bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Wind Tunnel for Measuring Selenium Volatilization under Field‐Like Conditions
Authors: Dungan R. S. , Stork A. , Frankenberger W. T. 
Published: July 2010

AbstractA wind tunnel was developed to measure the loss of volatile selenium (Se) from soil under field‐like conditions. The wind tunnel consisted of a volatilization chamber made of Plexiglas (2.4 m long × 0.8 m wide × 1.2 m high), which was set above a stainless steel lysimeter (0.5 m2 surface area × 0.8 m deep). High air exchange rates (avg. 700 air changes h−1) were used to simulate field‐like environmental conditions inside the wind tunnel. To monitor the fate and transport of the Se, radiolabeled 75Se as sodium selenite (Na275SeO3) was incorporated into the top 5 cm of soil. Volatile Sc was trapped on activated carbon filters and measured directly using gamma counting. A 135‐d bare‐soil experiment was carried out, during which 2.7% of the Se was released through volatilization without added C. The average flux rate of gaseous Se was 17 mg m−2 h−1, with a high of 72 mg m−2 h−1 occurring on Day 6. After 135 d, 59 and 34% of the 75Se was located in the 0 to 5 and 5 to 10 cm soil layers, respectively. A total of 84.5% of all applied 75Se was recovered. The purpose of this study was to improve estimates on Se volatilization from seleniferous soils and help close the gap between previous laboratory and field experiments.
Anthropogenic Inputs of Nitrogen and Phosphorus and Riverine Export for Illinois, USA
Authors: David Mark B. , Gentry Lowell E. 
Published: July 2010

AbstractAgricultural nonpoint sources are important contributors of N and P to surface waters. We determined N and P net anthropogenic inputs for Illinois, examining changes during the last 50 yr and linkages to surface water export of N and P. Inputs (fertilizer, atmospheric deposition, and N2 fixation) were compared to exports (grain export, after accounting for animal and human consumption, plus animal product export) from 1945 through 1998 using state‐reported data on fertilizer sales, crop production, and human and animal populations. Large inputs of N were found beginning about 1965, coinciding with increased N fertilizer applications (about 800 000 Mg N yr−1). The N input (about 400 000 Mg N yr−1) was 8.6 million Mg N for the 1979 to 1996 crop years, with a corresponding riverine flux of 4.4 million Mg N (51% of net anthropogenic inputs discharged by rivers). Using literature estimates of field and in‐stream denitrification, we could account for nearly all of the missing N in a mass balance. For P, a different paflern was found for state net anthropogenic inputs with a large input from 1965 to 1990, and on average no net inputs since 1990. For rivers, we estimated that 16% of the total N load and 47% of the total P load was from sewage effluent. We estimate that Illinois contributed 15 and 10% of the annual total N and P loads of the Mississippi River, respectively, and that any reduction strategy in Illinois must address agricultural sources.
Effect of Mineral Colloids on Virus Transport through Saturated Sand Columns
Authors: Jin Yan , Pratt Ellen , Yates Marylynn V. 
Published: July 2010

AbstractStudies have indicated that colloids are capable of adsorbing and enhancing the transport of a variety of contaminants in soil, fractured rocks, and ground water. The purpose of this study was to determine the role of mineral colloids on the fate and transport of viruses through porous media. Experiments were conducted to examine the influence of several mineral colloids [kaolinite, Ca‐montmorillonite (Ca‐M), and Na‐montmorillonite (Na‐M)] on the movement of a bacteriophage (MS2) through sand columns under saturated flow conditions. Input solution containing MS2 and Br− tracer was applied to the column as a pulse function while colloids were introduced as a step function. Effluent samples were collected in a fraction collector and analyzed for Br−, virus, and colloids. The convection‐dispersion equation (CDE), partially calibrated with the transport parameters measured from the Br− signal, was used to evaluate the transport characteristics of both the virus and colloids. Transport of both the colloids and MS2 through sand columns was described well by the CDE when a first‐order kinetic removal process was assumed. The bacteriophage MS2 was adsorbed by colloids to various degrees and in the order of fine Na‐M > coarse Na‐M > Ca‐M ∼ kaolinite. The amount of colloids transported through the columns followed the same order. The Na‐M greatly enhanced MS2 transport through the sand columns and the effect was more significant when the clay particles were ground into smaller sizes. The extent of colloid‐facilitated MS2 transport was clearly correlated with the extent of colloid transport and the number of viruses adsorbed to colloidal particles. To our knowledge, this study demonstrates for the first time the possible effect of colloids in facilitating virus transport through porous media.
A Multiplexed Fiber Optic Miniprobe System for Measuring Solute Transport in Soil
Authors: Ghodrati Masoud , Garrido Fernando , Campbell Chris G. , Chendorain Michael 
Published: July 2010

AbstractA fiber optic miniprobe (FOMP) system has been recently developed, capable of measuring solute breakthrough curves (BTCs) in situ and in real time at a single point within the soil matrix. We have multiplexed this system to allow continuous operation of up to 20 of these FOMPs simultaneously. The system was used to measure replicated multipoint BTCs of a fluorescent tracer in a large silica sand column, and allowed verification of the multiplexed FOMP system's ability to measure transport at a point scale. We performed seven miscible displacement studies (runs) generating 140 BTCs to examine system performance, transport variability measured at a small scale, and the sensitivity of that variability to changes in initial pulse concentration (Co). The convective‐dispersive equation (CDE) was adequate to describe transport in the silica sand (r2 > 0.96). However, tails observed in all the BTCs were attributed to an immobile phase by fitting several BTCs to a resident concentration form of the mobile‐immobile model (MIM). The mass recovery of the tracer ranged from 73 to 127% with an average of 98%. Changes in column averaged transport parameters for the seven miscible displacement studies were minimal; however, there appears to be no consistency in transport at the measurement scale of the probes. Small changes in Co were not found to significantly alter or change the variability in transport parameters. The multiplexed fiber optic system was found to be an accurate tool for small‐scale characterization of solute transport in soil.
Biodegradation of Fuel Oil Hydrocarbons in the Rhizosphere of Maize
Authors: Chaîneau C. H. , Morel J. L. , Oudot J. 
Published: July 2010

AbstractPlant roots provide suitable habitats for the growth of microorganisms. Particularly, the release of exudates by living roots enhances the microbial activity in the rhizosphereo This work was undertaken in the laboratory to study the biodegradation of fuel oil hydrocarbons (HC) in the presence of growing plants and to assess the effects of root exudates on biodegradation. Maize (Zea mays L.) plants were grown in soil microcosms for 120 d and in liquid (hydroponic) cultures for 40 d in presence and in absence of fuel oil added at slightly phytotoxic concentrations (soil: 3300 mg kg−1; hydroponic cultures: 850 mg L−1). Controls without plants permitted the quantification of the rhizosphere effects on HC removal. Concentration and chemical composition of residual HC were periodically determined. Higher degradation rates of saturated and aromatic HC were observed in soil in the presence of plants in the early stages of biodegradation when maize growth was exponential. No significant change was observed in the polar fraction. After 120 d, the biodegradation rates were identical in the presence or absence of plants. In hydroponic conditions, a stimulation in the degradation of saturates was observed until Day 40. No significant difference was detected in the aromatic fraction. The faster biodegradation of HC in the presence of plants was attributed to the changes in environmental conditions in the rhizosphere; e.g., increase of HC bioavailability, stimulation of bacterial populations due to plant exudation and effects on physical properties of soil. Competition for mineral nutrients between plants and microorganisms was shown.
Nitrogen Retention and Release in Atlantic White Cedar Wetlands
Authors: Zhu Wei‐Xing , Ehrenfeld Joan G. 
Published: July 2010

AbstractThe fate of N inputs to freshwater wetlands from enriched runoff, ground water, or atmospheric deposition reflects a variety of processes that determine the net retention of N or its release to downstream ecosystems. The history of N enrichment may affect the relative importance of different pathways. We compared the ability of sediments from Atlantic cedar wetlands in suburban and undisturbed watersheds to remove added inorganic N in laboratory incubations. Three pulses of NH4NO3, at 50 mg N L−1 concentration, were added at consecutive 2‐wk intervals as an analog of pulsed stormwater inputs. After each incubation, soils were leached with CaCl2 and inorganic N concentrations in the leachate were analyzed. The peats retained added N during the first incubation, but after the second and third, all soils released more N than had been added. Nitrate concentrations were always lower than ammonium concentrations. Soils from hollows and most hummocks retained added nitrate throughout the study, but all soils released ammonium. Soil extractable ammonium increased four to 10 times after the 6‐wk incubation, while extractable dissolved organic N (DON) decreased. There also was a net decrease of soil total Kjeldahl N (TKN). The patterns of retention and release of nitrate and ammonium were correlated positively with the N mineralization and nitrification rates of the soils. Our results suggest that wetland peats in suburban drainages may have limited ability to retain frequent, pulsed N inputs from runoff and high intrinsic N mineralization in N‐saturated sediments can become a cause of water quality degradation.
Nitrous and Nitrogen Oxide Emissions from Turfgrass Receiving Different Forms of Nitrogen Fertilizer
Authors: Maggiotto S. R. , Webb J. A. , Wagner‐Riddle C. , Thurtell G. W. 
Published: July 2010

AbstractThe use of N fertilizer in agriculture is considered an important source of atmospheric N2O and NOx. Choice of fertilizer type and management has been considered a method for mitigating these emissions. Micrometeorological methods were used to study the effect of inorganic N fertilizers urea (U), slow‐release urea (SRU), and ammonium nitrate (AN) on fluxes of N2O, NO, and NO2 from turfgrass field plots during three seasons, from 1995 to 1997 (total of 353 d of measurement). Daily average fluxes after fertilizations reached a maximum of 2091 ng N2O‐N m−2 s−1 after the first fertilization with AN in 1996. The fertilized plots had significantly higher emissions (P < 0.05) than the control plot, and the highest N2O emissions were from AN in 1995 and 1996, and from SRU in 1997. Daily fluxes of up to 186 ng NO‐N m−2 s−1 were measured within 1 wk following fertilization in 1997. The U plot had significantly higher NO emissions during all seasons compared with other fertilized plots. Fluxes of NOx during 1996 and 1997 were consistently downward, indicating that turfgrass was acting as a sink for NOx. NO2 uptake seemed to be directly related to NO emissions, and the U plot presented the highest NO2 uptake. Urea‐based fertilizers seem to minimize N2O emissions, although long‐term effects of SRU still need to be studied. The higher NO emissions from U‐based fertilized plots do not seem to be a problem, since NOx uptake occurred at higher rates than NO emission.
Two‐Dimensional Model Simulation of 1,3‐Dichloropropene Volatilization and Transport in a Field Soil
Authors: Wang D. , Knuteson J. A. , Yates S. R. 
Published: July 2010

AbstractA modeling study was conducted to simulate 1,3‐dichloropropene (1,3‐D) emission and concentration distribution in soil profiles when the chemical was applied with subsurface drip irrigation with reduced rate. The purpose was to evaluate the effect on emission reduction as compared with conventional shank injection application. To compare with field measurements, simulated scenarios included a shallow drip application at 2.5 cm, covered with a polyethylene film; a deep drip application at 20.3 em with bare soil surface; and a conventional shank injection at 30.5 cm with a regular application rate. A convective and diffusive two‐dimensional model was used to simulate the simultaneous transport of 1,3‐D in both liquid and gaseous phases. Diurnal variations of soil temperature were predicted to calculate 1,3‐D diffusion coefficient and the Henry's constant. Predicted 1,3‐D emissions compared well with field measurements for the shallow and deep drip irrigation treatments. The model simulation underpredicted 1,3‐D emission in the shank injection plot, where other transport mechanisms such as gas phase convection likely occurred during and immediately after application. Results from the modeling study indicate that computer simulation can be used effectively to study the environmental fate and transport of 1,3‐D under conditions where vapor phase diffusion and liquid phase convection are the dominant transport mechanisms. Applying 1,3‐D with subsurface drip irrigation appeared to be useful for emission reduction.
Column System for Concurrent Assessment of Emission Potential and Pest Control of Soil Fumigants
Authors: Gan J. , Hutchinson C. , Ernst F. F. , Becker J. O. , Yates S. R. 
Published: July 2010

AbstractFumigation for soilborne pest and pathogen control is under close scrutiny because of its potential hazardous effects on the environment and on human health. Therefore, reduced‐risk yet effective fumigation practices are imperatively needed. We have developed a column system that allows an integrated evaluation of emission potential and efficacy of fumigants. The system consists of a large, packed soil column and a sampling chamber for measuring fumigant emissions at the soil surface. Nematodes (or other pests) can be inoculated into the column and their survival may be assayed after the treatment. This approach was used to evaluate the emission of 1,3‐dichloropropene (1,3‐D) and its efficacy against the citrus nematode Tylenchulus semipenetrans when ammonium thiosulfate, a 1,3‐D degrading fertilizer, was applied at the soil surface. Results closely comparable to field observations were obtained. Compared with field studies, the proposed method is rapid and inexpensive, and thus may be used for screening fumigation practices that have improved environmental safety and pest control performance.
Phenoloxidase‐Mediated Interactions of Phenols and Anilines with Humic Materials
Authors: Dec Jerzy , Bollag Jean‐Marc 
Published: July 2010

AbstractPhenoloxidases present in terrestrial systems may contribute to the formation of humus through random coupling of a variety of aromatic compounds, including xenobiotic chemicals. Because of their structural similarity to natural substrates originating mainly from ligdin decomposition, xenobiotic phenols and anilines can be readily incorporated into the soil organic matter, a phenomenon referred to as binding. The underlying mechanism of binding involves oxidation of the xenobiotic substrates to free radicals or quinone products that subsequently couple directly to humus or to naturally occurring phenols that also are subject to oxidation. The oxidation can be mediated by soil phenoloxidases as well as by abiotic catalysts. The ability of the enzymes to mediate the oxidation was demonstrated in a number of model studies, in which selected pollutants were incubated with humic monomers or natural humic acids in the presence of different phenoloxidases (laccase, peroxidase, tyrosinase). Analysis of the formed complexes by mass spectrometry and 13C nuclear magnetic resonance (NMR) spectroscopy left no doubt about the formation of covalent bonds between the pollutants and humic materials. Some bonds were formed at the chlorinated sites, leading to partial dehalogenation of the aromatic contaminants. Experimental data indicated that bound phenols and anilines were unlikely to adversely affect the environment; their release from humic complexes by soil microorganisms was very limited and once released, they were subjected to mineralization. For those reasons, phenoloxidases, which proved capable of mediating the underlying reaction, are currently considered as a tool for enhancing immobilization phenomena in soil.
Enzyme‐Clay Interactions and Their Impact on Transformations of Natural and Anthropogenic Organic Compounds in Soil
Authors: Naidja A. , Huang P. M. , Bollag J.‐M. 
Published: July 2010

AbstractSoil is a living system in which enzymes are present either free in solution or bound to clay and clay‐humus complexes. Enzyme‐clay interactions play a key role in transforming organic compounds in soil environments where the decomposition and synthetic processes are largely catalyzed by enzymes. Scientific evidence indicates that mineral colloids take part in the catalysis of degradative and synthetic reactions of organic compounds. Such information is essential to understanding the role of mineral colloids, the hidden half of the enzyme‐mineral colloid complexes, in catalytic reactions. Despite the abundant literature on the enzyme interactions with pure crystalline aluminosilicates, the nature of enzyme association with soil constituents, including both clean and coated clay minerals and other mineral colloids, and the effect on soil processes still remain unclear. This study integrates the existing information, including recent findings on enzyme‐mineral colloid interactions and their effect on natural and anthropogenic organic compound transformation in soil. Further, the study focuses on the catalytic role of enzyme‐clay complex surfaces in toxic industrial and agricultural compound bioremediation in soil and water environments.
Transformation of Chlorinated Hydrocarbons Using Aquocobalamin or Coenzyme F430 in Combination with Zero‐Valent Iron
Authors: Morra Matthew J. , Borek Vladimir , Koolpe Jonathan 
Published: July 2010

AbstractMore effective methods are necessary for the remediation of soils, sediments, and ground waters contaminated with halogenated organic compounds. Our objective was to determine the feasibility and utility of using a tetrapyrrole‐Fe(0) mixture for reductive dehalogenation of synthetic organic contaminants. Aquocobaiamin or coenzyme F430 was combined with Fe(0) in aqueous systems containing either a single chlorinated compound or mixtures of chlorinated compounds, and substrate disappearance was monitored using gas chromatography‐mass spectrometry (GC‐MS). Zero‐valent iron effectively dehalogenated CCl4 at low to neutral pH values, while increases in CCl4 dehalogenation resulting from inclusion of tetrapyrrole catalysts along with Fe(0) occurred only at basic pH values. Rates of CCl4 disappearance increased with additional aquocobalamin, but reached a maximum and decreased at higher aquocobalamin concentrations. Overall dehalogenation rates may thus be a function of Fe(0)'s limited reactive surface area. There was a trend for both tetrapyrrole catalysts to promote the disappearance of halogenated compounds in a mixed substrate containing 20 compounds. Studies with five individual substrates likewise showed trends for increased substrate removal with F430 beyond that for Fe(0) alone. This increase is most important for compounds such as 1,2‐dichloroethane and 1,4‐dichlorobenzene that are not readily dehalogenated by Fe(0). Chloride concentrations in the reaction mixtures indicated that reductive dehalogenation was the dominant process responsible for substrate disappearance. Use of a combination of aquocobalamin or coenzyme F430 and Fe(0) may effectively promote dehalogenation, thus producing fewer products and more complete dehalogenation of the target substrates than can be achieved using only one of the abiotic reductants alone.
Management and Crop Residue Influence Soil Aggregate Stability
Authors: Martens Dean A. 
Published: July 2010

AbstractSoil management is one of the most important factors influencing the structure of soils. The interaction of management (including tillage and crop rotation history) with soil biochemistry, soil aggregation, and soil humus composition was determined in a native prairie and a producer field situation in 1997. A comparison of a native prairie and an adjacent conventional corn (Zea mays L.)‐soybean [Glycine max (L.) Merr.] rotation on the same soil type found that the Webster soil (fine‐loamy, mixed, superactive, mesic Typic Endoaquoll) after soybean (C3 plant) was lower in monosaccharide content and protein content as determined by ion chromatography, and lower in phenolic acid content than the Webster soil after corn (C4 plant) or in native prairie as determined by gas chromatography. A wet, nested sieve aggregate stability measurement determined that the prairie soil had a higher mean aggregate size (1.85 mm) when compared with the soil in the presence of decomposing corn (1.0 mm) or soybean (0.34 mm) residues. Mean aggregate size was found to be correlated with soil monosaccharide content (r = 0.75), total soil protein content (r = 0.995***), total soil phenolic acid content (r = 0.997***), and alkaline extractable humic substance content (r = 0.98**). Alkaline extractable humic substances were correlated with the phenolic acid content of the humic substances (r = 0.996***). The results suggest that the decrease in soil stability after soybean growth was due to a decrease in the content of soil humic substances caused by the substantially lower phenolic acids content (humic acid precursors) in the soybean residue.
Ammonia Emission from a Large Mechanically‐Ventilated Swine Building during Warm Weather
Authors: Ni Ji‐Qin , Heber Albert J. , Lim Teng T. , Diehl Claude A. , Duggirala Ravi K. , Haymore Barry L. , Sutton Alan L. 
Published: July 2010

AbstractAmmonia (NH3) emission from a grow‐finish swine (Sus scrofa) building with an underfloor manure storage pit was evaluated during warm weather from 26 June to 25 September. Average daily mean (ADM, covering all measurement days) outdoor temperature was 21.8°C. Ammonia concentrations, ventilation rates, and temperatures were continuously measured or recorded and 88 d of reliable data were obtained. Air samples were taken at wall and pit exhaust fans and in the pit headspace. The NH3 concentrations were monitored on‐site with a chemiluminescence NH3 analyzer. Ventilation rates were calculated based on operation of five wall fans, four pit fans, and the fan static pressure. The NH3 emission rates were calculated by multiplying simultaneously measured NH3 concentrations and ventilation rates of wall and pit exhaust fans. The ADM of building NH3 concentration (mean concentration of all sampling locations) was 3.9 mg m−1. The ADM building NH, emission (sum of the emissions from all ventilation fans) was 11.2 kg d−1, equivalent to 145 g d−1 per AU (animal unit = 500 kg animal weight). The ADM emission per AU was higher than other reported values, probably due to warmer temperatures and higher ventilation rates. The building NH3 concentrations were inversely proportional to the indoor temperatures (r = −0.66) and ventilation rates (r = −0.59) and correlated well to total pig weight (r = 0.49). The building NH3 emission rates were correlated to total pig weights (r = 0.52) and ventilation rates (r = 0.41) and were not well correlated to indoor temperatures (r = 0.12).