bluuebunny/crossref_metadata_2025_split huggingface dataset:
Irrigated Mountain Meadow Fertilizer Application Timing Effects on Overland Flow Water Quality
Authors: White Shawn K. , Brummer Joe E. , Leininger Wayne C. , Frasier Gary W. , Waskom Reagan M. , Bauder Troy A. 
Published: June 2010

ABSTRACTNonpoint‐source pollution from agricultural activities is currently the leading cause of degradation of waterways in the United States. Applying best management practices to flood‐irrigated mountain meadows may improve agricultural runoff and return flow water quality. Prior research has focused on fertilizer use for increased hay yields, while few studies have investigated the environmental implications of this practice. We examined the effects of fertilizer application timing on overland flow water quality from an irrigated mountain meadow near Gunnison, Colorado. Application of 40 kg phosphorus (P) and 19 kg nitrogen (N) ha−1 using monoammonium phosphate (11–52–0, N–P–K) fertilizer to plots in the fall significantly reduced concentrations of reactive P and ammonium N in irrigation overland flow compared with early or late spring fertilization. Reactive P loading was 9 to almost 16 times greater when fertilizer was applied in the early or late spring, respectively, compared with in the fall. Ammonium N followed a similar trend with early spring loading more than 18 times greater and late spring loading more than 34 times greater than loads from fall‐fertilized plots. Losses of 45% of the applied P and more than 17% of the N were measured in runoff when fertilizer was applied in the late spring. These results, coupled with those from previous studies, suggest that mountain meadow hay producers should apply fertilizer in the fall, especially P‐based fertilizers, to improve hay yields, avoid economic losses from loss of applied fertilizers, and reduce the potential for impacts to water quality.
Speciation of Phosphorus in Phosphorus‐Enriched Agricultural Soils Using X‐Ray Absorption Near‐Edge Structure Spectroscopy and Chemical Fractionation
Authors: Beauchemin Suzanne , Hesterberg Dean , Chou Jeff , Beauchemin Mario , Simard Régis R. , Sayers Dale E. 
Published: June 2010

ABSTRACTKnowledge of phosphorus (P) species in P‐rich soils is useful for assessing P mobility and potential transfer to ground water and surface waters. Soil P was studied using synchrotron X‐ray absorption near‐edge structure (XANES) spectroscopy (a nondestructive chemical‐speciation technique) and sequential chemical fractionation. The objective was to determine the chemical speciation of P in long‐term‐fertilized, P‐rich soils differing in pH, clay, and organic matter contents. Samples of three slightly acidic (pH 5.5–6.2) and two slightly alkaline (pH 7.4–7.6) soils were collected from A or B horizons in two distinct agrosystems in the province of Québec, Canada. The soils contained between 800 and 2100 mg total P kg−1 Distinct XANES features for Ca‐phosphate mineral standards and for standards of adsorbed phosphate made it possible to differentiate these forms of P in the soil samples. The XANES results indicated that phosphate adsorbed on Fe‐ or Al‐oxide minerals was present in all soils, with a higher proportion in acidic than in slightly alkaline samples. Calcium phosphate also occurred in all soils, regardless of pH. In agreement with chemical fractionation results, XANES data showed that Ca‐phosphates were the dominant P forms in one acidic (pH 5.5) and in the two slightly alkaline (pH 7.4–7.6) soil samples. X‐ray absorption near‐edge structure spectroscopy directly identified certain forms of soil P, while chemical fractionation provided indirect supporting data and gave insights on additional forms of P such as organic pools that were not accounted for by the XANES analyses.
On‐Farm Assessment of Biosolids Effects on Soil and Crop Tissue Quality
Authors: Shober Amy L. , Stehouwer Richard C. , Macneal Kirsten E. 
Published: June 2010

ABSTRACTAgronomic use of biosolids as a fertilizer material remains controversial in part due to public concerns regarding the potential pollution of soils, crop tissue, and ground water by excess nutrients and trace elements in biosolids. This study was designed to assess the effects of long‐term commercial‐scale application of biosolids on soils and crop tissue sampled from 18 production farms throughout Pennsylvania. Biosolids application rates ranged from 5 to 159 Mg ha−1 on a dry weight basis. Soil cores and crop tissue samples from corn (Zea mays L.), soybean (Glycine spp.), alfalfa (Medicago sativa L.), orchardgrass (Dactylis spp.) hay, and/or sorghum [Sorghum bicolor (L.) Moench] were collected for three years from georeferenced locations at each farm. Samples were tested for nutrients, trace elements, and other variables. Biosolids‐treated fields had more post–growing season soil NO3 and Ca and less soil K than control fields and there was some evidence that soil P concentrations were higher in treated fields. The soil concentrations of Cu, Cr, Hg, Mo, Mn, Pb, and Zn were higher in biosolids‐treated fields than in control fields; however, differences were ≤0.06 of the USEPA Part 503 cumulative pollutant loading rates (CPLRs). There were no differences in the concentrations of measured nutrients or trace elements in the crop tissue grown on treated or control fields at any time during the study. Commercial‐scale biosolids application resulted in soil trace element increases that were in line with expected increases based on estimated trace element loading. Excess NO3 and apparent P buildup indicates a need to reassess biosolids nutrient management practices.
Particulates, Not Plants, Dominate Nitrogen Processing in a Septage‐Treating Aerated Pond System
Authors: Hamersley M. Robert , Howes Brian L. , White David S. 
Published: June 2010

ABSTRACTIn pond and wetland systems for wastewater treatment, plants are often thought to enhance the removal of ammonium and nitrogen through the activities of root‐associated bacteria. In this study, we examined the role of plant roots in an aerated pond system with floating plants designed to treat high‐strength septage wastewater. We performed both laboratory and full‐scale experiments to test the effect of different plant root to septage ratios on nitrification and denitrification, and measured the abundances of nitrifying bacteria associated with roots and septage particulates. Root‐associated nitrifying bacteria did not play a significant role in ammonium and total nitrogen removal. Investigations of nitrifier populations showed that only 10% were associated with water hyacinth [Eichhornia crassipes (Mart.) Solms] roots (at standard facility plant densities equivalent to 2.2 wet g roots L−1 septage); instead, nitrifiers were found almost entirely (90%) associated with suspended septage particulates. The role of root‐associated nitrifiers in nitrification was examined in laboratory batch experiments where high plant root concentrations (7.4 wet g L−1, representing a 38% net increase in total nitrifier populations over plant‐free controls) yielded a corresponding increase (55%) in the non‐substrate‐limited nitrification rate (Vmax). However, within the full‐scale septage‐treating pond system, nitrification and denitrification rates remained unchanged when plant root concentrations were increased to 7.1 g roots L−1 (achieved by increasing the surface area available for plants while maintaining the same tank volume). Under normal facility operating conditions, nitrification was limited by ammonium concentration, not nitrifier availability. Maximizing plant root concentrations was found to be an inefficient mechanism for increasing nitrification in organic particulate‐rich wastewaters such as septage.
Corer–Reactors for Contaminant Flux Measurement in Sediments
Authors: Jung R. F. , Jones D. R. , Batley G. E. 
Published: June 2010

ABSTRACTDesign details and operating instructions are provided for a sediment corer that can be converted into a reactor for the measurement of the fluxes of contaminants from sediments to overlying waters. The corer–reactor permits measurements, under controlled laboratory conditions, on intact, largely undisturbed sediment cores, without significantly perturbing the physical and chemical conditions found in the field. The design can be constructed in‐house for around US$240 (A$400) (excluding motor and corer lid), making it a relatively inexpensive system.
The Effect of Five Forage Species on Transport and Transformation of Atrazine and Isoxaflutole (Balance) in Lysimeter Leachate
Authors: Lin C. H. , Lerch R. N. , Garrett H. E. , Johnson W. G. , Jordan D. , George M. F. 
Published: June 2010

ABSTRACTA field lysimeter study with bare ground and five different ground covers was established to evaluate the effect of forage grasses on the fate and transport of two herbicides in leachate. The herbicides were atrazine (ATR; 2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine) and isoxaflutole [IXF; 5‐cyclopropyl‐4‐(2‐methylsulfonyl‐4‐trifluormethyl‐benzoyl)isoxazole], which has the commercial name Balance (Aventis Crop Science, Strasbourg, France). The ground covers included orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue (Festuca arundinacea Schreb.), timothy (Phleum pratense L.), and switchgrass (Panicum virgatum L.). The results suggested that the total IXF (parent + metabolites) showed higher mobility than ATR and its metabolites. Differences in the timing of transport reflected the rapid degradation of IXF to the more soluble, stable, and biologically active diketonitrile (DKN) metabolite in the system. Although grass treatments did not promote the hydrolysis of DKN, they significantly reduced its transport in the leachate through enhanced evapotranspiration. Grass treatments significantly enhanced ATR degradation in the leachates and soils, especially through N dealkylation, but they did not reduce total ATR transported in the leachate. Leachate from the orchardgrass lysimeters contained the highest proportion of ATR metabolites (64.2%). Timothy and smooth bromegrass treatments also displayed a significant increase in ATR metabolites in leachate. Grass‐treated lysimeters showed higher microbial biomass carbon than bare ground. For ATR treatments, the proportion of metabolites in the leachate strongly correlated with the elevated soil microbial biomass carbon in forage treatments. In contrast, DKN degradation was poorly correlated with soil microbial biomass carbon, suggesting that DKN degradation is an abiotic process.
Role of Mycorrhizal Fungi and Phosphorus in the Arsenic Tolerance of Basin Wildrye
Authors: Knudson J. A. , Meikle T. , DeLuca T. H. 
Published: June 2010

ABSTRACTRevegetation of arsenic (As)‐rich mine spoils is often impeded by the lack of plant species tolerant of high As concentrations and low nutrient availability. Basin wildrye [Leymus cinereus (Scribner & Merr.) A. Löve] has been observed to establish naturally in soils with elevated As content and thus may be useful for the stabilization of As‐contaminated soils. An experiment was conducted to evaluate how variable phosphorus (P) concentrations and inoculation with site‐specific arbuscular mycorrhizal fungi influence As tolerance of basin wildrye. Basin wildrye was grown in sterile sand in the greenhouse for 16 weeks. Pots of sterile sand were amended to create one of four rates of As (0, 3, 15, or 50 mg As kg−1), two rates of P (3 or 15 mg P kg−1), and ±mycorrhizal inoculation in a 2 × 4 × 2 factorial arrangement. After 16 weeks of growth, plants were harvested, shoots and roots thoroughly washed, and the tissue analyzed for total shoot biomass, total root and shoot As and P concentrations, and degree of mycorrhizal infection. Basin wildrye was found to be tolerant of high As concentrations allowing for vigorous plant growth at application levels of 3 or 15 mg As kg−1 Arsenic was sequestered in the roots, with 30 to 50 times more As in the roots than shoots under low P conditions. Mycorrhizal infection did not confer As tolerance in basin wildrye nor did mycorrhizal fungi influence biomass production. Phosphorus concentrations of 15 mg kg−1 effectively inhibited As accumulation in basin wildrye. Basin wildrye has the potential to be used for stabilization of As‐rich soils while minimizing exposure to grazing animals following reclamation.
Light‐Catalyzed Chromium(VI) Reduction by Organic Compounds and Soil Minerals
Authors: Tzou Y. M. , Loeppert R. H. , Wang M. K. 
Published: June 2010

ABSTRACTDetoxification of Cr(VI) through reduction has been considered an effective method for reclaiming Cr‐contaminated soil, sediment, and waste water. Organic matter is widely distributed in soil and aquatic systems; however, low Cr(VI) reduction rates inhibit the adoption of Cr reduction technologies by industry. Scientists have been aware of Cr(VI) reduction catalyzed by soil minerals; however, most of the studies focused on using semiconductors as catalysts with UV irradiation to accelerate the redox reactions. The objective of this study was to evaluate the rates of Cr(VI) reduction by fluorescence light in the presence of organic materials with or without specific soil minerals. Experimental results showed that dissolved organic compounds reduced Cr(VI) slowly under laboratory light; however, Cr(VI) reduction was greatly enhanced when growth chamber light was applied. Low photon flux (i.e., laboratory light) only enhanced Cr(VI) reduction by organics when Fe(III) was also present, because the Fe(II)–Fe(III) redox couple accelerated electron transfer and decreased electrostatic repulsion between reactants. Laboratory light was required to initiate Cr(VI) reduction catalyzed by TiO2; nonetheless, light‐catalyzed Cr(VI) reduction by smectite and ferrihydrite could occur only when greater light energy was provided with a growth chamber light. Our results suggest a potential pathway for Cr(VI) reduction using naturally occurring organic compounds and colloids in acidic water systems or in surface soils when light is available.
Compartmentalization of Metals within the Diverse Colloidal Matrices Comprising Activated Sludge Microbial Flocs
Authors: Leppard Gary G. , Droppo Ian G. , West M. Marcia , Liss Steven N. 
Published: June 2010

ABSTRACTActivated sludge floc from a wastewater treatment system was characterized, with regard to principal structural, chemical, and microbiological components and properties, in relation to contaminant–colloid associations and settling. Multiscale analytical microscopies, in conjunction with multimethod sample preparations, were used correlatively to characterize diverse colloidal matrices within microbial floc. Transmission electron microscopy, in conjunction with energy dispersive spectroscopy (EDS), revealed specific associations of contaminant heavy metals with individual bacterial cells and with extracellular polymeric substances (EPS). Floc structure was mapped from the level of gross morphology down to the nano‐scale, and flocs were described with respect to settling properties, size, shape, density, porosity, bound water content, and EPS chemical composition; gross surface properties were also measured for correlation with principal floc features. Compartmentalization results based on 171 EDS analyses and representative high‐resolution images showed that nano‐scale agglomerations of (i) silver (100%) and (ii) zinc (91%) were confined almost entirely to EPS matrices while (iii) Pb (100%) was confined to intracellular granules and (iv) aluminum was partitioned between EPS matrices (41%) and intracellular matrices (59%). The results suggest that engineered changes in microbial physiology and/or in macromolecular EPS composition may influence metal removal efficiencies.
Major and Trace Elements of Selected Pedons in the USA
Authors: Burt R. , Wilson M. A. , Mays M. D. , Lee C. W. 
Published: June 2010

ABSTRACTFew studies of soil geochemistry over large geographic areas exist, especially studies encompassing data from major pedogenic horizons that evaluate both native concentrations of elements and anthropogenically contaminated soils. In this study, pedons (n = 486) were analyzed for trace (Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn) and major (Al, Ca, Fe, K, Mg, Na, P, Si, Ti, Zr) elements, as well as other soil properties. The objectives were to (i) determine the concentration range of selected elements in a variety of U.S. soils with and without known anthropogenic additions, (ii) illustrate the association of elemental source and content by assessing trace elemental content for several selected pedons, and (iii) evaluate relationships among and between elements and other soil properties. Trace element concentrations in the non‐anthropogenic dataset (NAD) were in the order Mn > (Zn, Cr, Ni, Cu) > (Pb, Co) > (Cd, Hg), with greatest mean total concentrations for the Andisol order. Geometric means by horizon indicate that trace elements are concentrated in surface and/or B horizons over C horizons. Median values for trace elements are significantly higher in surface horizons of the anthropogenic dataset (AD) over the NAD. Total Al, Fe, cation exchange capacity (CEC), organic C, pH, and clay exhibit significant correlations (0.56, 0.74, 0.50, 0.31, 0.16, and 0.30, respectively) with total trace element concentrations of all horizons of the NAD. Manganese shows the best inter‐element correlation (0.33) with these associated total concentrations. Total Fe has one of the strongest relationships, explaining 55 and 30% of the variation in total trace element concentrations for all horizons in the NAD and AD, respectively.
Soil Phosphorus, Management Practices, and Their Relationship to Phosphorus Delivery in the Iowa Clear Lake Agricultural Watershed
Authors: Klatt J. G. , Mallarino A. P. , Downing J. A. , Kopaska J. A. , Wittry D. J. 
Published: June 2010

ABSTRACTClear Lake is on Iowa's list of impaired water bodies because of high P concentration. This study assessed soil‐test phosphorus (STP), management practices, and P loads from its agricultural watershed. Management practice histories and STP for eight basins were surveyed in 1999. Soil samples (15‐cm depth) were analyzed for STP with agronomic [Bray P1 (BP), Olsen (OP), Mehlich 3 (M3P)] and environmental [iron oxide–impregnated paper (FeP) and water extraction (WP)] tests. Total phosphorus (TP) concentrations in water discharge from five basins were measured during two years, and TP loads were measured for two basins. The agronomic P tests showed that 46 to 83% (depending on the test) of the area tested above optimum for crops. Correlations among tests were high for OP, M3P, and FeP (r > 0.96) and lower for BP and WP (r = 0.88–0.93). Moldboard‐ and chisel‐plow tillage predominated (82% of the area). Applied P (mainly fertilizer) averaged 15 kg P ha−1 yr−1, and 40% of the high‐testing area (M3P test) was being fertilized. The mean annual water TP concentration across five basins was 275 to 474 μg L−1 The two‐year mean TP loads for the two gauged basins were 1504 and 1510 g P ha−1 yr−1 Water TP concentration increased linearly with increasing STP. Relationships were stronger for M3P and FeP (R2 = 0.96–0.97 for annual means and 0.77–0.79 for storm‐flow events) than for BP or WP (R2 = 0.88–0.91 and 0.59–0.69, respectively). Improving P and soil conservation practices in high‐testing areas could reduce P loads to the lake.
Simulating Pesticide Leaching and Runoff in Rice Paddies with the RICEWQ–VADOFT Model
Authors: Miao Zewei , Cheplick Mark J. , Williams Martin W. , Trevisan Marco , Padovani Laura , Gennari Mara , Ferrero Aldo , Vidotto Francesco , Capri Ettore 
Published: June 2010

ABSTRACTThere is a current need to simulate leaching and runoff of pesticide from rice (Oryza sativa L.) paddies for assessing environmental impacts on a valuable agricultural system. The objective of this study was to develop a model for determining predicted environmental concentration (PEC) in soil, runoff, and ground water through the linkage of two models, rice water quality model (RICEWQ) and vadose zone transport model (VADOFT), to simulate pesticide fate and transport within a rice paddy and underlying soil profile. Model performance was evaluated with a field data set obtained from a 2‐yr field experiment in 1997 and 1998 in northern Italy. The predictions of amount of pesticide running off from the paddy field and accumulating in the paddy sediment were in agreement with measured values. Leaching into the vadose zone accounted for approximately 19% of the applied dose, but only a small amount of chemical (<0.1%) was predicted to reach ground water at a 5‐m depth due to sorption and transformation in the soil. The permeability of the soil and the water management practices in the paddy field were shown to have a strong influence on pesticide fate. These factors need to be well characterized in the field if model predictions are to be successful. The combined model developed in this work is an effective tool for exposure assessments for soil, surface water, and ground water, in the particular conditions of rice cultivation.
Phenols and Flavonoids in Aleppo Pine Needles as Bioindicators of Air Pollution
Authors: Robles Christine , Greff Stéphane , Pasqualini Vanina , Garzino Suzanne , Bousquet‐Mélou Anne , Fernandez Catherine , Korboulewsky Nathalie , Bonin Gilles 
Published: June 2010

ABSTRACTThe aim of the present study is to assess whether certain ecophysiological responses (contents of total phenols, total proanthocyanidins, and total and simple flavonols), in the needles of Aleppo pines (Pinus halepensis Mill.) may be valid bioindicators for the assessment of the air quality. Samples were taken at five natural sites polluted by various pollutants (NO, NO2, other NOx, SO2, and O3). The results show a decrease in total phenol concentrations with levels of nitrogen oxide pollutions (significant negative correlations between the total phenol concentrations and concentrations of NO, NO2, and other NOx). Total flavonoids (total flavonols and proanthocyanidins) are useful bioindicators for ozone pollution (significant negative correlations between total proanthocyanidins and the concentrations of ozone and significant positive correlations between total flavonols and the ozone pollution). Sulfur dioxide pollution is distinguished by low concentrations in quercetin, isorhamnetin, and kaempferol (significant negative correlations between these simple flavonols and the concentrations of SO2). This work confirms the strong interest of using the phenolic compounds of Pinus halepensis as biological indicators of air quality.