bluuebunny/crossref_metadata_2025 huggingface dataset:
Displacement of Soil Pore Water by Trichloroethylene
Authors: Wershaw R. L. , Aiken G. R. , Imbrigiotta T. E. , Goldberg M. C.
Published: July 2010

Dense nonaqueous phase liquids (DNAPLS) are important pollutants because of their widespread use as chemical and industrial solvents. An example of the pollution caused by the discharge of DNAPLs is found at the Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has been discharged directly into the unsaturated zone. This discharge has resulted in the formation of a plume of TCE‐contaminated water in the aquifer downgradient of the discharge. A zone of dark‐colored groundwater containing a high dissolved organic C content has been found near the point of discharge of the TCE. The colored‐water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic acids isolated from the colored‐waters plume, from water from a background well that has not been affected by the discharge of chlorinated solvents, and from soil pore water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compared. Nuclear magnetic resonance spectra of the fulvic acids from the colored waters and from the lysimeter are very similar, but are markedly different from the nuclear magnetic resonance spectrum of the fulvic acid from the background well. The three‐dimensional fluorescence spectrum and the DOC fractionation profile of the colored groundwater and the soil pore water are very similar to each other, but quite different from those of the background water. It is proposed from these observations that this colored water is soil pore water that has been displaced by a separate DNAPL liquid phase downward to the saturated zone.
Rainfall Simulator‐Grid Lysimeter System for Solute Transport Studies Using Large, Intact Soil Blocks
Authors: Bowman B. T. , Brunke R. R. , Reynolds W. D. , Wall G. J.
Published: July 2010

A grid lysimeter system and sample collection, containment, and storage techniques were developed for detailed laboratory studies of water and solute movement through intact soil blocks. This was done because existing designs and techniques had important deficiencies and were limited in their range of capabilities. Intact 46‐cm soil cubes were isolated, then contained within a polyurethane foam shell, which formed a stable, intimate soil bond, was impermeable to water and strong enough to support a large soil block, while sufficiently elastic to accommodate soil shrink‐swell with changing water content without rupturing. The soil blocks were instrumented with solution delivery, collection, and monitoring systems. A dripper‐based simulator delivered steady rainfall ranging from 4.8 to 30.0 mm h−1. The solution collection system was a 10 by 10 grid of cells (3.8 by 3.8 by 1.3 cm deep) milled into an aluminum block, which individually drained into collection tubes housed within a vacuum chamber. The collection grid permitted characterization of spatial and temporal water and solute movement through the block. The solution monitoring system consisted of side‐by‐side tensiometer pairs and time domain reflectometry (TDR) probes inserted horizontally through the foam shell at four depths in the block. As a partial test of the system, a bromide (Br−) tracer breakthough curve (saturated flow) was generated at a simulated rainfall rate of 19.2 mm h−1. Flow data indicated that 85% of the water in the block was bypassed by the Br−, and that >99% of the water flow passed through only 26% of the basal area of the block. The water flow pattern in the solution collector exhibited no evidence of preferential flow along the interface between the soil and the outer polyurethane shell. It was concluded that the rainfall simulator‐grid lysimeter system was operating effectively.
Herbaceous Layer and Soil Response to Experimental Acidification in a Central Appalachian Hardwood Forest
Authors: Gilliam Frank S. , Turrill Nicole L. , Aulick Staci D. , Evans Dan K. , Adams Mary Beth
Published: July 2010

The herbaceous layer (vascular plants ≤1 in in height) is an important component of forest ecosystems and a potentially sensitive vegetation stratum in response to acid deposition. This study tested several hypotheses concerning soil and herbaceous layer response to experimental acidification at the Fernow Experimental Forest in north‐central West Virginia. Fifteen circular sample plots (0.04 ha) were established in each of three watersheds: WS3 (an ≈ 20‐yr‐old watershed receiving acidification treatment with (NH4)2SO4), WS4 (>80‐yr‐old control), and WS7 (≈ 20‐yr‐old control). The herb layer was sampled intensively in 10 1‐m2 subplots within each sample plot, including determination of species composition, cover, and random biomass harvests. Harvested plant material was separated by species and analyzed for macronutrients, micronutrients, and Al. Soft was sampled from harvest subplots and analyzed for texture, pH, organic matter, and macro‐ and micronutrients. Few differences among watersheds for virtually all measured soil variables indicated minimal response of soil fertility to the acidification treatment. The herbaceous layer was also quite similar among watersheds with respect to cover‐biomass and species diversity; WS7, however, had ≈ 70% higher herb layer cover that both Ws3 and WS4, a result of the predominance of a few high‐cover fern species and attributable to the north‐facing aspect of WS7 vs. south‐facing aspects of WS3/WS4. There was a high degree of species similarity among watersheds, suggesting no shift in species composition in response to acidification. There was also minimal response of element concentrations to acidification, although Fe and Al exhibited evidence of increased uptake in WS3. We conclude that, contrary to our expectations, there has been little substantive response of the soil and herb layer to acidification, but hypothesize that herbaceous layer species may experience toxicity problems with increased mobility of Al and micronutrients in the future.
Using Gas Chromatography/Mass Spectroscopy Fingerprint Analyses to Document Process and Progress of Oil Degradation
Authors: Roques D. E. , Overton E. B. , Henry C. B.
Published: July 2010

One of the challenges in testing the effectiveness of bioremediation products is the lack of a standardized testing protocol. One requirement of any such evaluation is baseline and benchmark analyses of the oil and its degradation processes. The method described uses high resolution gas chromatography mass spectroscopy (GC/MS). This method has been adapted from oil fingerprinting techniques used by our group for oil spill response to major spills such as T/V Exxon Valdez and T/V Megaborg. It results in a high degree of chemical and spectral resolution from a single analysis that allows quantification of saturated hydrocarbons, polynuclear aromatic hydrocarbons (PAHs), sulfur heterocycles, and selected biomarkers such as hopanes and steranes. We demonstrate that high resolution GC/MS and compound specific analyses are a viable and efficient method of analyzing the extent and progress of oil bioremediation and that it should be possible to standardize the method for monitoring the biodegradation of oil. We also present data that show increased useful information obtained from this method and suggest possible future uses for this expanded database.
Biodegradation of Chromate‐Contaminated Groundwater by Reduction and Precipitation in Surface Soils
Authors: Losi M. E. , Amrhein C. , Frankenberger W. T.
Published: July 2010

A cost‐effective method is needed for removing chromate from cooling water blowdown, wastewater effluent, and contaminated groundwater. Experiments were conducted to determine the effectiveness of treating Cr‐contaminated water by using the water for irrigation, and that reduction of Cr(VI) to Cr(III) would occur in a soil amended with organic matter and irrigated to promote low oxidation/reduction status. The Cr(III) would then precipitate as oxides and hydroxides, and be immobilized and rendered plant unavailable. Samples of a field soil (mixed, thermic Typic Torripsamments) overlying a contaminated groundwater site were placed in pots and irrigated for 20 wk with water containing 1000 µg L−1 Cr(VI). Treatments included plants (alfalfa; Medicago sativa L.) vs. no plants, each at three organic matter Ioadings ‐ 0, 12, and 50 Mg ha−1 dried cattle manure (0, 5.5, and 21.8 g manure kg−1 soil). The drainage waters were collected weekly and analyzed for total Cr, Cr(VI), pH, dissolved O2, dissolved organic C, and electrical conductivity. The removal percentages of Cr(VI) from the enriched water ranged from 51 to 98% and increased with increasing organic matter loading. Chromium concentrations in the drainage water were consistently <50 µg L−1 in the organic‐amended soil. Daily irrigation yielded lower drainage water Cr concentrations than weekly irrigation (at a constant weekly volume) due to increased residence time of the water in the bioactive zone. Chromate adsorption accounted for <1% of the total immobilized Cr and the amount taken up by the alfalfa shoots was <0.5% of the total added. This method shows promise as a cost‐effective treatment for Cr‐contaminated groundwater.
Phytoremediation Potential of Thlaspi caerulescens and Bladder Campion for Zinc‐ and Cadmium‐Contaminated Soil
Authors: Brown S. L. , Chaney R. L. , Angle J. S. , Baker A. J. M.
Published: July 2010

Metal‐tolerant hyperaccumulator plants may be useful to phytoremediate contaminated soils. To evaluate agronomic management practices to maximize phytoremediation, two metallophytes, Thlaspi caerulescens J. and C. Presl (Zn hyperaccumulator) and bladder campion [Silene vulgaris (Moench) Garcke L.] (an indicator) were compared to ‘Rutgers’ tomato (Lycopersicon esculentum L.) in a pot study to assess Zn and Cd uptake patterns in relation to soil pH. Soils used for the study were gathered at three different sites in the vicinity of an old Zn smelter in Palmerton, PA, and contained 48 000, 4100, and 2100 mg kg−1 Zn and 1020, 37.4, and 35.2 mg kg−1 Cd, respectively. Each soil was adjusted to three pH levels ranging from 5.06 to 7.04. Thlaspi caerulescens showed much greater tolerance to the metals than the other plants (up to 18 455 mg kg−1 Zn and 1020 mg kg−1 Cd dry shoots without yield reduction) with metal stress apparent only in the low pH treatments of the two most contaminated soils. In all treatments except for the farm Soil (least contaminated) at pH 5.06, T. caerulescens had higher concentrations of both Zn and Cd than bladder campion and tomato. Thlaspi caerulescens was also more effective at translocating both Zn and Cd from soil to plant shoots. A variety of soil extractions were used to evaluate the correlation of shoot metal concentrations with quantitative measures of “available” soil metals. Concentrations of Cd measured in several common extractants (DTPA, water, 0.01 M Ca(NO3)2, and 1.0 M NH4NO3) were significantly correlated with Cd concentrations in tissue of each plant. Shoot Zn concentrations of bladder campion and tomato were significantly correlated with Zn extracted by the neutral salt extractants for all soils. For T. caerulescens, the neutral salt extractable Zn was significantly correlated with shoot Zn only in the two more contaminated soils. No extractant predicted shoot Zn concentration for T. caerulescens in the least contaminated soil.
Nitrogen and Carbon Mineralization Rates of Composted Manures Incubated in Soil
Authors: Hadas Aviva , Portnoy Rita
Published: July 2010

Rates of decomposition and inorganic N release from composted manures should be known and predictable on the basis of their composition for their proper use as a source of available N. Four composted cattle manures were analyzed for their inorganic N, soluble organic C and N, and total N and organic matter contents. The composts were incubated in soil for 32 wk at 30°C and 60% water‐holding capacity. Inorganic N and CO2 evolution were determined periodically. Inorganic N released from the composts after 32 wk ranged from 11 to 29% of their total N content, 2 to 12% of total N were initially inorganic, and 1 to 5% were soluble organic N. The rates of decomposition of the composts were computed by the simulation model NCSOIL by minimizing the deviation of the model output from the periodically measured CO2 and inorganic N release and by using the soluble and insoluble organic C and N contents of the composts as input. The soluble components decomposed before the end of the first week. The decomposition rate constant obtained for the insoluble components of three composts was 4 to 5 × 10−4 d−1, whereas for one compost it was 1 × 10−8 d−1, indicating that this compost was much more stable. To obtain universal rate constants that will fit any compost, components of the insoluble material must be better defined.
Kinetics of Ion Removal from an Iron‐Rich Industrial Coproduct: I. Chloride
Authors: Salingar Yigal , Sparks Donald L. , Ghodrati Masoud , Hendricks Gerald J.
Published: July 2010

An industrial TiO2 extraction process results in a Fe‐rich material (IRM) that contains substantial chlorides. Recent investigations showed that washed IRM may serve as a soil amendment for agricultural use. Yet, washing processes at the industrial production facility are currently problematic and costly, and it is essential to devise effective procedures for Cl removal. This study was conducted to determine the mechanism of Cl retention, and to ascertain whether the rate of Cl removal was governed by time‐dependent surface‐chemical kinetics or diffusion (transport)‐controlled kinetics. The IRM samples we used throughout the study were homogenous. It was physicochemically characterized and concentrations of heavy metals were determined. The IRM batch studies revealed negative Cl adsorption, even though its point of zero charge was 8.3. Column studies showed that 92% of the Cl was removed with the first pore volume. Additionally, the salt removal decreased the electrolyte concentration, caused dispersion, and, ultimately, lowered the hydraulic conductivity. Stirred‐flow kinetic studies established that Cl leaching was a function only of the total volume that flowed through the chamber, and that no chemical kinetics were involved.
Kinetics of Ion Removal from an Iron‐Rich Industrial Coproduct: II. Sulfate
Authors: Salingar Yigal , Sparks Donald L. , Pesek John D.
Published: July 2010

An iron‐rich material (IRM) contained copious quantities of salts, including Cl and SO4. A previous study on Cl removal hypothesized that SO4 played a major role in the chemistry of the IRM. Therefore, this study investigated the kinetics of SO4 removal from the IRM, which had a point of zero charge similar to those of some tropical soils. Stirred‐flow (SF) and column studies showed that SO4 removal was a time‐dependent chemical reaction(s). The SF technique facilitated modeling of the chemical kinetics of SO4 removal by providing a uniformly mixed system. The SO4 removal mechanism from the IRM to the ambient solution, in the SF system, was a zero‐order oxidation‐dissolution reaction of the Fe‐sulfide present as a minor constituent in the IRM. The computed value of the rate‐constant was 0.043 µmol min−1. In the column studies, the newly dissolved SO4 was present in the effluent, and was adsorbed on the IRM through a ligand (OH−) exchange mechanism. Calcium hydroxide dissolution, together with the SO4 adsorption, resulted in a pH increase with pore‐volume.
Kinetics of Ion Removal from an Iron‐Rich Industrial Coproduct: III. Manganese and Chromium
Authors: Salingar Yigal , Sparks Donald L. , Pesek John D.
Published: July 2010

An iron‐rich material (IRM) contained the potential soil and water pollutants Mn and Cr. Therefore, to assess the feasibility of using the IRM in agricultural and nonagricultural settings, this study was conducted to determine the processes and kinetics of Mn and Cr (total soluble metals) retention and removal from the IRM. This was accomplished by employing adsorption isotherms, column studies, and the stirred‐flow (SF) kinetic technique. Manganese adsorption conformed to the Langmuir equation and Cr adsorption was described by the Freundlich equation. The kinetic studies showed that indigenous Mn salts were depleted instantaneously via a volume‐dependent process. Both Mn and Cr in the IRM became solubilized while being processed at the industrial plant. But, unlike Mn, Cr was readsorbed by the IRM after the initial solubilization. This fraction of the Cr was desorbed rapidly, conforming to first‐order kinetics and yielding a rate‐constant of 0.56 min−1. After the rapid removal of some of the Mn and Cr, a steady‐state with wodginite may have governed Mn removal, and chromite may have controlled the Cr concentration, through zero‐order dissolution reactions. Both column and SF studies showed that the proportion of total soluble (dischargeable) Mn and Cr was small.
Natural Revegetation of 15 Abandoned Mine Land Sites in West Virginia
Authors: Skousen J. G. , Johnson C. D. , Garbutt K.
Published: July 2010

Fifteen AML sites ranging in age from 13 to 35 yr in northern West Virginia were selected from three surface‐mined coal beds (Pittsburgh, Freeport, and Kittanning) to evaluate plant invasion and establishment on disturbed sites. Three 10 m by 10 m plots were randomly located on each site, and cover, density, and stem diameter of all woody plant species were measured. Herbaceous and plant litter cover were also estimated in square‐meter quadrats within each 10‐m2 plot. Total tree cover was significantly different among sites on Pittsburgh and Kittanning coal mined sites, but not among Freeport sites. Among coal beds, Kittanning sites had the lowest tree cover (33% avg), Pittsburgh had an average of 67%, while Freeport sites had a multilayered tree cover averaging >100%. A total of 29 tree species were found on these sites. No tree species occurred on all 15 sites, but black cherry (Prunus serotina Ehrh.) and red maple (Acer rubrum L.) were found on 13 sites. Clustering produced three distinct plant communities including (i) an herbaceous community, (ii) a tree community dominated by red maple, and (iii) another tree community of primarily black birch (Betula lenta L.). Herbaceous communities were found on sites with soil pH > 5.0, while tree communities occurred on sites with pH < 5.0. On disturbed sites with high soil pH, herbaceous plants rapidly invaded and formed an almost complete cover. On low‐pH sites, the invasion of plant species from adjacent undisturbed sites was initiated in favorable microsites where minesoil or environmental conditions were ameliorated.
Modeling of Heavy Metal Transport in a Contaminated Soil
Authors: Černík Miroslav , Federer Peter , Borkovec Michal , Sticher Hans
Published: July 2010

Observed depth profiles in soils polluted by Zn and Cu that originate from a metal smelter are quantitatively interpreted by combining the production history of the smelter with established transport models. Using independent laboratory and field data, we were able to calculate the present depth profiles semiquantitatively by applying the pure convection model without parameter fitting. The agreement of the calculated depth profiles with the experimental data can be improved by including dispersion effects in the convection‐dispersion model or the stochastic convection model. For the latter model, the depth profiles were calculated analytically. These models were used to calculate the expected depth profiles in the future and to judge possible remediation strategies.
Passive Treatment of Acid Mine Drainage with Limestone
Authors: Hedin Robert S. , Watzlaf George R. , Nairn Robert W.
Published: July 2010

The water treatment performances of two anoxic limestone drains (ALDs) were evaluated. Anoxic limestone drains are buried beds of limestone that are intended to add bicarbonate alkalinity to flow‐through acid mine drainage. Both ALDs received mine water contaminated with Fe2+ (216–279 mg L−1) and Mn (41–51 mg L−1). Flow through the Howe Bridge ALD increased alkalinity by an average 128 mg L−1 (CaCO3 equivalent) and Ca by 52 mg L−1, while concentrations of Fe, K, Mg, Mn, Na, and SO2−4 were unchanged. The Morrison ALD increased alkalinity by an average 248 mg L−1 and Ca by 111 mg L−1. Concentrations of K, Mg, Mn, and SO2−4 all decreased by an average 17%, an effect attributed to dilution with uncontaminated water. Iron, which decreased by 30%, was partially retained within the Morrison ALD. Calcite dissolution was enhanced at both sites by high PCO2. Untreated mine waters at the Howe Bridge and Morrison sites had average calculated PCO2 values of 6.39 kPa (10−1.20 atm) and 9.24 kPa (10−1.04 atm), respectively. At both sites, concentrations of bicarbonate alkalinity stabilized at undersaturated values (SICalcite = 10−1.2 at Howe Bridge and 10−0.8 at Morrison) after flowing through approximately half of the limestone beds. Flow through the second half of each ALD had little additional effect on mine water chemistry. At the current rates of calcite solubilization, 17.9 kg d−1 CaCO3 at Howe Bridge and 2.7 kg d−1 CaCO3 at Morrison, the ALDs have theoretical effective lifetimes in excess of 20 yr. By significantly increasing alkalinity concentrations in the mine waters, both ALDs increased metal removal in downstream constructed wetlands.
Nonpoint‐Source Groundwater Contamination by 1,2,2‐Trichloropropane, A Trace Impurity in Soil Fumigant Formulations
Authors: Szeto S. Y. , Grove G. , Liebscher H. , Hii B. , Zebarth B. J.
Published: July 2010

Groundwater samples were collected from 60 piezometers and 23 domestic wells from March 1991 to April 1992 as part of a study to quantify NO−3 and pesticide contamination of the Abbotsford Aquifer, located in the lower Fraser Valley, southwestern British Columbia, Canada. A new contaminant, 1,2,2‐trichloropropane (1,2,2‐TCP), was detected and confirmed in 296 of the 514 samples by purge and trap GC/MS, and its concentration was determined in 150 of the samples collected between January and April 1992. The contaminant was detected in 34 (57%) of the piezometers sampled, and 10 (44%) of the domestic wells sampled. Mean 1,2,2‐TCP concentration (±1 SD) was 0.12 ± 0.11 µg L−1 in 123 piezometer samples and 0.14 ± 0.09 µg L−1 in 27 domestic well samples. The highest 1,2,2‐TCP concentrations measured were 0.62 and 0.32 µg L−1 for piezometers and domestic wells, respectively. The probable nonpoint sources of the contaminant are the synthetic pesticides, Telone (mixture of 1,3‐dichloropropene and 1,2‐dichloropropane) and Telone II (1,3‐dichloropropene), used to control pathogenic nematodes in raspberry (Rubus idaeus L.) production. Analyses of Telone and Telone II confirmed the presence of 1,2,2‐TCP as impurities in both products. The study demonstrates that an impurity present in pesticide formulations in trace quantities, which is persistent in soil and water, has the potential to result in significant groundwater contamination under the appropriate soil and climatic conditions.
Biodegradation Rate Enhancement of Hydrocarbons by an Oleophilic Fertilizer and a Rhamnolipid Biosurfactant
Authors: Churchill S. A. , Griffin R. A. , Jones L. P. , Churchill P. F.
Published: July 2010

The oleophilic fertilizer Inipol EAP 22 and a microbial biosurfactant (rhamnolipid) were investigated for their ability to increase the rate of biodegradation of aliphatic and aromatic hydrocarbons by pure bacterial cultures. Both Inipol EAP 22 and rhamnolipid were found to lower the surface tension of a phosphate buffered solution to 32 mN m−1. Each surfactant dramatically increased the apparent aqueous solubility of solid 2‐methylnaphthalene, and were capable of emulsifying liquid hydrocarbons. Biodegradation experiments were carried out with the TOL plasmid‐containing strain, Pseudomonas putida (ATCC30015); the OCT plasmid‐containing strain, P. oleovorans (ATCC29347); and an unknown naphthalene‐degrading strain (ATCC15075). Cells were grown under conditions where biodegradative enzymes were induced before their utilization. Model studies were conducted to investigate the ability of Inipol EAP 22 and rhamnolipid to enhance the rate of transport and uptake of hydrocarbons into bacterial cells, and to assess the impact that increasing the apparent aqueous solubility of hydrocarbons has on their rate of biodegradation. The extent of rate enhancement of compound mineralization resulting from surfactant addition was significantly greater for the sparingly soluble alkanes, hexadecane and octadecane, than for the more soluble aromatics, toluene and 2‐methylnaphthalene. The results suggest that increasing the bioavailability of hydrocarbons to bacteria may be a useful method to accelerate the rate of biodegradation at contaminated sites. Lastly, the data supports the hypothesis that surface‐active components present in the oleophilic fertilizer formulation, Inipol EAP 22, may have significantly contributed to the positive results reported in tests of remedial agent impact on bioremediation, which was used as a supplemental cleanup technology on Exxon Valdez crude oil contaminated Alaskan beaches.
Estimation of Humic‐Based Sorption Enthalpies from Nonlinear Isotherm Temperature Dependence: Theoretical Development and Application to Substituted Phenylureas
Authors: Spurlock F. C.
Published: July 2010

Thermodynamic assessments of organic chemical‐soil interactions are important for understanding various aspects of sorption phenomena, including isotherm nonlinearity. Expressions were derived here for calculating organic carbon based Freundlich nonlinear sorbed phase partial molar enthalpies (ΔH̄1) and entropies (ΔS̄1) from isotherm temperature dependence. It was shown that, in general, any changes in nonlinearity with temperature must be evaluated when estimating enthalpy effects from isotherm temperature dependence. The results were applied to nonlinear soil sorption data of three substituted phenylurea herbicides between 281 K and 297 K. The ΔH̄1 estimated at 289 K were found to range down to approximately −50 kJ mol−1, and were associated with negative ΔS̄1. Differential heats of sorption, which also include solution phase interactions, were ≈ 10 to 15 kJ mol−1 more exothermic than ΔH̄1. The ΔH̄1 were significantly less exothermic as sorbed phase concentrations increased. For diuron (1,1‐dimethyl‐3‐(3,4‐dichlorophenyl) urea), a compound that displays comparable solubility and octanol‐water partition coefficient as naphthalene, ΔH̄1 at higher concentrations were similar to values estimated for naphthalene (approximately −4 to + 10 kJ mol−1, calculated here from literature data), a nonpolar compound without polar functional groups. The data suggest that specific interactions between the phenylureas and soil organic matter moieties are dominant at low sorbed phase concentrations, but become less important relative to nonspecific London‐van der Waals forces as sorbed phase concentration increases. The urea isotherms are therefore nonlinear, with nonlinearity fundamentally related to the nature of substituted phenylurea sorbed phase interactions.
Dissipation and Distribution of Herbicides in the Soil Profile
Authors: Weed D. A. J. , Kanwar R. S. , Stoltenberg D. E. , Pfeiffer R. L.
Published: July 2010

The distribution and dissipation of alachlor [2‐chloro‐2′,6′‐diethyl‐N‐(methoxymethyl) acetanilide], atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5 triazine), and metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] in soil were studied in 1990, 1991, and 1992. Crop management practices included four tillage methods—chisel plow, moldboard plow, no‐till, and ridge‐till—and two crop rotations—continuous corn (Zea mays L.) and a corn‐soybean [Glycine max (L.) Merr.] rotation. All herbicides were broadcast‐spray applied with no incorporation. No‐till plots had the smallest amounts of alachlor and metribuzin, whereas ridge‐till plots had the smallest amounts of atrazine. Moldboard‐plow plots usually contained the highest amounts of all three herbicides, although ridge‐till plots had the highest metribuzin levels in 1992. These differences were seldom significant at the 0.05 level of probability, however. Throughout the growing season, 50 to 84% of the alachlor and metribuzin were retained in the top 10‐cm layer of soil, and at least 68% of the atrazine was retained in the top 20 cm. From 84 to 98% of the herbicide applied was lost each year, probably by microbial degradation and, for alachlor, by volatilization after application. First‐order half‐lives were 36 d for alachlor, 55 d for atrazine, and 32 d for metribuzin. A two‐compartment model better fitting the alachlor data returned a half‐life of 24 d for that herbicide.
Concurrent Evaluation of Agronomic, Economic, and Environmental Aspects of Trickle‐Irrigated Watermelon Production
Authors: Pier J. W. , Doerge T. A.
Published: July 2010

Reducing application rates of water and N fertilizers in irrigated cropping systems can lower the potential for N losses, but increases economic risk to producers. A data normalization method and an abstract spatial analysis procedure examined yield, net economic return and unaccounted for N from a subsurface, trickle‐irrigated watermelon [Citrullus lanatus (Thumb.) Matsum. & Nakai] cropping system in southern Arizona as a function of N and water inputs. Field research was conducted on a Casa Grande sandy loam (fine‐loamy, mixed, hyperthermic Typic Natrargid). A factorial design consisting of four levels of N (60, 216, 315, and 500 kg N ha−1) and three average soil water tensions (4, 7, and 17 kPa) resulted in a yield response surface. Watermelon marketable value and costs of water and N inputs were estimated to determine a net return response surface. A N mass balance was calculated by the difference method to estimate post harvest unaccounted for fertilizer N. Predicted maximum marketable yield was 102 Mg ha−1 at 7.2 kPa tension and 336 kg N ha−1. Predicted maximum net return was $10 819 ha−1 at 10.2 kPa tension and 256 kg applied N ha−1. Predicted maximum unaccounted for N was 300 kg N ha−1 at 4 kPa tension and 500 kg applied N ha−1. Normalization and summation of yield, net return and unaccounted for N response variables resulted in a predicted optimum response at 12.6 kPa and 178 kg N ha−1. The combined response variable was within 95% of this maximum value across the range of 10 to 16 kPa tension and 60 to 300 kg applied N ha−1. Similarly, spatial analysis of the three response variables indicated 7 to 17 kPa tension and 60 to 315 kg applied N ha−1 would result in yield and net return of >95% of the calculated maxima of marketable yield and net return, while limiting calculated NO3−‐N concentration in soil water draining below the root zone to <10 mg NO−3‐N L−1. These results suggest that data normalization and abstract spatial analysis are useful in concurrent evaluation of agronomic, economic, and environmental production criteria for subsurface trickle‐irrigated watermelon.
On‐Site Wastewater Treatment Using Unsaturated Absorbent Biofilters
Authors: Jowett E. Craig , McMaster Michaye L.
Published: July 2010

A new type of single‐pass aerobic biofilter is being developed as an alternative to the conventional septic tile bed and for treatment of wastewater in general. The Waterloo Biofilter uses absorbent filter media that combine long retention tunes, separate flowpaths for wastewater and air, and large surface areas, thereby enabling loading rates 10 times greater than that for solid particle filter media. Although absorbent sphagnum peat and coarse sand plug readily at loading rates of 50 to 80 cm d−1, absorbent plastic particles provide consistent treatment with no plugging problems. The latest field trial removes 97.8% BOD7, 96.1% TSS, and 99.5% fecal coliform bacteria with 12 to 16°C wastewater loaded at 49 cm d−1. Surge flows up to 204 cm d−1 over several days are handled with little effect on effluent quality. In laboratory column experiments, removal of fecal coliforms averages >99.99% at 80 cm d−1 loading, and >99.999% at 10 cm d−1 after a 10‐ to 14‐d acclimatization period. Ammonium is thoroughly oxidized to NO−3 with typically <2.5 mg L−1 NH4+‐N in the effluent. Overall treatment improves with forced air flow compared with natural convection. Cold influent and plugging by freezing are the main causes of poor treatment. A typical household would likely require a biofilter with 3.3‐m2 surface area in cold climates when flow is balanced, possibly less in warmer areas. This biofilter should also find general application in renovating polluted water, including water for domestic consumption in developing regions of the world.
Nutrient‐Loss Trends for Vegetable and Citrus Fields in West‐Central Florida: II. Phosphate
Authors: Stanley C. D. , McNeal B. L. , Gilreath P. R. , Creighton J. F. , Graham W. D. , Alverio G.
Published: July 2010

Vegetable and citrus production in west‐central Florida has come under suspicion as a hazard (with respect to NO3‐N and ortho‐P) to local groundwater and surface‐water bodies, including a 33 000‐ha drinking‐water supply reservoir near Bradenton in Manatee County. Using a combination of multilevel samplers in the shallow (surficial) aquifer beneath selected vegetable fields and citrus groves, coupled with piezometric wells around each field's periphery to assess depthintegrated solute concentrations and direction and rate of groundwater flow, ortho‐P levels have been assessed at 10 sites for three vegetable‐production seasons during 1990 and 1991. Some ortho‐P movement from vegetable production beds to surface waters and shallow groundwater appears likely, but ortho‐P concentrations also are elevated at a native range site that has not received P fertilizers, and in both man‐made and natural surface‐wateretention ponds plus nearby intermittent streams throughout the area. Naturally occurring phosphatic clays appear to be introducing considerable P into local shallow groundwater and associated surface‐water bodies. Regulatory strategies requiring sizeable retention ponds for tailwater‐return flow capture may be contributing to P loadings of the surface water, whenever pond construction intercepts phosphatic clay materials.
Reduction of Phosphorus in Runoff from Field‐Applied Poultry Litter Using Chemical Amendments
Authors: Shreve B. R. , Moore P. A. , Daniel T. C. , Edwards D. R. , Miller D. M.
Published: July 2010

Field applications of poultry litter at rates to meet forage N requirements normally result in an over‐application of P. Chemical amendments have the potential to reduce the solubility of manure P through precipitation and/or adsorption reactions. This study was conducted to determine the effects of two chemical amendments, alum (Al2 (SO4)3 · 14H2O) and ferrous sulfate (FeSO4 · 7H2O), on P concentrations and load in runoff and to evaluate the effects of amended litter on forage production. Litter was broadcast applied to fescue (Festuca arundinacea Schreb.) plots at 11.2 Mg ha−1 alone and in combination with alum or ferrous sulfate (1:5 amendment/litter). Rainfall simulators were used to produce three runoff events at 2, 9, and 16 d after litter application. Alum reduced the P concentrations in runoff by 87 and 63% of that from litter alone for the first and second runoff events, respectively, whereas ferrous sulfate decreased runoff P concentration by 77 and 48%, respectively. Both chemical amendments resulted in significant reductions (P < 0.05) in total P load for the first runoff event. Litter application significantly increased fescue yields, with total forage yield having the greatest response to alum‐amended litter. Mean forage yield with alum amended litter was 2358 kg ha−1, compared with a mean yield of 1847 kg ha−1 with litter alone. This was probably due to decreased NH3 volatilization with the alum treatment. The combination of decreased P loss and increased forage yields suggest that alum‐amended litter has substantial promise for use as an environmental and economic management tool in the poultry industry.
Speciation of Cadmium and Zinc with Application to Soil Solutions
Authors: Holm P. E. , Christensen T. H. , Tjell J. C. , McGrath S. P.
Published: July 2010

A two‐part method has been developed for determination of Cd and Zn species in 50‐mL soil solution samples containing low concentrations of Cd and Zn (1–10 μg Cd L−1 and 50–1000 μg Zn L−1). The method uses two cation exchange resins (Amberlite CG 120 and Chelex 100) in a batch‐column‐batch procedure and relies on analytical determinations of Cd and Zn by graphite furnace atomic absorption spectrophotometry. The first part (batch) of the method allows determination of free divalent Cd2+ and Zn2+. This part is experimentally sensitive to cation concentrations and ionic strength and these parameters should be controlled during the experimental procedures. However, it is shown that Cd and Zn concentrations and pH do not influence the method. Speciations performed on samples containing chloride and sulfate were in accordance with theoretical calculations. The second part (column‐batch) of the method operationally separates the complexed fraction into labile complexes, slowly labile complexes, and stable complexes. Chloro complexes were identified as labile complexes, while EDTA complexes were identified as stable complexes. The method works well with relatively small volumes of sample solutions and at low metal concentrations and may be useful in characterization of Cd and Zn in soil solutions.
Use of Calcium/Aluminum Ratios as Indicators of Stress in Forest Ecosystems
Authors: Cronan Christopher S. , Grigal David F.
Published: July 2010

The calcium/aluminum (Ca/Al) molar ratio of the soil solution provides a valuable measurement endpoint or ecological indicator for identification of approximate thresholds beyond which the risk of forest damage from Al stress and nutrient imbalances increases. The Ca/Al ratio can also be used as an indicator to assess forest ecosystem changes over time in response to acidic deposition, forest harvesting, or other processes contributing to acid soil infertility. Based on a critical review of literature on Al stress, we estimate that there is a 50:50 risk of adverse impacts on tree growth or nutrition when the soil solution Ca/Al ratio is as low as 1.0, a 75% risk when the soil solution ratio is as low as 0.5, and nearly a 100% risk when the soil solution Ca/Al molar ratio is as low as 0.2. The Ca/Al ratio of the soil solution can be corroborated with other complementary indices. Our analysis found that threshold conditions for potential forest impacts from Al stress are indicated by four successive measurement endpoints: (i) soil base saturation less than 15% of effective CEC; (ii) soil solution Ca/Al molar ratio ≤1.0 (for 50% risk); (iii) fine root tissue Ca/Al molar ratio ≤0.2 (for 50% risk); and (iv) a foliar tissue Ca/Al molar ratio ≤12.5 (for 50% risk). With appropriate precautions and caveats, these sequential indices based on the Ca/Al ratio provide a means of distinguishing site conditions where Al stress is likely to affect tree growth adversely.
Macroinvertebrate Communities in Headwater Streams Affected by Acidic Precipitation in the Central Appalachians
Authors: Griffith Michael B. , Perry Sue A. , Perry William B.
Published: July 2010

We collected quantitative macroinvertebrate samples monthly from September 1989 to October 1990 from four streams on the Allegheny Plateau of West Virginia that were characterized by different bedrock geology and streamwater pH. Mean pH was 4.3, 6.1, 6.0, and 7.5 in the four streams. We compared species and functional group composition of the benthic macroinvertebrate community in these streams to choose taxa that could be used as indicator species for differences in pH in bioassessment studies. The streams differed in species composition and abundance and several species were found that could be used as indicators for each of the levels of pH. Higher densities of Amphinemura sp., Leuctra sp., Euryophella funeralis, and Paracapnia angulata were characteristic of the stream with a pH of 4.3. Higher densities of Peltoperla arcuata and Wormaldia moesta were found in the streams with a pH of about 6.0. Gammarus minus, Baetis sp., Ephemerella dorothea, and Sweltsa sp. were found at higher densities in the stream with a pH of 7.5.
Occurrence of Pesticides in Prairie Lakes in Saskatchewan in Relation to Drought and Salinity
Authors: Donald David B. , Syrgiannis Jim
Published: July 2010

Prairie lakes are critical breeding, staging, and feeding habitat for a variety of shorebirds and waterfowl, and lower trophic levels in these habitats could be affected by agricultural pesticides. Following the severe drought of 1988 in Saskatchewan, concentration of 11 pesticides were determined in water, sediment, and zooplankton in 10 permanent and nine semipermanent lakes (those lakes that did not have standing water in 1988). The detection frequency for lindane, α‐HCH, and 2,4‐D in water was 57, 70, and 78%, respectively, with the maximum concentration 0.011, 0.004, and 0.43 µg/L, respectively. Triallate was detected in 39% of sediment samples and 54% of zooplankton samples at a maximum concentration of 31 and 10.2 µg/kg, respectively. When the lakes were grouped by salinity, detection frequencies of these pesticides were significantly higher in brackish lakes, which tended to be semipermanent (N = 6, mean specific conductance 3100 µS/cm) than in saline lakes, which tended to be permanent (N = 6, mean specific conductance 60 900 µS/cm). Other pesticides were detected in <20% of samples (diclofop‐methyl, atrazine, MPCA, dicamba, and bromoxynil) or not at all (trifuralin and picloram). With one exception, pesticide concentrations in these lakes were below those levels that might be deleterious to aquatic life, suggesting that these pesticides have not affected the food of avifauna at these lakes.
Uranium Isotopes Distribution in Soils at the Rocky Flats Plant, Colorado
Authors: Litaor M. Iggy
Published: July 2010

Soils east of Rocky Flats Plant (RTF) near Golden, CO, are contaminated with U as a result of past waste‐storage practices, accidental release of oils laden with U, and low‐level airborne emissions. A spatial analysis of three U isotopes was conducted to determine the concentration and distribution pattern of U contamination. Soils were sampled from 118 plots of 1.01‐ or 4.05‐ha by compositing 25 evenly spaced samples from the top 0.64 cm. Uranium‐234 activity ranged from 25.9 to 92.8 Bq kg−1, U‐235 activity ranged from 0.1 to 25.1 Bq kg−1, whereas U‐238 activity ranged from 30.7 kg−1 to 286 Bq kg−1. Geostatistical techniques were used to model the spatial dependency and construct isopleth maps showing U isotope distributions. Spatial correlation was not observed for U‐234. This implies that U‐234 is randomly distributed in the soil environment east of RFP. Uranium‐235 exhibited a spotty and localized concentration pattern with no clear relationship between known burial and spill sites, and the present distribution of U‐235 in the soils. Proposed wind‐dispersal mechanisms were not consistent with the spatial distribution of U isotopes. Most of the observed activities of U‐234 and U‐235 were well within the natural range of U isotopes in soils. The lack of similarity in spatial distribution between Pu‐239 + 240 and U isotopes probably resulted from the higher solubility and teachability of U isotopes compared with Pu‐239 + 240 in the soil system. Although U‐238 exhibited a pattern of localized spatial distribution, most of its observed activity was well within the natural range of U‐238 activity in soils.
Crop Residue Effects on the Leaching of Surface‐Applied Chemicals
Authors: Green J. D. , Horton Robert , Baker J. L.
Published: July 2010

Unknown effects of surface crop residues on interception, subsequent wash‐off, and movement of herbicides through soil are concerns associated with no‐tillage agriculture. To address these concerns, 12 undisturbed columns of a Clarion (fine‐loamy, mixed, mesic Typic Hapudoll) soil were obtained from a no‐till corn (Zea mays L.) field following harvest. Saturated hydraulic conductivity (Ksat), Cl− breakthrough, and drainable porosity were measured and used to group the columns into three blocks (high, medium, and low Ksat values). Corn residue was placed on the surface at rates of 0, 473, 946, and 1419 kg ha−1. Atrazine [6‐choloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] and CaCl2 solutions were surface applied to the columns, and 24 h later a sprinkling device was used to apply CaSO4 at a rate of 5 cm h−1. Effluent draining from the columns was collected and analyzed for Cl− and atrazine. Greater amounts of atrazine were recovered with the first 5.0 cm of drainage in the 100%‐residue columns than with the zero‐residue columns for the high and medium‐Ksat blocks. Differences in mass of atrazine recovered were greater in high‐Ksat than in medium‐Ksat columns. A trend indicating more recovery with less drainage for the high‐residue treatment was not apparent for the low‐Ksat columns. The time to peak atrazine concentrations decreased as crop residue levels increased for the higher‐Ksat columns, but not for the low‐Ksat columns. With 100% residue cover, the medium‐ and high‐Ksat columns demonstrated two peaks in Cl− and atrazine concentrations. This may indicate two pathways for the C− and atrazine movement through these columns; perhaps indicating the surface‐applied chemical that was not intercepted by crop residue was moving more slowly through the soil matrix.
Transport of Nitrate in Soils as Affected by Earthworm Activities
Authors: Li Yimin , Ghodrati Masoud
Published: July 2010

Earthworm (Lumbricus sp.) holes have long been recognized as an important conduit for water and solute transport in field soils. In this study we investigated preferential movement of NO3 through artificially induced earthworm holes and compared three commonly used solute transport models with respect to their ability to describe NO3 transport through the earthworm macropore system. Earthworms holes were created by introducing earthworms into uniformly packed soil columns of 20‐cm i.d. and 30‐ or 60‐cm long. After 8 wk of incubation, the columns were leached at a range of fluxes and NO3 breakthrough curves (BTCs) were determined. The columns also were traced with dyes to visualize the spatial distribution of the earthworm holes. The results showed that the earthworms completely altered the uniformity of the packed soil cores. The average saturated hydraulic conductivities of the earthworm hole columns (Ksm) increased 17.9‐ to 22.3‐folds compared with the control columns. Significant preferential movement of NO3 occurred in these columns even at relative fluxes as low as 0.014 Ksm. A nonlinear least squares program, CXTFIT, was used to fit three solute transport models to all BTCs. The physical nonequilibrium model (MIM) fitted the experimental data better than the convection‐dispersion equation (CDE) and the stochastic model (SM), while none of them was adequate to describe the data well.
Effects of Tall Fescue Endophyte Infestation on Relative Abundance of Small Mammals
Authors: Coley Alex B. , Fribourg Henry A. , Pelton Michael R. , Gwinn Kimberly D.
Published: July 2010

Small mammal populations were characterized nine times during six sampling periods on six plots in five different fields of tall fescue (Festuca arundinacea Schreb.) to determine differences in their abundance and species composition associated with the presence or absence of the endophytic fungus Acremonium coenophialum Morgan‐Jones & Gams. No differences were found in species richness (n = 4 for both types) between endophyte‐free (E−) plots and endophyte‐infested (E+) plots. Capture success, number of individuals, total captures, and recapture rates were more for E− plots than for E+ plots. All four species [eastern harvest mice (Reithrodontomys humulis Giglioli), short‐tailed shrews (Blarina brevicauda Gray), pine voles (Microtus pinetorum McMurtrie), and cotton rats (Sigmodon hispidus Say & Ord)] were captured more often in E− than in E+ plots. The diminished population densities of small mammals demonstrate the potential of E+ tall fescue as a permanent ground cover for waste disposal sites, orchards, tree farms, irrigation ditch banks, golf courses, and other residential, commercial, and industrial situations where burrowing activities of mammals may create human health hazards or financial burdens.