bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant and Soil Relationships of Uranium and Thorium Decay Series Radionuclides—A Review
Authors: Mortvedt J. J. 
Published: July 2010

AbstractThe behavior of radionuclides of the uranium (U) and thorium (Th) decay series in terrestrial systems is of interest because of environmental effects of mining and disposal activities related to nuclear power plant fuels. The soft‐plant relationships of U, Th, and polonium (Po), and some other daughter radionuclides, notably radium (226Ra), are not well understood. Most studies have been concerned with relative uptake of these radionuclides by various plant species. Plant concentrations have been related to total contents of these radionuclides in the soil as a plant/soil concentration ratio (CR), even though the fraction of these radionuclides, which may be available to plants, is not well known. These CR values have been used to predict transport of radionuclides and other elements of interest through the food chain as well as for other purposes, including biogeochemical exploration for U. Little information is available on uptake and transport mechanisms of radionuclides in plants. However, the mechanisms relating to Ca uptake and translocation in plants may be similar to those of some radionuclides, especially 226Ra. Soil chemical reactions of these radionuclides also have not been studied as well as those of plant nutrients, although knowledge of the effects of soil pH, soil texture, and organic matter content on uptake, as well as mobility in soil of these radionuclides, has been gained in recent years.
Microbial Effects on Nickel and Cadmium Sorption and Transport in Volcanic Tuff
Authors: Brown Robin L. , Bowman Robert S. , Kieft Thomas L. 
Published: July 2010

AbstractWe performed sorption and transport experiments to determine how vadose‐zone microbes affect sorption of Ni2+ and Cd2+ on crushed volcanic tuff and transport of Ni2+ in the same medium. Sorption of Ni2+ and Cd2+ to the tuff was less in samples inoculated with microbes than in sterile samples. Since Ni2+ sorption was the same both in the presence and absence of microbes when a buffer was used, microbes appear to decrease sorption by decreasing solution pH. Samples with Bacillus megaterium decreased Ni2+ sorption the most of the 14 subsurface microbial strains tested. Nickel isotherms were linear up to initial concentrations of 10 mg L−1 with an average distribution coefficient (kd) of 7.4 L kg−1 for samples with freeze‐dried B. megaterium and 50 L kg−1 for sterile samples containing 1 g L−1 NaN3. Sterile samples without NaN3 had a higher kd (84–265 L kg−1). We therefore predicted that the retardation of Ni2+ in inoculated columns would be lower than in sterile columns. A transport experiment with both inoculated (inoculum consisted of freeze‐dried B. megaterium) and sterile (solutions contained NaN3) columns indicated that retardation (R) of Ni2+ was less for columns with microbes (R = 205) than for sterile columns (R = 307), but retardation was higher than predicted by batch sorption experiments in both groups of columns. Dispersion was lower in inoculated columns, possibly due to microbial clogging of secondary pores. The results indicate that microbes can increase the mobility of cationic metals in subsurface environments.
Groundwater Nitrate Levels under Fertilized Grass and Grass‐Legume Pastures
Authors: Owens L. B. , Edwards W. M. , Van Keuren R. W. 
Published: July 2010

AbstractHigh levels of N fertilizer applied to pastures can result in NO3‐N concentrations in groundwater exceeding the USEPA potable water standard of 10 mg N/L. This study was conducted to determine groundwater NO3‐N levels following a change in N source from fertilizer to a legume in a grass‐pasture grazed by beef cattle. For 5 yr, 224 kg N/ha was applied annually to small watersheds with orchardgrass (Dactylis glomerata L.) pastures used for summer‐grazing and tall fescue (Festuca arundinacea Schreb.) areas used for winter‐grazing‐feeding. At the beginning of the sixth year, alfalfa (Medicago sativa L.) was interseeded into the grass pastures and N fertilizer was no longer applied. Groundwater sampies from developed springs and surface runoff samples were collected and analyzed for NH4‐N, NO3‐N, and total N for the 5‐yr fertilization period and for the following 10‐yr period without applied N fertilizer. Nitrogen in groundwater was present mainly in the NO3 form, and concentrations increased throughout the 5‐yr period of fertilizer application and reached levels that were usually in excess of 10 mg N/L. With the change from N fertilizer to legume N, the NO3‐N concentrations in groundwater dropped rapidly during a 2‐yr period. In a tall fescue‐alfalfa area, NO3‐N levels decreased from 17.7 to 9.3 mg N/L. In two orchard‐grass‐alfalfa areas, NO3‐N levels decreased from 11.2 to 2.7 and from 8.3 to 3.6 mg N/L. During the remainder of the 10‐yr period, NO3‐N concentrations declined to levels similar to those before N fertilization. Although the amount of N lost via subsurface flow decreased with decreasing concentrations, subsurface flow remained the main pathway for N loss compared with surface runoff or sediment‐attached N.
Volatile Organic Vapor Diffusion and Adsorption in Soils
Authors: Petersen L. W. , Rolston D. E. , Moldrup P. , Yamaguchi T. 
Published: July 2010

AbstractKnowledge of the relationship between DP/D0 (diffusion coefficient in soil divided by diffusion coefficient in free air) and the volumetric soil‐air content, ɛ, is important when modeling gaseous movement of volatile organic compounds (VOCs) in soils. The effective diffusion (i.e., diffusion and retardation) of trichloroethylene (TCE), toluene and freon in Yolo silt loam (fine‐silty, mixed, nonacid, thermic Typic Xerorthent) were measured in a two‐chamber diffusion apparatus. The experiments were conducted on packed soil cores over a range of water contents. Vapor retardation factors were calculated from soil parameters and equilibrium partition coefficients. Partition coefficients were measured in batch experiments. It was found that for water contents higher than four molecular layers of water surface coverage, solid/vapor partition coefficients, KD′, were consistent with values predicted by Henry's Law constants (KH), and aqueous/solid partition coefficients, KD. For less than four molecular layers of water, sorption increased by orders of magnitude. The vapor retardation factors, along with the measured effective diffusion, allowed a calculation of diffusion coefficients (DP) for the investigated species by using the analytical solution to diffusion in a two‐chamber apparatus. Values of the ratio DP/D0 were generally higher than the values predicted by the Millington‐Quirk equation, and lower than the values predicted by the Penman equation. Compared with the nonreactive tracer freon, DP/D0 values for TCE and toluene agreed very well for higher water contents. Values obtained for air‐dry soil, however, were under‐predicted. The experimental work for determination of the effective diffusion of reactive tracers can, therefore, for sufficiently high water contents be limited to the determination of Dp/D0‐ɛ relations for a nonreactive tracer and measurement of KD, KD′, and KH values for the reactive tracers.
Oxygen Respirometry to Assess Stability and Maturity of Composted Municipal Solid Waste
Authors: Iannotti D. A. , Grebus M. E. , Toth B. L. , Madden L. V. , Hoitink H. A. J. 
Published: July 2010

AbstractThe stability and maturity of compost prepared from municipal solid waste (MSW) at a full‐scale composting plant was assessed through chemical, physical, and biological assays. Respiration bioassays used to determine stability (O2 and CO2 respirometry) were sensitive to process control problems at the composting plant and indicated increasing stability with time. Radish (Raphanus sativus L.) and ryegrass (Lolium perenne L.) growth bioassays revealed that immature compost samples inhibited growth. Growth of ryegrass in poring mix prepared with cured compost not amended with fertilizer was enhanced as compared to a peat control. Garden cress (Lepidium sativum L.) seed germination, used as an indicator of phytotoxicity, revealed inhibition of germination at all compost maturity levels. The phytotoxicity was thought to be salt‐related. Spearman rank‐order correlations demonstrated that 02 respirometry, water‐soluble organic C, and the water extract organic C to organic N ratio, significantly correlated with compost age and best indicated an acceptable level of stability. Oxygen respirometry also best predicted the potential for ryegrass growth, and an acceptable level of compost maturity.
Sulfate Sorption in Soils under Acid Deposition: Modeling Field Data from Forest Liming
Authors: Prenzel Jürgen , Meiwes Karl‐Josef 
Published: July 2010

AbstractSulfate sorption can modify the reaction of a soil to acid depositions. Different models of this process exist. In a preceeding paper the adsorption isotherm and the solubility product modeling approach have been compared and a solubility product model has been introduced. The latter model is tested using a forest liming experiment. Concentration data from canopy drip and seepage covering a 20‐yr observation period are used as 3‐yr moving averages. The model assumes a steady seepage flow and uses only one 1‐m compartment. The model considers joint chemical equilibria for gibbsite, jurbanite, cation exchange, and complexation. The seepage pH and concentrations of Al and sulfate under the unlimed reference plot can be modeled if a reduced CEC and a free parameter function for alkalinity production are used. The sulfate desorption caused by liming can be explained by the model. It is concluded that sorbed sulfate contributes to the lime requirement of an acidified soil.
Treatment of Contaminated Soils with Organoclays to Reduce Leachable Pentachlorophenol
Authors: Brixie J. M. , Boyd S. A. 
Published: July 2010

AbstractThe toxicity characteristic leaching procedure (TCLP, method 1311) (USEPA, 1990) was used to evaluate the effectiveness of nine organoclays in reducing the leachability of pentachlorophenol (PCP) from three highly contaminated (3000–5000 mg kg−1) soils from wood treatment facilities. The soils differed in their PCP, oil and grease, and organic C contents. The organoclays were smectite exchanged with quaternary ammonium cations of the form [(CH3)3NR]+ or [(CH3)2NR2]+ where R is an aliphatic or aromatic hydrocarbon. A cement‐based solidification agent (Sorbond) was also added to the soil to evaluate its effects on the leachability of PCP. Organoclays with large (>C10) aliphatic R groups (organophilic organoclays) were compared with those with small aromatic or aliphatic groups (adsorptive organoclays). The adsorptive organoclays were much less effective than the organophilic clays in reducing PCP levels in the TCLP leachate. The organophilic clays dramatically reduced the leachability of PCP from all of the soils. The most effective clay tested was the dimethyldicocoammonium smectite; a 20% addition of this organoclay to the soil resulted in leachable PCP levels below the detection limit (0.2 mg L−1). The addition of Sorbond to the soil increased both the pH (from 4.95 to 12.00) and the PCP concentrations (from 6.8 to 100.8 mg L−1) in the leachate. However, when Sorbond was added with an organophilic clay, the PCP concentration was decreased below detection limits despite the increase in pH. These results demonstrate the potential effectiveness of organoclays for reducing the leaching of PCP from highly contaminated soils.
Atrazine Adsorption in Sandy Soils of Wisconsin
Authors: Seybold C. A. , McSweeney K. , Lowery B. 
Published: July 2010

AbstractPrevious studies have shown the mobility of atrazine [2‐chloro‐(4‐ethylamine)‐6‐(isopropylamino)‐s‐triazine] to be greatly different between characteristically similar sandy soils in Wisconsin. This study was conducted to determine if there are differences in atrazine adsorption capacity between sandy soils from Wisconsin, and if differences exist, what soil properties might be contributing to these differences. Atrazine distribution coefficients (Kd) were determined, and amounts of selected soil constituents (i.e., organic matter, clay, Fe oxides) were characterized by horizon in five sandy soils from different geographic regions of Wisconsin. The Kd values were strongly and significantly correlated to the OC content (r2 = 0.84). Also, clay contents in the lower subsoil horizons were significantly correlated to the Kd (r2 = 0.51). The organic fraction is the most important constituent for adsorption of atrazine in these sandy soils that contain small amounts of organic matter and clay. The Koc (Kd × 100/%OC) values varied considerably among soils and within soils with depth, and is attributed to differences in the ability of organic matter to adsorb atrazine and in contributions from clay minerals in the lower subsoil horizons. The pattern of Koc variation with depth is consistent across all soils. Surface soils that developed under forest have much larger Koc values than those that developed under prairie vegetation. We suggest that the larger atrazine adsorption capacity of organic matter in soils originally formed under forest vegetation contributes to the lower mobility of atrazine observed in these soils.
Utility Right‐of‐Way Contaminants: Polycyclic Aromatic Hydrocarbons
Authors: Wan Michael T. 
Published: July 2010

AbstractUtility right‐of‐way (ROW) ditches flowing into salmon (Oncorhynchus spp.) streams in the Lower Mainland and Vancouver Island of British Columbia, Canada, were sampled in 1990 and 1991 to determine the presence of polycyclic aromatic hydrocarbons (PAHs). Ditches of parklands, farmlands, and railway ROWs were also sampled to establish background and reference PAH concentrations. While PAHs were not detected in ditches of parklands, they were found in farmlands and in utility and railway ROW ditches. Concentrations of PAHs averaging 5.6 µg/L and 0.79 mg/kg were found in ditch water and sediments of farmlands, respectively. In utility ROW ditches, PAHs in water adjacent to treated poles averaged 551.7 µg/L, compared with a mean level of 23.2 µg/L 4 m downstream; in sediments collected from the same sites, the mean concentration of PAHs was 15 mg/kg and 3.3 mg/kg, respectively. Soils at the base of utility poles showed a mean PAH concentration of 3076 mg/kg, while wood chips/splinters from treated wood poles and railway ties contained about 62 000 mg/kg and 16 000 mg/kg PAHs, respectively. Levels of PAHs found in ditch water adjacent to treated poles did not exceed the 96‐h LC50 (lethal concentration of a chemical to 50% of the test fish population) of salmonids and aquatic invertebrate. The biological implications to these animals of exposure to low level PAH‐contaminated ditch sediments are discussed.
Comparison of Water Movement and Quality in Earthworm Burrows and Pan Lysimeters
Authors: Shipitalo M. J. , Edwards W. M. , Redmond C. E. 
Published: July 2010

AbstractAlthough a number of investigators have suggested that earthworm burrows can affect water movement and quality, little attempt has been made to directly measure their effect in the field. Using individual samplers, we monitored flow in Lumbricus terrestris L. burrows for 11 mo in adjacent no‐till and conventionally tilled watersheds used for the continuous production of corn (Zea mays L.). Tension‐free pan lysimeters were used to assess the composition and amount of bulk subsurface flow in each watershed and SrBr2·6H2O tracer was broadcast on a 25‐m2 area surrounding the samplers. In both watersheds the earthworm burrows functioned as preferential flow paths collecting more water, NO3‐N, Br, NH4‐N, and Sr than an equivalent area of soil overlying the pan lysimeters. Transport through the bulk soil was less in the tilled than in the no‐till watershed, and the burrows in the tilled watershed were less effective flow paths than those in the no‐till watershed, apparently due to disruption by tillage. Based on an estimated 1.6 million burrows (≥5‐mm diam.) per hectare, the amount of water, NO3‐N, Br, and Sr transported in these macropores was small, representing <5% of the totals measured using pan lysimeters. Data from burrow samplers and pan lysimeters installed in five farmer‐owned, no‐till fields under different soils and production practices supported the results obtained in the no‐till experimental watershed.
Estimating Herbicide Partition Coefficients from Electromagnetic Induction Measurements
Authors: Jaynes D. B. , Novak J. M. , Moorman T. B. , Cambardella C. A. 
Published: July 2010

AbstractA potential method for reducing pesticide leaching is to base application rates on the leaching potential of a specific chemical and soil combination. However, leaching is determined in part by the partitioning of the chemical between the soil and soil solution, which varies across a field. Standard methods of measuring the pesticide‐soil partitioning coefficient (Kd) are too expensive and slow for routine field mapping. Therefore, alternative methods for mapping Kd must be found if variable application methods are to be successful. We investigated the use of noncontacting electromagnetic induction measurements as surrogate measures of Kd. We measured the partition coefficient for atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine), apparent electrical conductivity by electromagnetic induction (Em), and mass fraction of soil organic carbon (foc) on a 250 by 250 m grid with a 25 m spacing. Both Kd and foc were lognormally distributed, while Em was poorly described by either a normal or lognormal distribution. Maps of the measured parameters showed similar spatial patterns, having low values on well‐drained soils and high values on poorly drained soils. Correlation coefficients between Kd and Em and Kd and foc were 0.575 and 0.686, and showed distinct spatial patterns. Spatial structure as indicated by correlograms indicated that each parameter was spatially dependent to distances of about 80 m. Simple relationships of Kd = 176 foc and Kd = exp(0.0336 Em) were found between the data. Maps of Kd estimated from foc or Em were similar to measured Kd, but more diffuse. Electromagnetic induction measurements failed to predict the observed high K6d values. The advantage of using Em measurements to map Kd is that it is a rapid, easy, and inexpensive method once it has been calibrated.
Measurement of Trichloroethylene Diffusion as a Function of Moisture Content in Sections of Gravity‐Drained Soil Columns
Authors: McCarthy Kathleen A. , Johnson Richard L. 
Published: July 2010

AbstractExperiments were conducted on discrete sections of gravity‐drained sand columns to determine the relationship between the effective diffusion coefficient of trichloroethylene and moisture content in variably saturated porous media. The columns were gravity drained to closely approximate field conditions and the moisture content within each column ranged from field capacity near the top to saturation near the bottom. Measured effective diffusion coefficients were compared with theoretical coefficients calculated using Millington's expression for tortuosity, modified to incorporate diffusion in both the gas and aqueous phases. Agreement between the measured and theoretical effective diffusion coefficients was good for all moisture contents investigated.
Release of Nitrogen and Phosphorus from Poultry Litter
Authors: Robinson J. S. , Sharpley A. N. 
Published: July 2010

AbstractIn areas of intensive poultry production, large amounts of litter produced are often applied as fertilizer to local agricultural land. To assess the agronomic and water quality implications of poultry litter applications, we quantified the effects of recurring, simulated rainfall (5 × 50‐min rainfalls of 2.54 cm h−1) alternated with different drying temperatures (4, 20, 30, and 35°C for 1 h) on the release of dissolved N and dissolved P from two types of poultry litter (pine bark shavingsand wheat straw‐based). Amounts of litter leached were equivalent to a 10 Mg ha−1 application, containing an average of 360 kg N ha−1 and 158 kg P ha−1. A total of 74 kg ha−1 NH4‐N, which accounted for >95% of the dissolved N, and 14 kg ha−1 inorganic P were released by the end of five rainfalls (averaged for the two types of poultry litter, and for all drying temperatures). Although the pattern of N and P release from litter was similar for all drying periods, the magnitude of losses was a function of drying temperature. The average portion of total N present in the litters released as NH4‐N during five rainfalls decreased from 22% for litter dried at 4°C to 18% for litter dried at 3S°C. This decrease was attributed to an increase in N volatilization at the higher temperature. Conversely, the portion of litter P released as dissolved inorganic P, increased from 8% at 4°C to 10% at 35°C. Thus, the influence of drying temperature on the release of N and P should be considered when determining the optimum timing of poultry litter application. It is suggested that the timing of poultry litter application should coincide with active periods of crop growth to combine maximum agronomic productivity with minimum edge‐of‐field losses of N and P to surface and groundwaters. As much as 60% of the N and 40% of the P released during the five rainfalls was lost during the first rainfall. This initial rapid N and P release stresses the importance of avoiding litter applications during periods of heavy rainfall.
Nutrient‐Loss Trends for Vegetable and Citrus Fields in West‐Central Florida: I. Nitrate
Authors: McNeal B. L. , Stanley C. D. , Graham W. D. , Gilreath P. R. , Downey D. , Creighton J. F. 
Published: July 2010

AbstractVegetable and citrus production in west‐central Florida is reportedly of considerable eutrophication hazard to local groundwater and surface‐water bodies, including a 33 000‐ha drinking‐water supply reservoir (Lake Manatee) near the coast of the Gulf of Mexico. Nitrate‐N levels were assessed for three vegetable‐production seasons during 1990 and 1991 using a combination of multilevel samplers into the shallow (surficial) aquifer beneath selected vegetable fields and citrus groves, coupled with piezometric wells around each field's periphery to assess direction and rate of groundwater flow. The NO3‐N concentrations beneath vegetable sites showed sizeable spikes (up to 130 mg L−1 NO3‐N), especially early in the season and at season's end, though almost exclusively at <1‐m depth. These concentrations did not persist, however, with the overwhelming majority of samples from most vegetable sites evidencing NO3‐N concentrations below 1 mg L−1. At citrus sites from the same area, NO3‐N concentrations in the surficial water table (located 2–4 m below the soil surface in this case) have evidenced high (20–40 mg NO3‐N L−1) and persistent levels throughout the entire sampling period. This zone of NO‐N enrichment commonly extends 2 to 3 m into the surficial aquifer before NO3‐N concentrations decline to <10 mg L−1 once more. Rates of lateral movement off‐site averaged 20 to 40 m yr−1 for the vegetable sites and 200 to 400 m yr−1 for the more undulating citrus sites. It is postulated that gaseous denitrification losses naturally remediate the periodic spikes in NO3‐N concentrations beneath the vegetable sites because of the high water tables maintained at such locations, whereas denitrification in the deep sands beneath typical citrus sites proceeds much more slowly due to such limitations as a soluble‐C energy source and/or a suitable microbial population. The results have implication with respect to shallow water table vs. deeply rooted crop‐production systems from the same geographic area, wherever such pairings may occur.