bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing the Origin of Sulfate Deposition at the Hubbard Brook Experimental Forest
Authors: Alewell C. , Mitchell M. J. , Likens G. E. , Krouse R.
Published: July 2010

The geographical and chemical origin of SO2−4 deposition has become a concern, because anthropogenic S emissions have influenced the biogeochemistry of forested ecosystems and surface waters. Our aim was to evaluate the origin of SO2−4 in bulk precipitation at the Hubbard Brook Experimental Forest (HBEF), New Hampshire. We analyzed 26 years of archived bulk precipitation samples for sulfur stable isotopes. We compared the δ34S values with anthropogenic SO2 emissions, the relative contribution of sea salt aerosols (as the SO−4/Na+ ratio in precipitation), and temperature and solar radiation effects on the long‐term patterns of δ34S values. The long‐term pattern of δ34S values in bulk precipitation could be explained partly by the relative contribution of marine SO2−4 or solar radiation but not by temperature variation or anthropogenic SO2 emissions. The high variability of the δ34S values of various fossil fuels makes it difficult to use stable S isotopes for identifying whether changing fossil fuel use is affecting the δ34S values in bulk precipitation. The seasonal pattern of δ34S values in bulk precipitation (significantly higher values in the winter than the summer) may be explained by the temperature dependence of the isotopic shift during SO2−4 formation in the atmosphere. A greater relative contribution of marine SO2−4 during the winter also may have contributed to the higher δ34S values in the winter. Previous investigations may have overestimated the role of biogenic emissions in affecting the δ34S pattern.
Sewage Sludge as an Amendment for Calcareous Bauxite Mine Spoils Reclamation
Authors: Brofas G. , Michopoulos P. , Alifragis D.
Published: July 2010

Dried aerobically digested sewage sludge applied at seven rates (0, 10, 20, 40, 60, 80, and 120 Mg ha−1) in a field experiment on calcareous bauxite mine spoils significantly increased the available water capacity, concentrations of organic matter, total N, extractable P (Olsen), exchangeable Mg2+, and diethylenetriaminepentaacetic acid (DTPA)‐extractable Cu, Mn, Zn, and Pb of mine spoils. Total N and extractable P concentrations decreased with time after sludge application. The DTPA‐extractable Cu concentration was high 4 yr after application at sludge rates of 80 and 120 Mg ha−1. Extractable Cu and Zn concentrations correlated significantly and positively with Cu and Zn concentrations in burnet (Sanguisorba minor subsp. minor) and fiddleneck (Phacelia tanacetifolia Benth) tissue. Sludge application depressed plant Mn uptake. Plant biomass, plant density, and foliar cover significantly increased with treatment rates in the first and fourth growing seasons but decreased with time. Fiddleneck and burnet were the species favored by the high rates of sludge application.
Predicting Subsurface Drainage, Corn Yield, and Nitrate Nitrogen Losses with DRAINMOD‐N
Authors: Zhao S. L. , Gupta S. C. , Huggins D. R. , Moncrief J. F.
Published: July 2010

Nitrate N from artificially drained soils of the upper Midwest USA is finding its way to the Mississippi River and then to the Gulf of Mexico. There is some concern that this nitrate N is causing hypoxia in the Gulf of Mexico. The DRAINMOD‐N model was used to evaluate the long‐term effect of N application rate and drain spacing on corn (Zea mays L.) yield and nitrate N losses. Prior to evaluation, the model was calibrated and then validated against long‐term field data from southwestern Minnesota. A 24‐yr simulation showed that climate plays a major role in determining drainage, yield, and nitrate N losses from a moderately well‐drained Normania clay loam (fine‐loamy, mixed, mesic Aquic Hapludoll) soil under continuous corn. April to August rainfall accounted for 82% of the variation in drainage and 66% of the variation in nitrate N losses during the growing season. Corn yield increased significantly when drain spacing was changed from 56 to 28 m but there was much less increase when changing from 28 to 14 m. During the growing season, drain spacing had little effect on nitrate N losses from this soil. Cost‐benefit analysis showed that a 28 m drain spacing was a good design criterion for this soil. For a given drain spacing, an increase in N application rate significantly increased nitrate N losses through drainage. We conclude that efforts to reduce drainage‐associated nitrate N losses from soils with perched water table conditions in the upper Midwest USA should concentrate on identifying N management strategies that increase N use efficiency.
Molybdenum Uptake by Forage Crops Grown on Sewage Sludge‐Amended Soils in the Field and Greenhouse
Authors: McBride M. B. , Richards B. K. , Steenhuis T. , Spiers G.
Published: July 2010

Molybdenum (Mo) is a plant‐available element in soils that can adversely affect the health of farm animals. There is a need for more information on its uptake into forage crops from waste materials, such as sewage sludge, applied to agricultural land. Field and greenhouse experiments with several crops grown on long‐term sewage sludge‐amended soils as well as soils recently amended with dewatered (DW) and alkaline‐stabilized (ALK) sludges indicated that Mo supplied from sludge is readily taken up by legumes in particular. Excessive uptake into red clover (Trifolium pratense L.) (>30 mg/kg) was seen in a soil that had been heavily amended with sewage sludge 20 yr earlier, where the soil contained about 3 mg Mo/kg soil, three times the background soil concentration. The greenhouse and field studies indicated that Mo can have a long residual availability in sludge‐amended soils. The effect of sludge application was to decrease Cu to Mo ratios in legume forages, canola (Brassica napus var. napus) and soybeans [Glycine max (L.) Merr.] below the recommended limit of 2:1 for ruminant diets, a consequence of high bioavailability of Mo and low uptake of Cu added in sludge. Molybdenum uptake coefficients (UCs) for ALK sludge were higher than for DW sludge, presumably due to the greater solubility of Mo measured in the more alkaline sludges and soils. Based on these UCs, it is tentatively recommended that cumulative Mo loadings on forages grown on nonacid soils should not exceed 1.0 kg/ha from ALK sludge or 4.0 kg/ha from DW sludge.
Desorption of Polycyclic Aromatic Hydrocarbons from Soil in the Presence of Dissolved Organic Matter: Effect of Solution Composition and Aging
Authors: Kögel‐Knabner Ingrid , Totsche Kai U. , Raber Bernd
Published: July 2010

The effect of dissolved organic matter (DOM) on the desorption of polycyclic aromatic hydrocarbons (PAHs) from soil was studied with 14C‐benzo[a]pyrene and 14C‐pyrene in different soil‐aqueous solution systems and after prolonged periods of aging (110 and 216 d). The desorption of 14C‐benzo[a]pyrene and 14C‐pyrene was strongly affected by the composition and properties of the aqueous phase. Desorption linearly increased with increasing DOM concentrations. Distribution coefficients (log Koc′) for the desorption of 14C‐labeled PAHs were about 3.5 (pyrene) and 25 (benzo[a]pyrene) times lower in the presence of DOM. The enhancement of PAH desorption between various types of DOM is controlled by the molecular weight distribution of DOM. Dissolved organic matter with a high proportion of high molecular weight components (>14 000 dalton) has a high affinity for PAHs and thus is more effective in desorbing PAHs from soil. In addition, the desorption of PAHs from soil is controlled by the time elapsed since contamination. In the first 36 d following contamination with 14C‐benzo[a]pyrene, a decrease of the PAH concentration that could be desorbed in the solution phase was observed. The desorbable fraction did not show any further changes for up to 183 d after contamination, suggesting a fraction of PAH that is not or very slowly desorbing from soil. The major proportion (>98%) of the desorbable PAH‐fraction is apparently bound at sites that show a rate‐limited release of PAHs. This is corroborated by the model discrimination conducted with three different models, which favors a two‐site equilibrium‐nonequilibrium model.
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

The 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

The 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

Multi‐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

The 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

Current 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

A 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

Plant 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

Throughfall 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

Swine (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

Loss 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

Land 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

A 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

Physical 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

The 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.
Gaseous Nitrogen Emissions from Anaerobic Swine Lagoons: Ammonia, Nitrous Oxide, and Dinitrogen Gas
Authors: Harper Lowry A. , Sharpe Ron R. , Parkin Tim B.
Published: July 2010

Seventy‐five percent of swine (Sus scrofa) production systems in North America use anaerobic or liquid‐slurry systems for waste holding or disposal. Accurate emissions data and emission factors are needed for engineering, planning, and regulatory agencies. These data are used for system design and evaluation of the effect of animal concentrations on the regional soil, surface and ground waters, and atmospheric environments. Noninvasive techniques were used to evaluate trace gases without disturbing the meteorology or lagoon system being measured. Micrometeorological and gas sensors were mounted on a submersible barge in the center of the lagoon for use with flux‐gradient methodology to determine trace gas fluxes, without disturbing atmospheric transport processes, over extended periods. Collateral measurements included lagoon nutrient, dissolved gas concentrations, and sludge gas mass flux. Ammonia emissions varied diurnally and seasonally and were highly correlated with windspeed and water temperature. Nutrient loading measurements showed that mobile ions, which were nonvolatile, were constant throughout four successive lagoons. Immobile ions concentrated primarily in the sludge layer of the first lagoon. Measurements of denitrification N2 losses suggest as much N2−N lost as from NH3‐N. Ammonia gas emissions are not as large a percentage of total nitrogen input to the lagoons as previously thought but unaccounted‐for nitrogen requires further research.
Simulation of Pesticide Persistence in the Field on the Basis of Laboratory Data—A Review
Authors: Beulke Sabine , Dubus Igor G. , Brown Colin D. , Gottesbüren Bernhard
Published: July 2010

Simulations of pesticide fate in soils are often based on persistence models developed nearly 30 years ago. These models predict dissipation in the field on a daily basis by correcting laboratory degradation half‐lives for actual soil temperature and moisture content. They have been extensively applied, but to date no attempt has been made to evaluate existing studies in a consistent, quantitative way. This paper reviews 178 studies comparing pesticide soil residues measured in the field with those simulated by persistence models. The simulated percentage of initial pesticide concentration at the time of 50% measured loss was taken as a common criterion for model performance. The models showed an overall tendency to overestimate persistence. Simulated values ranged from 12 to 96% of initial pesticide concentrations with a median of 60%. Simulated soil residues overestimated the target value (50% of initial) by more than a factor of 1.25 in 44% of the cases. An underestimation by more than a factor of 1.25 was found in only 17% of the experiments. Discrepancies between simulated and observed data are attributed to difficulties in characterizing pesticide behavior under outdoor conditions using laboratory studies. These arise because of differences in soil conditions between the laboratory and the field and the spatial and temporal variability of degradation. Other possible causes include losses in the field by processes other than degradation, deviations of degradation from first‐order kinetics, discrepancies between simulated and actual soil temperature and moisture content, and the lack of soil‐specific degradation parameters. Implications for modeling of pesticide behavior within regulatory risk assessments are discussed.
Response of Four Turfgrass Cultivars to Limestone and Biosolids‐Compost Amendment of a Zinc and Cadmium Contaminated Soil at Palmerton, Pennsylvania
Authors: Li Yin‐Ming , Chaney Rufus L. , Siebielec Grzegorz , Kerschner Beverly A.
Published: July 2010

Revegetation treatments (NPK fertilizer, limestone plus NPK fertilizer, or composted iron‐rich limed biosolids) were evaluated on severely Zn phytotoxic soils near a former smelter. Soils contained 15 500 mg Zn and 158 mg Cd kg−1 and initial soil pH was 6.0. Zinc‐resistant ‘Merlin’ red fescue (Festuca rubra L.) was compared with ‘Bonanza’ and ‘Kentucky‐31’ tall fescue (Festuca arundinacea Schreb.) and ‘Touchdown’ Kentucky bluegrass (Poa pratensis L.) for leaf phytotoxicity symptoms, rapidity of achieving cover, persistence of cover, and metal accumulation. Biosolids compost more strongly reduced soluble Zn and Cd, resulting in effective remediation of Zn phytotoxicity that persisted for the 4 yr of this test. ‘Merlin’ red fescue showed remarkable exclusion of Zn and Cd (201–446 mg kg−1 Zn and 0.9–2.7 mg kg−1 Cd in dry shoots from treated plots) but grew slowly and made poor lawns. ‘Kentucky‐31’ tall fescue plants grew rapidly and reached almost 100% cover within 3 mo in compost treatment plots, but the Zn exceeded phytotoxic threshold levels (>500 mg Zn kg−1). ‘Bonanza’ tall fescue and ‘Touchdown’ Kentucky bluegrass had good growth performance and contained lower concentrations of Zn and Cd than ‘Kentucky‐31’ tall fescue on biosolids‐compost amended treatments and were more suitable as a lawn and/or revegetation crop. After the first year of the study, the commercial turfgrasses survived only on the biosolids‐compost plots. The combination of calcareous soil pH and higher organic matter, Fe, and phosphate levels of biosolids‐compost amended plots improved the overall success of vegetation establishment and allowed important turfgrasses to revegetate highly Zn‐contaminated soils.
Phosphorus Forms in Manure and Compost and Their Release during Simulated Rainfall
Authors: Sharpley Andrew , Moyer Barton
Published: July 2010

The large accumulation of P in manure from animal feeding operations in localized areas has increased the potential for P export following land application. Impairment of freshwater quality by accelerated eutrophication has focused attention on manure management and the potential for P loss in runoff. Thus, we investigated the amounts and relative solubilities of P in manures and their composts using a modified Hedley fractionation and release of P during simulated rainfall (70 mm h−1 for 30 min) in laboratory columns (15‐cm diameter). Twenty‐four samples each of dairy manure, dairy manure compost, poultry manure, poultry manure compost, poultry litter, and swine manure were collected over 2 yr. Total P concentration ranged from 2600 to 40 000 mg kg−1, mostly as inorganic P (63 to 92%). The distribution of inorganic and organic P fractions depended on manure and compost type. Most of the inorganic P, 80%, was water extractable (2030 mg kg−1), while 55% was hydroxide extractable in swine slurry (16 620 mg kg−1) and 38% acid extractable in poultry manure (9320 mg kg−1). The dissolved inorganic P concentration in leachate from manure and compost (10 Mg ha−1 manure application rate) during 30‐rain rainfall ranged from 34 (poultry litter) to 75 mg L−1 (poultry manure). The amount of P leached by five simulated rainfall events was significantly correlated to respective water extractable inorganic (r2 = 0.98) or organic P (r2 = 0.99) of each material. This suggests that water extractable P may be used to estimate the potential for land‐applied manures or composts to enrich leachate and surface runoff P.
Evaluation of an Organic Semiconductor as a Sensor of Volatilized Herbicides
Authors: Álvarez‐Benedí J. , Souto J. , De Saja J. A. , Bolado S.
Published: July 2010

The use of a ytterbium bisphthalocyanine Langmuir‐Blodgett film sensor for the study of the volatilization of the herbicides imazamethabenz‐methyl, tri‐allate, and terbutryn is evaluated. The dynamic response of the sensor to the herbicides is analyzed using a model that relates the response of an isotropic sensor to the total immobilized amount of a particular herbicide, accounting for the diffusion through the sensor and the adsorption of each herbicide in the sensor's film. Three model parameters are analyzed in the response of the sensor to a pulse in the concentration of herbicide, analyzing separately the sorption and desorption stages: the response time (τ), the adsorption isotherm linearity (1/n), and the linearity of the variation of the electrical conductivity of the sensor with the amount of sorbed herbicide (B). In the sorption stage, τ ranged from 174 to 341 s, 1/n ranged from 0.57 to 1.04, and B was within the interval from 1.54 to 2.4. The desorption stage required a longer time to be accomplished and thus is less useful for practical purposes. The model parameters are compared with semiqualitative analysis of the response curves in the sorption stage and the capabilities of these sensors in qualitative and quantitative analysis of volatilized herbicides are discussed. Based on the differences in the model parameters, the sensors offered promising results for identification purposes. The results also suggest applications in quantitative analysis, although further improvements in the methodology are required for that purpose.
Pesticide Sorption by Low Organic Carbon Sediments: A Screening for Seven Herbicides
Authors: Madsen Lene , Lindhardt Bo , Rosenberg Per , Clausen Liselotte , Fabricius Ida
Published: July 2010

The sorption of seven pesticides in 10 Danish aquifer sediments has been studied. These sediments all have a total organic carbon (TOC) content below 1 g kg−1, and include carbonate‐bearing and carbonate‐free Quatenary sand deposits and a Cretaceous chalk aquifer. Batch experiments were carried out with metamitron, atrazine, isoproturon, mecoprop, 2,4‐D, bentazone, and metsulfuron‐methyl at an initial pesticide concentration of 0.25 mg L−1 in ground water. Generally, the sorption decreases in the order: metamitron, atrazine, isoproturon, mecoprop, 2,4‐D, metsulfuron‐methyl. The bentazone sorption was found to be insignificant. For a specific pesticide the sorption covers a range of Kd values (L kg−1) reflecting the different sediment characteristics. Multivariate regression analyses demonstrate that: (i) metamitron sorption is enhanced by increasing content of iron silicates; by contrast the oxalate extractable iron oxides have no influence on the metamitron sorption; (ii) sorption of atrazine, mecoprop, and 2,4‐D depends primarily on pH; the sorption is high at low pH (<6.7) compared with sorption at higher pH (>7.4); (iii) metsulfuron‐methyl only sorbs at pH below 5; and (iv) isoproturon sorption is primarily influenced by the specific surface area (SSA) and TOC. The present results illustrate the importance of choosing sediments of different geological origin in order to describe the influence of sediment properties on pesticide sorption.
Integrated Fertilizer and Irrigation Management to Reduce Nitrate Leaching in Central Spain
Authors: Diez J. A. , Caballero R. , Roman R. , Tarquis A. , Cartagena M. C. , Vallejo A.
Published: July 2010

Cropping systems that fail to manage N and irrigation, with the objective of reducing losses of N, are frequently associated with elevated concentrations of nitrate N in soil and ground water. A long‐term (4‐yr) field experiment was carried out at La Poveda Field Station (30 km southeast of Madrid, Spain) with the objective of assessing whether the effect of traditional cultivation practices (irrigation and fertilization) can be reduced. The experiment was conducted on a Typic Xerofluvent soil and a crop sequence (corn‐wheat‐corn‐oat) traditional in the area. Four fertilizer treatments (unfertilized check, urea, floranid [a slow‐release N fertilizer] and municipal organic waste [MOW] compost) were combined with two irrigation schedules (traditional and improved) in two sets of 24 plots. Seasonal drainage was estimated by the zero flux plane‐water balance equation and nitrate concentration was measured at the soil depth of deep percolation (1.4 m) by ceramic cup extraction system. Nitrate leaching could be attributed to both irrigation schedule and fertilizer type. Within fertilizer treatments, reductions of nitrate losses between irrigation schedules of 52, 51, 66, and 81% were found for the unfertilized check, urea, floranid, and MOW compost, respectively. Grain yields in the whole crop sequence were not affected by fertilizer or irrigation managements.
Herbicide Banding and Tillage Effects on Runoff, Sediment, and Phosphorus Losses
Authors: Hansen N. C. , Gupta S. C. , Moncrief J. F.
Published: July 2010

Tillage and weed control methods affect hydrology by altering soil surface conditions. The objective of this study was to assess the effects of herbicide banding with interrow cultivation on runoff, sediment, and phosphorus (P) losses for three different tillage systems. Tillage treatments were moldboard‐ or chisel plow‐based and ridge tillage. Tillage direction was up and down the slope of runoff plots and corn (Zea mays L.) was grown for two years. The herbicides alachlor [2‐chloro‐2′‐6′‐diethyl‐N‐(methoxymethyl)‐acetanilide] and cyanazine [2‐[ [4‐chloro‐6‐(ethylamino)‐1,3,5‐triazin‐2‐yl]amino‐2‐methylproprionitrile] were applied as a preemergent mixture by either broadcasting or banding. All treatments were mechanically cultivated one time. The effects of tillage practice and herbicide application method on runoff water quality were different before and after cultivation. Prior to cultivation, crop residue associated with the ridge till and chisel plow systems reduced runoff, sediment, and P losses compared with the moldboard plow system. Soil cover from weed growth between herbicide treated bands resulted in lower precultivation runoff, sediment, and P losses than broadcast treated plots, especially in the moldboard plow system. For runoff events occurring after cultivation, there were no differences among tillage practices or herbicide application methods on sediment or P losses. Weed cover between herbicide treated bands is effective in reducing runoff and contaminant losses in tillage systems with little existing crop residue and during the period when crop canopy is minimal. There was no yield loss associated with applying herbicides in a band compared with broadcasting.
An Agri‐Environmental Phosphorus Saturation Index for Acid Coarse‐Textured Soils
Authors: Khiari L. , Parent L. E. , Pellerin A. , Alimi A. R. A. , Tremblay C. , Simard R. R. , Fortin J.
Published: July 2010

Potato (Solanum tuberosum L.) is a high P demanding crop contributing to P saturation of acid coarse‐textured soils. The P status is commonly assessed agronomically by soil testing of P (STP) and environmentally by soil P saturation or P solubility indexes. The aim of this work was to develop a P fertilizer recommendation model integrating P environmental risk and crop response probability, using P and Al extracted by the Mehlich‐III soil testing method (mg P or Al L−1 of soil) and expressed as (P/Al)M‐III percentage. The environmentally critical (P/Al)M‐III percentage was 15%, corresponding to the critical degree of phosphate saturation (DPS) value of 25% (oxalate extraction procedure) proposed in the Netherlands. Using the Cate‐Nelson procedure, the critical (P/Al)M‐III percentage across 78 field experiments was 8.2% as determined by inductively coupled‐argon plasma (ICP). Probability of potato response to P was close to 100% even above the critical STP values as shown by power tests on relative yields. The P recommendation model was computed from conditional expectations of 50 and 80% within each fertility group below 15% as (P/Al)M‐III. Above 15%, the model recommended 21 kg P ha−1, the amount of P exported by a tuber harvest of approximately 42 Mg ha−1. Using conversion equations with 114 soil samples for STP methods, fertility groups built for Quebec acid coarse‐textured soils were found to be comparable with those currently used in the Netherlands and Lower Saxony (Germany). The (P/Al)M‐III percentage provided a reliable and unifying criterion for making environmentally acceptable and agronomically efficient P recommendations for sustainable potato production.