bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water Flow through Intact Soil Columns: Measurement and Simulation Using LEACHM
Authors: Smith W. N. , Reynolds W. D. , de Jong R. , Clemente R. S. , Topp E. 
Published: July 2010

AbstractAn evaluation of the water flow submodel, LEACHW, of the LEACHM solute transport model was conducted using profiles of volumetric water content, θ(z), and hydraulic head, H(z), measured under steady sated and near‐saturated flow conditions in two large, intact, soil columns. The hydraulic conductivity (K)‐water content (θ)‐pressure head (ψ) relationships, K‐θ‐ψ, required by LEACHW were obtained by fitting the Van Genuchten functions to measurements of sated hydraulic conductivity (Ks) and θ vs. ψ obtained: (i) using in‐situ TDR and tensiometer measurements, with the θ‐ψ data being collected during the initial column wetting; and (ii) using the traditional saturated flow‐desorption technique on intact soil core subsamples collected from the columns at the end of the experiment. The LEACHW model provided reasonably accurate predictions of the θ(z) and H(z) profiles, regardless of whether the in‐situ or soil core‐based K‐θ‐ψ relationships were used, and regardless of whether sated or near‐saturated flow occurred. The LEACHW predictions were substantially more accurate, however, when the K‐θ‐ψ relationships derived from the in‐situ measurements were used. It was concluded that the LEACHW model, coupled with independently measured K‐θ‐ψ functions, could provide reasonably accurate predictions of steady θ(z) and H(z) profiles in large, intact soil columns, regardless of whether the soil macropores are largely water‐conducting (sated flow) or largely nonwater‐conducting (near‐saturated flow). It also appears that in‐situ Ks and θ‐ψ measurements, with the θ‐ψ data collected during initial wetting, may provide more appropriate K‐θ‐ψ relationships for use in water and solute transport models than the traditional saturated flow‐desorption method using intact soil core subsamples.
Modeling pH‐Dependent Sulfate Adsorption in the Bs Horizons of Podzolized Soils
Authors: Gustafsson Jon Petter 
Published: July 2010

AbstractA model was developed that predicted the pool of adsorbed SO4 in the Bs horizons of northern Scandinavia as a function of pH and the solution SO4 concentration, assuming that 2 H+ are consumed for every SO2−4 adsorbed. To accomplish this, a sequential leach procedure with acid MgSO4 was used which facilitated the determination of SO4 adsorption capacity and the characterization of the adsorption isotherm. The Temkin equation showed the best fit within the range of SO4 concentrations used in this study. The variability between different soils in terms of adsorption capacities and isotherm slopes was modeled using linear and multiple regressions with other soil characteristics. Model results showed good agreement with other experimental observations in northern Scandinavia. The model, however, underestimated SO4 adsorption for soils from southern Scandinavia, which may be because of regional differences in, for example, adsorbent crystallinity. Furthermore, the results show that most pristine soils in northern Scandinavia retain 20 to 40% as much SO4 as they would retain if they were located in a severely acidified area. Therefore SO4 desorption following a decreasing atmospheric S deposition would only involve part of the adsorbed SO4. Only a small hysteresis effect was observed when the adsorption isotherm was compared to the desorption isotherm for one soil.
Phosphorus Leaching from Soils Containing Different Phosphorus Concentrations in the Broadbalk Experiment
Authors: Heckrath G. , Brookes P. C. , Poulton P. R. , Goulding K. W. T. 
Published: July 2010

AbstractTotal P (TP), total particulate P (TPP), dissolved reactive P (DRP), and dissolved organic P (DOP) were determined in waters from pipedrains (at 65‐cm depth) from the Broadbalk Experiment at Rothamsted. Soils that have received either no P, P in farmyard manure (about 40 kg P ha−1) or superphosphate (up to 35 kg P ha−1) annually for >150 yr, now contain 0.5 M NaHCO3‐extractable P concentrations (Olsen‐P) in the plow layer (0‐ to 23‐cm depth) between 5 and 100 mg kg−1 soil. Our aim was to determine if significant quantities of P could be detected in the drainage water and their relationship to soil P concentrations. On five occasions between October 1992 and January 1994, both TP and DRP from plots receiving superphosphate frequently exceeded 1 mg L−1 and were high compared with literature data. Ranging between 66 and 86% of TP, DRP was the largest fraction in drainage water. It remained low (<0.15 mg L−1) from plots below 60 mg Olsen‐P kg−1. There was then a rapid increase in DRP up to the maximum Olsen‐P concentration. A simple linear Split‐Line Model described this relationship very well for all drainage events. This implies that up to 60 mg Olsen‐P kg−1 soil (the change point), P was retained strongly in the plow layer. Above this, P losses in the drainage water were much more closely related to Olsen‐P than commonly suggested. The mechanisms could either be preferential flow or rapid transport of P in forms less susceptible to sorption but finally measured as DRP. The results suggest enhanced P losses through subsurface runoff on heavy soils, once a certain plow layer concentration of Olsen‐P is exceeded.
Effects of Domestic Wastewater Spray Irrigation on Denitrification Rates
Authors: Monnett G. T. , Reneau R. B. , Hagedorn C. 
Published: July 2010

AbstractSpray irrigation of domestic wastewater has potential as an effective on‐site wastewater treatment and disposal method for soils that have limited renovation capacity. Nitrogen removal via denitrification from spray irrigation can fluctuate due to the alternating aerobic and anaerobic conditions caused by irrigation frequency. The objectives of this study were (i) to determine the effect of domestic wastewater application rates and frequencies within a 24‐h period on nitrous oxide (N2O‐N) emissions from soil columns measured by the acetylene block technique, and (ii) to determine the influence of wastewater irrigation on the denitrification capacity of the soil. Treatments used two effluent application rates (1.25 and 2.5 cm wk−1) and three daily irrigation frequencies (1, 2, and 3 times d−1) and a no‐effluent control. Increased effluent application and splitting the effluent into two or three applications d−1 increased levels of N2O‐N emissions as compared with the control. Single daily doses of effluent produced low levels of N2O‐N emissions over the 24‐h measuring period, whereas more frequent applications produced rapid increases in N2O‐N emissions directly after effluent application. Gaseous losses of N averaged 5.3 and 26.2% of the applied N at the 1.25 and 2.5 cm wk−1 effluent loading rates, respectively. The denitrifying capacity of the soils was limited by both N and C. Maintaining effluent in the upper, more microbially active part of the soil column through split applications was important to N removal via denitrification.
Sorption of Nonionic Organic Compounds by Kentucky Bluegrass Leaves and Thatch
Authors: Lickfeldt D. W. , Branham B. E. 
Published: July 2010

AbstractSoil organic matter and plant litter layers are largely responsible for the immobility of organic compounds in agronomic environments. The objective of this research was to determine the sorption of nonionic organic compounds by turfgrass leaves and thatch and to correlate the sorption data with water solubilities (Sw) and octanol/water partition coefficients (Kow). Batch suspension experiments for phenanthrene, fenarimol (α‐(2‐chlorophenyl)‐α‐(4‐chlorophenyl)‐5‐pyrimidinemethanol), 1,2,4‐trichlorobenzene, ethoprop (o‐ethyl s,s‐dipropyl phosphorodithioate), and acetanilide (acetylaminobenzene) with Sw from 1 to 5405 mg L−1 were completed on Kentucky bluegrass (Poa pratensis L. cv. Touchdown) leaves and thatch. The resulting linear sorption isotherms (r2 > 0.922) for these organic compounds are consistent with a partitioning mechanism between water and leaves or thatch. The partition coefficients (K) for thatch ranged from 6.32 for acetanilide to 793 for phenanthrene. The K coefficients for leaves ranged from 3.53 for acetanilide to 2520 for phenanthrene. Sorption coefficients normalized for organic C content of the sorbent (Koc) were smaller for leaves and thatch than Koc values for soil organic C. The sorption coefficients for Kentucky bluegrass leaves had linear relationships with both the Sw and Kow of the organic compounds. The K values for Kentucky bluegrass leaves could be predicted from Sw and Kow, but values for thatch were highly variable. Both leaves and thatch were strong sorbents for organic compounds and should be expected to have a significant impact on the sorption and fate of chemicals applied to turf.
Biotechnology By‐Products as Sources of Nitrogen for Plants
Authors: Zhu B. , Tabatabai M. A. , Henning S. J. 
Published: July 2010

AbstractRecent developments in the biotechnology industries have resulted in production of large quantities of by‐products with potential uses as soil amendments and as sources of nutrients for plant growth and development. Many of these by‐products contain significant concentrations of organic and inorganic N that can be used by plants. This study evaluated, under greenhouse conditions, seven by‐products produced by four biotechnology industries in Iowa for their N‐supplying potentials to plants, and the results were compared with a conventional N fertilizer, urea‐ammonium nitrate (UAN). Corn (Zea mays L.) was grown on three Iowa surface soils treated at eight rates of N ranging from 0 to 500 mg of total N pot−1 (1 kg of soil) and harvested after 34 d. Results showed that both dry matter and N yield increased with increasing the rate of N in the by‐products applied to soil. Dry matter and N yield responses were similar among the three soils, but differed greatly among the by‐products studied. The by‐products FSL and FSG were superior N sources. Significant increases in dry matter and N yields were obtained by application of SMB, SS, Mycel, and HSOM. Among the seven by‐products studied, PC was a poor N source for corn. The by‐product HSOM was very acidic, and FSL and FSG contained high concentrations of NH+4. Addition of these by‐products to soils decreased the soil pH with increasing application rate. Results showed that some biotechnology by‐products are potential sources of N for plants and are useful as soil amendments.
Methyl Bromide Diffusion and Emission through Soil Columns under Various Management Techniques
Authors: Jin Yan , Jury William A. 
Published: July 2010

AbstractThe proposed phaseout of methyl bromide (MeBr) in 2001, while undertaken for environmental reasons, has important economic implications. At the present time, very little is known about how much MeBr escapes from fumigated soils into the atmosphere, or about methods for reducing this loss in an economically feasible manner. In this study we report the results of a series of experiments on MeBr diffusion and emission through soil columns under various management techniques. Column experiments were conducted to evaluate the effectiveness of commonly used polyethylene films in preventing MeBr emission into the atmosphere, and were analyzed with a mathematical model to estimate the soil gas diffusion coefficient (Dsg) and the mass transfer coefficients (h) for different polyethylene films. Additional experiments were then conducted to evaluate the effect of adding various amounts of irrigation water after injection and tarping on total MeBr emission into the atmosphere. The films were found to be only marginally effective in preventing MeBr emission from fumigated soils, while irrigating and then covering the soil with the film was much more effective in reducing MeBr loss.
Phosphorus Status of Forest and Agricultural Soils from a Watershed of High Animal Density
Authors: Simard R. R. , Cluis D. , Gangbazo G. , Beauchemin S. 
Published: July 2010

AbstractThe objective of this work was to study the impact of animal density on P status in soils from the Beaurivage River Watershed, Quebec, Canada. Twenty‐five samples from A, B, and C horizons from the five most representative soil series were taken from sites under forest, hay fields of dairy farms, and farms with a known surplus of on‐farm manure N (SN). Profiles were characterized for water‐soluble P (Pw), Mehlich‐3 extractable P (M3P), and fractions. The Pw was 3.6 times larger in agricultural than in forest soils in the A horizon. Excessive amounts of 66.5 mg kg−1 of M3P and of 95 mg kg−1 Resin‐P were found in the plow layer of agricultural soils and M3P was increased, on average, by 10 mg kg−1 in the C horizon compared with forest soils. The accumulation of added P has lead to an increase in labile (Resin + NaHCO3 + NaOH‐Po) P pools in the A horizon, whereas the resilient (total labile P) pools were the major sinks in B and C horizons. For SN farms, total P was increased by 435 mg kg−1 in the A, 86 mg kg−1 in B, and by 141 mg kg−1 in the C horizon compared with forest soils. Dairy farms soils had labile P contents similar to those from SN farms but were less enriched in resilient‐Pi forms. The observed large P loads in surface horizons and Pw increases in the subsoil of the agricultural soils probably contribute to the contamination of surface waters in this watershed.
On the Use of Virus Transport Modeling for Determining Regulatory Compliance
Authors: Yates Marylynn V. , Jury William A. 
Published: July 2010

AbstractThe U.S. Environmental Protection Agency (USEPA) has developed a draft Ground Water Disinfection Rule (GWDR) proposing that all public water systems using groundwater must disinfect the source water from each of its wells unless the wells meet one of the “natural disinfection” criteria they have developed or the system qualifies for a variance. A water utility that wished to avoid chemical or physical disinfection of its well water and did not meet the prescribed horizontal or vertical setback distances would have the option of using a virus transport model to determine whether there was adequate “natural disinfection” in their system. We think that this procedure is unwise, because there is enormous uncertainty in the estimates of the parameters required by the transport model. This uncertainty is amplified nonlinearly into the model prediction of maximum virus concentration the USEPA wishes to use as the basis for regulatory decisions. For typical levels of uncertainty in the input parameters, we predict that the concentration uncertainty will span many orders of magnitude, rendering model estimates of natural disinfection useless for regulatory purposes.
Contaminant Release from Solidified Radioactive Wastes Buried in Unsaturated Sediments: Lysimeter Study
Authors: Jones T. L. , Serne R. J. 
Published: July 2010

AbstractA lysimeter facility has been used since 1984 to monitor the leaching of buried waste forms under natural, arid conditions. The facility includes 10 bare‐soil lysimeters (183 cm diam. by 305 cm deep) containing buried waste forms solidified with Portland III cement, masonry cement, bitumen, and vinyl‐ester styrene. From 1984 through 1992, an average of 45 cm of water (27% of area precipitation) have leached through the lysimeters. To date, tritium, 60Co, and 137Cs have been identified in the lysimeter leachate samples. From 1984 through 1992, >4000 µCi of tritium, representing 76 and 71% of inventory (not decay corrected), have been leached from the two waste forms containing tritium. Cobalt‐60 (<0.1% of original Co inventories) has been found in the leachate from each of all six of the waste forms that originally contained >1 mCi of inventory. Mobile Co is believed to be chelated with organic compounds, such as EDTA, present in the waste. Trace amounts of 137Cs have occasionally been identified in leachate from two waste forms since 1991. Qualitatively, the field leaching results confirm laboratory studies, suggesting that tritium is readily leached from cement, and that 60Co is generally leached more from cement than from vinyl‐ester styrene. These data suggest that empirical source‐term models should predict leaching based on the amount of water flowing past the waste form, not based on time.
Remediation of Acid Soils by Using Alkaline Biosolids
Authors: Sloan J. J. , Basta N. T. 
Published: July 2010

AbstractAlkaline biosolids may be suitable as a liming amendment for acid soils. The efficacy of two alkaline biosolids, lime‐stabilized sewage sludge (LS) and N‐Viro Soil (NV), for remediating soil acidity and Al toxicity in strongly acid soils were evaluated. For comparison, soils were also treated with unlimed anaerobically digested sewage sludge (SS) and agricultural lime (L). Three acid soils were amended with LS, NV, SS, and L and incubated at 25°C. Soil solution was extracted at 1, 30, 90, and 180 d incubation and analyzed for pH, electrical conductivity (EC), dissolved organic carbon (DOC), Al, Mn, Ca, Mg, Na, K, F, Cl, PO4, NO3, and SO4. In general, soil pH increased linearly with amendment rate for all soils and all amendments. The magnitude of increase in soil pH after 6 mo for the four amendments followed the order L ≃ NV>LS>>SS. All amendments decreased soluble Al, but lime‐containing amendments (LS, NV, and L) decreased soluble Al below detection limits (<0.4 mmol L−1). The largest decreases in exchangeable Al were associated with lime‐containing amendments. Lime‐containing amendments reduced soluble Mn but unlimed sewage sludge had no effect on soil solution Mn. Soluble Al speciation using MINTEQA2 showed that all rates of lime‐containing amendments (LS, NV, and L) decreased Al3+ activity to nontoxic levels (<10 mmol L−1). Saturation indices indicated sewage sludge amendments may have resulted in precipitation of Al as alunite [KAl3(OH)6(SO4)2·H2O]. Although SS decreased phytoavailable Al, alkaline biosolids caused greater reductions in potentially phytotoxic Al than nonalkaline biosolids (SS).
Effect of Aliphatic Nonaqueous Phase Liquids on Naphthalene Biodegradation in Multiphase Systems
Authors: Gamerdinger A. P. , Achin R. S. , Traxler R. W. 
Published: July 2010

AbstractBiodegradation of naphthalene by a Coryneform bacterium was examined in multiphase aqueous slurry systems containing a nonaqueous phase liquid (NAPL). The evolution of 14CO2 provided an index of biodegradation under aerobic conditions. The effect of NAPL hydrophobicity was evaluated by considering a homologous series of n‐alkanes (C6–C16). Experiments were conducted in NAPL‐water and soil‐NAPL‐water systems where the inoculum was pre‐incubated with a sandy aquifer material. Relative to aqueous systems, conversion to CO2 increased in the presence of decane, dodecane, and hexadecane. Biodegradation was apparent, but decreased in the presence of octane, and was negligible in the presence of hexane. Thus biodegradation was sustained in multiphase systems where log Kow of the NAPL was >5, and was inhibited in systems where the log Kow of the NAPL was <4. Naphthalene partitioning between water and each of the NAPLs was similar, indicating that the observed differences in biodegradation among the homologous series were not due to differences in naphthalene distribution. Naphthalene sorption to the sandy aquifer material was minimal and the aquifer material did not significantly modify biodegradation. Mineralization rates were reduced in multiphase systems when compared with aqueous systems; CO2 production curves were described with a first‐order kinetic model. Reduced mineralization rates in soil‐NAPL‐water systems can be explained by the lower aqueous phase concentration. This was not the case in the NAPL‐water system, suggesting a direct effect of the NAPL on the bacteria.
Zinc Concentrations in Groundwater at Different Scales
Authors: Stein A. , Varekamp C. , van Egmond C. , van Zoest R. 
Published: July 2010

AbstractAn extensive database of the concentrations of heavy metals in phreatic groundwater was used to study the spatial variability of Zn. This paper focused on the Zn concentrations in relation to soil survey variables. Three scales of observation were distinguished: provincial level (1:1 000 000), city level (1:100 000), and parcel level (1:10 000). Use of classification of the study area based on digitized maps was investigated. A Geographic Information System (GIS) was used to overlay and investigate different sources of information. The variance of Zn in groundwater decreased by 50% when going from provincial to parcel scale. The results indicate that Zn variation is dominated by short‐range variation. Significant differences in Zn contents were found for Zn grouped by seepage (infiltration vs. deep seepage) and geology. Classification according to seepage yielded reduced coefficients of variation within several seepage class. At the city level, significant differences in Zn were found for soil and land use. The sample semivariogram showed that Zn exhibits a spatial dependence different from that of electrical conductivity (EC) and pH. This may be explained by the distribution of soil groups on the soil map of scale 1:50 000. At the most detailed level, no significant differences in Zn were found between soil units or land use categories. The distinction of significantly different concentrations allows a flexible setting of background threshold values.
Chromosomal Damage Induced by Herbicide Contamination at Concentrations Observed in Public Water Supplies
Authors: Biradar D. P. , Rayburn A. Lane 
Published: July 2010

AbstractHerbicide contamination of natural resources, specifically groundwater, has drawn considerable public attention in recent years. Although deleterious effects of herbicides at large dosages have been well documented, information is lacking about the possible effects of herbicide levels that are found in public water supplies. Chromosomal damage is examined by flow cytometry on Chinese hamster ovary (CHO) cells that are exposed to three herbicides (atrazine, simazine, and bentazon) at concentrations deemed safe by the U.S. Environmental Protection Agency (USEPA) for drinking water. A known clastogen (ara‐C) is also included as a reference for comparing the magnitude of chromosomal damage caused by herbicides. Chromosomal damage was assessed by measuring the coefficient of variation (CV) and percent chromosomes present in the larger chromosome distribution peaks. Exposure to atrazine (6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine) increased the CV of the largest chromosome distribution peak at concentrations considered safe by the USEPA. Chromosomes exposed to both simazine (6‐chloro‐N,N′‐diethyl‐1,3,5‐triazine‐2,4‐diamine) and bentazon (3‐(1‐methylethyl)‐(1H)‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide) did not exhibit chromosomal damage. Further analyses carried out on atrazine concentrations about equal to levels found in public water supplies revealed the potential of atrazine to induce chromosome breakages in CHO cells. Atrazine concentrations that were manyfold greater than the contamination limits exhibited a true clastogenic nature like ara‐C. The results provide evidence for further investigations as to the potential health risk of consuming water contaminated with atrazine.