bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphorus Runoff from Two Water Sources on a Calcareous Soil
Authors: Aase J.K. , Bjorneberg D.L. , Westermann D.T. 
Published: June 2010

ABSTRACTPhosphorus (P) in irrigation runoff may enrich offsite water bodies and streams and be influenced by irrigation water quality and antecedent soil surface conditions. Runoff, soil loss, and P fractions in runoff using reverse osmosis (RO) water or mixed RO and well water (RO/Tap) were studied in a laboratory sprinkler study to evaluate water source effects on P transport. A top‐ or subsoil Portneuf silt loam (coarse‐silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid), either amended or not amended with manure and/or with cheese whey, with Olsen P from 20 to 141 mg kg−1and lime from 108 to 243 g kg−1, was placed in 1.5 × 1.2 × 0.2‐m‐deep containers with 2.4% slope and irrigated three times from a 3‐m height for 15 min, applying 20 mm of water. The first irrigation was on a dry loose surface, the second on a wet surface, and the third on a dry crusted surface. Surface (ca. 2 cm) soil samples, prior to the first irrigation, were analyzed for Olsen P, water‐soluble P (Pws), and iron‐oxide impregnated paper–extractable P (FeO‐P) analyses. Following each irrigation we determined runoff, sediment, dissolved reactive phosphorus (DRP) in a 0.45‐μm filtered sample, and FeO‐P and total P in unfiltered samples. Soil surface conditions had no effect on P runoff relationships. Water source had no significant effect on the relationship between DRP or FeO‐P runoff and soil test P, except for DRP in RO runoff versus water‐soluble soil P (r2= 0.90). Total P in RO runoff versus soil P were not related; but weakly correlated for RO/Tap (r2< 0.50). Water source and soil surface conditions had little or no effect on P runoff from this calcareous soil.
Inverse Analyses of Transport of Chlorinated Hydrocarbons Subject to Sequential Transformation Reactions
Authors: Casey Francis X.M. , Šimůnek Jiří 
Published: June 2010

ABSTRACTChemical and biological transformations can significantly affect contaminant transport in the subsurface. To better understand such transformation reactions, an equilibrium–nonequilibrium sorption transport model, HYDRUS‐1D, was modified by including inverse solutions for multiple breakthrough curves resulting from the transport of solutes undergoing sequential transformations. The inverse solutions were applied to miscible‐displacement experiments involving dissolved concentrations of trichloroethylene (TCE) undergoing reduction and/or transformations in the presence of zero‐valent metal porous media (i.e., iron or copper‐coated iron filings) to produce ethylene. The inverse model solutions provided a reasonable description of the transport and transformation processes. Simultaneous fitting of multiple breakthrough curves of TCE and ethylene placed additional constraints on the inverse solution and improved the reliability of parameter estimates. Confidence intervals of optimized parameters were reduced significantly in comparison with those obtained by fitting TCE breakthrough curves independently. Further evidence for accurate parameter estimates was given when the parameter values agreed with previously reported values from independent batch and degradation experiments. Optimized values of the normalized degradation rates for the equilibrium (1.4 × 10−4 to 7.2 × 10−5 L h−1 m−2) and nonequilibrium (1.2 × 10−4 to 5.5 × 10−5 L h−1 m−2) models compared well with values (0.03 to 6.5 × 10−5 L h−1 m−2) obtained from previous studies. The estimated TCE–iron sorption coefficients (0.52 to 2.85 L kg−1) were also consistent with a previously reported value (1.47 L kg−1).
Spatio–Temporal Patterns of Soil Phosphorus Enrichment in Everglades Water Conservation Area 2A
Authors: DeBusk W.F. , Newman S. , Reddy K.R. 
Published: June 2010

ABSTRACTThe Florida Everglades have undergone significant ecological change resulting from anthropogenic manipulation of historical regimes of hydrology, nutrient loading, and fire. Water Conservation Area 2A (WCA‐2A) in the northern Everglades has been a focal point for the study of ecological effects of nutrient loading, especially phosphorus (P), from the nearby Everglades Agricultural Area (EAA). The overall objective of our study was to evaluate recent (1990 to 1998) changes in the spatial extent and patterns of soil P enrichment in Everglades WCA‐2A. Surface soil was sampled to a depth of 10 cm at 62 sites within WCA‐2A during 1998 for analysis of total phosphorus (TP) content. Geostatistical methods were used to create an interpolated grid of soil TP values across WCA‐2A. Comparison of the results of this study with a similar study performed in 1990 showed that the extent of soil P enrichment in surface soil and sediments increased between 1990 and 1998, as evidenced by increased coverage of highly P‐enriched soil near the primary surface inflows and a general increase in the concentration of soil TP in the interior regions of WCA‐2A. Approximately 73% (31777 ha) of the total land area of WCA‐2A was considered P‐enriched (soil total P > 500 mg kg−1) in 1998, compared with 48% of the land area (20829 ha) in 1990, an average increase of 1327 ha yr−1Study results indicate that the soil P enrichment “front” has advanced further into the relatively unimpacted interior of WCA‐2A during the past several years.
A Modified Risk Assessment to Establish Molybdenum Standards for Land Application of Biosolids
Authors: O'Connor George A. , Brobst Robert B. , Chaney Rufus L. , Kincaid Ron L. , McDowell Lee R. , Pierzynski Gary M. , Rubin Alan , Van Riper Gary G. 
Published: June 2010

ABSTRACTThe USEPA standards (40 CFR Part 503) for the use or disposal of sewage sludge (biosolids) derived risk‐based numerical values for Mo for the biosolids → land → plant → animal pathway (Pathway 6). Following legal challenge, most Mo numerical standards were withdrawn, pending additional field‐generated data using modern biosolids (Mo concentrations <75 mg kg−1) and a reassessment of this pathway. This paper presents a reevaluation of biosolids Mo data, refinement of the risk assessment algorithms, and a reassessment of Mo‐induced hypocuprosis from land application of biosolids. Forage Mo uptake coefficients (UC) are derived from field studies, many of which used modern biosolids applied to numerous soil types, with varying soil pH values, and supporting various crops. Typical cattle diet scenarios are used to calculate a diet‐weighted UC value that realistically represents forage Mo exposure to cattle. Recent biosolids use data are employed to estimate the fraction of animal forage (FC) likely to be affected by biosolids applications nationally. Field data are used to estimate long‐term Mo leaching and a leaching correction factor (LC) is used to adjust cumulative biosolids application limits. The modified UC and new FC and LC factors are used in a new algorithm to calculate biosolids Mo Pathway 6 risk. The resulting numerical standards for Mo are cumulative limit (RPc) = 40 kg Mo ha−1, and alternate pollutant limit (APL) = 40 mg Mo kg−1 We regard the modifications to algorithms and parameters and calculations as conservative, and believe that the risk of Mo‐induced hypocuprosis from biosolids Mo is small. Providing adequate Cu mineral supplements, standard procedure in proper herd management, would augment the conservatism of the new risk assessment.
Spatiotemporal Variability of Wet Atmospheric Nitrogen Deposition to the Neuse River Estuary, North Carolina
Authors: Whitall David R. , Paerl Hans W. 
Published: June 2010

ABSTRACTExcessive nitrogen (N) loading to N‐sensitive waters such as the Neuse River estuary (North Carolina) has been shown to promote changes in microbial and algal community composition and function (harmful algal blooms), hypoxia and anoxia, and fish kills. Previous studies have estimated that wet atmospheric deposition of nitrogen (WAD‐N), as deposition of dissolved inorganic nitrogen (DIN: NO−3, NH3/NH+4) and dissolved organic nitrogen, may contribute at least 15% of the total externally supplied or “new” N flux to the coastal waters of North Carolina. In a 3‐yr study from June 1996 to June 1999, we calculated the weekly wet deposition of inorganic and organic N at eleven sites on a northwest–southeast transect in the watershed. The annual mean total (wet DIN + wet organics) WAD‐N flux for the Neuse River watershed was calculated to be 956 mg N/m2/yr (15026 Mg N/yr). Seasonally, the spring (March–May) and summer (June–August) months contain the highest total weekly N deposition; this pattern appears to be driven by N concentration in precipitation. There is also spatial variability in WAD‐N deposition; in general, the upper portion of the watershed receives the lowest annual deposition and the middle portion of the watershed receives the highest deposition. Based on a range of watershed N retention and in‐stream riverine processing values, we estimate that this flux contributes approximately 24% of the total “new” N flux to the estuary.
Movement of Coliform Bacteria and Nutrients in Ground Water Flowing through Basalt and Sand Aquifers
Authors: Entry James A. , Farmer Neal 
Published: June 2010

ABSTRACTLarge‐scale deposition of animal manure can result in contamination of surface and ground water and in potential transfer of disease‐causing enteric bacteria to animals or humans. We measured total coliform bacteria (TC), fecal coliform bacteria (FC), NO3, NH4, total P, and PO4in ground water flowing from basalt and sand aquifers, in wells into basalt and sand aquifers, in irrigation water, and in river water. Samples were collected monthly for 1 yr. Total coliform and FC numbers were always higher in irrigation water than in ground water, indicating that soil and sediment filtered most of these bacteria before they entered the aquifers. Total coliform and FC numbers in ground water were generally higher in the faster flowing basalt aquifer than in the sand aquifer, indicating that the slower flow and finer grain size may filter more TC and FC bacteria from water. At least one coliform bacterium/100 mL of water was found in ground water from both basalt and sand aquifers, indicating that ground water pumped from these aquifers is not necessarily safe for human consumption according to the American Public Health Association and the USEPA. The NO3concentrations were usually higher in water flowing from the sand aquifer than in water flowing from the basalt aquifer or in perched water tables in the basalt aquifer. The PO4concentrations were usually higher in water flowing from the basalt aquifer than in water flowing from the sand aquifer. The main concern is fecal contamination of these aquifers and health consequences that may arise from human consumption.
A Transport Model with Coupled Ternary Exchange and Chemisorption Retention for Hydrazinium Cations
Authors: Mansell R. S. , Bloom S. A. , Downs W. C. 
Published: June 2010

ABSTRACTA numerical model was developed to describe the fate and transport of hydrazinium N2H+5and competing Ca2+and H+cations applied in acidic solutions to columns of Ca2+/H+–saturated sandy soil during steady saturated flow conditions. Instantaneous ternary H+–Ca2+–N2H+5cation exchange using the Gaines–Thomas approach was combined with second‐order, irreversible, kinetic chemisorption of exchange‐phase N2H+5ions as major retention mechanisms for N2H+5Exchange‐mediated chemisorption is assumed to occur as chemical binding of N2H+5ions located on carboxyl‐group exchange sites to nearby carbonyl groups, consequently decreasing the effective soil cation exchange capacity (CEC). Comparison of simulated and observed breakthrough curves (BTCs) for concentrations of N2H+5and Ca2+ions in column effluent was used in model evaluation. The cation transport model with cation exchange coupled with exchange‐mediated chemisorption provided a valid first approximation for N2H+5transport.
A Desorption–Dissolution Model for Metal Release from Polluted Soil under Reductive Conditions
Authors: Davranche Mélanie , Bollinger Jean‐Claude 
Published: June 2010

ABSTRACTVarious natural or provoked situations can cause significant variations in redox conditions that can induce reductive dissolution of soil components. When this happens, heavy metals that may be bound to solid phases are released. A surface desorption–dissolution model, which takes into account the effect of reductive conditions on surface site density, was established. This model is based on conventional reactions of surface hydroxyl groups, surface complexation reactions with cations and double‐layer theory. The solid dissolution rate was taken into account, by following changes in total surface site number (i.e., cation exchange capacity [CEC]) under reductive conditions. This term was introduced in an electrostatic desorption model. Curves obtained by this calculation provided a good fit of experimental data as shown by statistical parameters. Experimental data corresponded to Pb and Cd released from a cultivated soil under reductive conditions induced by sodium ascorbate.
Phosphorus Export from an Agricultural Watershed: Linking Source and Transport Mechanisms
Authors: McDowell Richard , Sharpley Andrew , Folmar Gordon 
Published: June 2010

ABSTRACTMany source and transport factors control P loss from agricultural landscapes; however, little information is available on how these factors are linked at a watershed scale. Thus, we investigated mechanisms controlling P release from soil and stream sediments in relation to storm and baseflow P concentrations at four flumes and in the channel of an agricultural watershed. Baseflow dissolved reactive phosphorus (DRP) concentrations were greater at the watershed outflow (Flume 1; 0.042 mg L−1) than uppermost flume (Flume 4; 0.028 mg L−1). Conversely, DRP concentrations were greater at Flume 4 (0.304 mg L−1) than Flume 1 (0.128 mg L−1) during stormflow. Similar trends in total phosphorus (TP) concentration were also observed. During stormflow, stream P concentrations are controlled by overland flow–generated erosion from areas of the watershed coincident with high soil P. In‐channel decreases in P concentration during stormflow were attributed to sediment deposition, resorption of P, and dilution. The increase in baseflow P concentrations downstream was controlled by channel sediments. Phosphorus sorption maximum of Flume 4 sediment (532 mg kg−1) was greater than at the outlet Flume 1 (227 mg kg−1). Indeed, the decrease in P desorption between Flumes 1 and 4 sediment (0.046 to 0.025 mg L−1) was similar to the difference in baseflow DRP between Flumes 1 and 4 (0.042 to 0.028 mg L−1). This study shows that erosion, soil P concentration, and channel sediment P sorption properties influence streamflow DRP and TP. A better understanding of the spatial and temporal distribution of these processes and their connectivity over the landscape will aid targeting remedial practices.
Prediction of Soil Organic Partition Coefficients by a Soil Leaching Column Chromatographic Method
Authors: Xu Feng , Liang Xinmiao , Lin Bingcheng , Su Fan , Schramm Karl‐Werner , Kettrup Antonius 
Published: June 2010

ABSTRACTThe soil organic partition coefficient (Koc) is one of the most important parameters to depict the transfer and fate of a chemical in the soil–water system. Predicting Koc by using a chromatographic technique has been developing into a convenient and low‐cost method. In this paper, a soil leaching column chromatograpy (SLCC) method employing the soil column packed with reference soil GSE 17201 (obtained from Bayer Landwirtschaftszentrum, Monheim, Germany) and methanol–water eluents was developed to predict the Koc of hydrophobic organic chemicals (HOCs), over a log Koc range of 4.8 orders of magnitude, from their capacity factors. The capacity factor with water as an eluent k′w could be obtained by linearly extrapolating capacity factors in methanol–water eluents (k′) with various volume fractions of methanol (φ). The important effects of solute activity coefficients in water on k′w and Koc were illustrated. Hence, the correlation between log Koc and log k′w (and log k′) exists in the soil. The correlation coefficient (r) of the log Koc vs. log k′w correlation for 58 apolar and polar compounds could reach 0.987, while the correlation coefficients of the log Koc–log k′ correlations were no less than 0.968, with φ ranging from 0 to 0.50. The smaller the φ, the higher the r Therefore, it is recommended that the eluent of smaller φ, such as water, be used for accurately estimating Koc Correspondingly, the r value of the log Koc–log k′w correlation on a reversed‐phase Hypersil ODS (Thermo Hypersil, Kleinostheim, Germany) column was less than 0.940 for the same solutes. The SLCC method could provide a more reliable route to predict Koc indirectly from a correlation with k′w than the reversed‐phase liquid chromatographic (RPLC) one.
Toxicity of Ozonated Animal Manure to the House Fly, Musca domestica
Authors: Masten Susan J. , Kim‐Yang Hyesoon , Walker Edward D. , Roman Hugo , Yokoyama Melvin T. 
Published: June 2010

ABSTRACTSwine manure slurries were ozonated at a dosage of 1 g/L and tested for their toxicity to the house fly (Musca domestica). The observed toxicity of ozonated swine manure was consistent and independent of origin of the swine manure. A dose (dilution) response curve was performed. A 50% dilution in the ozonated swine manure slurry resulted in 90% reduction in toxicity. Neither the synthetic nor ozonated synthetic swine manure, both of which contained higher concentrations of formaldehyde and three other unidentified carbonyl compounds than the ozonated swine manure, were toxic to the flies. Ozonated swine manure slurry was centrifuged and passed through a 0.45‐μm filter. The liquid phase was as toxic as the unfiltered slurry; as such, the toxicant appears to be present in liquid phase. Neither ammonia, hydrogen sulfide, formaldehyde, nor other simple aldehydes appeared to be the toxic agent. The toxic agent appears to be a polar chemical compound and is concentrated in the urine. Several possible compounds have been identified. The toxicity of untreated and ozonated manure slurries from different livestock was compared. Six animal manure slurries (beef and dairy cattle, horse, poultry, sheep, and swine) were ozonated (dosage of 1 g/L) and tested for toxicity to the house fly. Ozonated dairy cattle manure slurry showed 78% mortality after 72 h, whereas ozonated swine manure slurry achieved a 100% mortality rate in 48 h. Neither the unozonated dairy nor swine manure slurries, nor any of the other raw or ozonated manure slurries, were toxic to the flies.
Oxidation of Phenolic Acid Derivatives by Soil and Its Relevance to Allelopathic Activity
Authors: Ohno Tsutomu 
Published: June 2010

ABSTRACTPrevious studies have suggested that phenolic acids from legume green manures may contribute to weed control through allelopathy. The objectives of this study were to investigate the oxidation reactions of phenolic acids in soil and to determine the subsequent effects of oxidation upon phytotoxicity. Soils were reacted for 18 h with 0.25 mmol L−1 benzoic and cinnamic acid derivative solutions and Mn release from the suspension was used as a marker for phenolic acid oxidation. The extent of oxidation in soil suspensions was in the order of 3,4‐dihydroxy‐ > 4‐hydroxy‐3‐methoxy‐ > 4‐hydroxy‐ ≅ 2‐hydroxy–substituted benzoic and cinnamic acids. The same ranking was observed for cyclic voltammetry peak currents of the cinnamic acid derivatives. This suggests that the oxidation of phenolic acids is controlled by the electron transfer step from the sorbed phenolic acid to the metal oxide. A bioassay experiment showed that the 4‐hydroxy‐, 4‐hydroxy‐3‐methoxy‐, and 3,4‐dihydroxy–substituted cinnamic acids were bioactive at 0.25 mmol L−1 concentration. Reaction with soil for 18 h resulted in the elimination of bioactivity of these three cinnamic acids at the 5% significance level. The oxidative reactivity of phenolic acids may limit the potential of allelopathy as a component of an integrated weed management system. However, the initial phytotoxicity after soil incorporation may coincide with the early, critical stage of weed emergence and establishment, so that allelopathic phenolic acids may still play a role in weed management despite their reactivity in soil systems.
Field‐Scale Remediation of a Metolachlor‐Contaminated Spill Site Using Zerovalent Iron
Authors: Comfort S. D. , Shea P. J. , Machacek T. A. , Gaber H. , Oh B.‐T. 
Published: June 2010

ABSTRACTPesticide spills are common occurrences at agricultural cooperatives and farmsteads. When inadvertent spills occur, chemicals normally beneficial can become point sources of ground and surface water contamination. We report results from a field trial where approximately 765 m3 of soil from a metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] spill site was treated with zerovalent iron (Fe0). Preliminary laboratory experiments confirmed metolachlor dechlorination by Fe0 in aqueous solution and that this process could be accelerated by adding appropriate proportions of Al2(SO4)3 or acetic acid (CH3COOH). The field project was initiated by moving the stockpiled, contaminated soil into windrows using common earth‐moving equipment. The soil was then mixed with water (0.35–0.40 kg H2O kg−1) and various combinations of 5% Fe0 (w/w), 2% Al2(SO4)3 (w/w), and 0.5% acetic acid (v/w). Windrows were covered with clear plastic and incubated without additional mixing for 90 d. Approximately every 14 d, the plastic sheeting was removed for soil sampling and the surface of the windrows rewetted. Metolachlor concentrations were significantly reduced and varied among treatments. The addition of Fe0 alone decreased metolachlor concentration from 1789 to 504 mg kg−1 within 90 d, whereas adding Fe0 with Al2(SO4)3 and CH3COOH decreased the concentration from 1402 to 13 mg kg−1 These results provide evidence that zerovalent iron can be used for on‐site, field‐scale treatment of pesticide‐contaminated soil.
Runoff Loss of Pesticides and Soil: A Comparison between Vegetative Mulch and Plastic Mulch in Vegetable Production Systems
Authors: Rice Pamela J. , McConnell Laura L. , Heighton Lynne P. , Sadeghi Ali M. , Isensee Allan R. , Teasdale John R. , Abdul‐Baki Aref A. , Harman‐Fetcho Jennifer A. , Hapeman Cathleen J. 
Published: June 2010

ABSTRACTCurrent vegetable production systems use polyethylene (plastic) mulch and require multiple applications of agrochemicals. During rain events, runoff from vegetable production is enhanced because 50 to 75% of the field is covered with an impervious surface. This study was conducted to quantify off‐site movement of soil and pesticides with runoff from tomato (Lycopersicon esculentum Mill.) plots containing polyethylene mulch and a vegetative mulch, hairy vetch (Vicia villosa Roth). Side‐by‐side field plots were instrumented with automated flow meters and samplers to measure and collect runoff, which was filtered, extracted, and analyzed to determine soil and pesticide loss. Seasonal losses of two to four times more water and at least three times as much sediment were observed from plots with polyethylene mulch (55.4 to 146 L m−2 and 247 to 535 g m−2, respectively) versus plots with hairy vetch residue (13.7 to 75.7 L m−2 and 32.8 to 118 g m−2, respectively). Geometric means (±standard deviation) of total pesticide loads for chlorothalonil (tetrachloroisophthalonitrile) and α‐ and β‐endosulfan (6,7,8,9,10,10‐hexachloro‐1,5,5a,6,9,9a‐hexahydro‐6,9‐methano‐2,4,3‐benzodioxathiepin 3‐oxide) for a runoff event were 19, 6, and 9 times greater from polyethylene (800 ± 4.6, 17.6 ± 3.9, and 39.1 ± 4.9 μg m−2, respectively) than from hairy vetch mulch plots (42 ± 6.0, 2.8 ± 5.0, and 4.3 ± 4.6 μg m−2, respectively) due to greater concentrations and larger runoff volumes. The increased runoff volume, soil loss, and off‐site loading of pesticides measured in runoff from the polyethylene mulch suggests that this management practice is less sustainable and may have a harmful effect on the environment.