of particulate matter (>0.24 µm), and pesticide concentration in the solution and in the particulate phases in the drainage water. The fraction of pesticide loss to the drain was 0.2% of the applied mass, of which 6% was associated with the particulate phase. Macroporous flow paths appeared to be major routes of pesticide and particle transport. Preferential sorption to particles in the drainage water relative to bulk soil, and possibly also slow desorption from the particles, were assumed to influence the pesticide leaching in the particulate fraction. Based on experimental and reported data, the dual‐porosity model MACRO, modified to account for particle mobilization and transport, could be calibrated to simulate the observations. Sensitive parameters for the particle and pesticide descriptions were identified.
Chemolytic Analysis of Organic Matter during Aerobic and Anaerobic Treatment of Municipal Solid Waste
Authors: Pichler Martin , Kögel‐Knabner Ingrid 
Published: July 2010

AbstractThe aim of our study was to elucidate the mineralization, transformation, and stabilizafion of organic matter (OM) of municipal solid waste (MSW) during four types of aerobic and anaerobic treatment with respect to methane and leachate emissions of treated waste in the landfill. The treatments were (i) windrow composting with and (ii) without pressure aeration, (iii) alternating aerobic and anaerobic treatment in bioreactors, and (iv) anaerobic digestion in a solid‐state fermentation system. The composition of OM was assessed using the following geochemical methods: two‐step acid hydrolysis and colorimetric detection of carbohydrates, colorimetric detection of proteins, CuO oxidation analysis of lignin, and gravimetric determination of lipids. Organic matter losses between 53 and 75% were achieved by all treatments. Carbohydrates are the most relevant compound class for landfill emissions and exhibited the highest mass losses (71 to 88%) during treatment. Hence, a substantial reduction of landfill emission potential was assumed. Protein and lipid losses were lower due to microbial resynthesis and recalcitrance. Lignin was degraded only to a minor extent and experienced no important structural changes. In summary, during the degradation of MSW, the OM composition shifted from easily degradable to recalcitrant compounds, indicating stabilization of MSW. Compared with humified OM of natural topsoil horizons, treated MSW showed slightly higher cellulose and lipid contents. Pressure aeration was essential for achieving optimal degradation rates during aerobic composting. Anaerobic digestion combines high degradation rates and possible energy recovery from methane.