bluuebunny/crossref_metadata_2025 huggingface dataset:
Lead Levels in Blood from Cattle Residing near a Lead Smelter
Authors: Neuman D.R. , Dollhopf D.J.
Published: July 2010

Concentrations of Pb in whole blood from 222 cattle (Bos tarus L.) representing nine herds were determined. Lead blood levels were significantly (P ≤ 0.05) elevated for herds near a primary lead smelter compared to a background herd. Herd Pb blood levels were significantly correlated to distance from the smelter (r = −0.86), and to soil Pb concentrations (r = 0.96). They were also moderately correlated (r = 0.61) to vegetation Pb levels. Soil may be more important than forage as a source of Pb for these cattle. Immature cattle, less than 1 yr old, had higher (P ≤ 0.05) Pb blood levels than mature cattle. A total of 15 animals (all immature) exhibited Pb blood values above 35 µg dL−1. Twenty‐one animals had elevated (22–35 µg dL−1) Pb blood levels. Most cattle (80%) tested near the smelter and all cattle from the background herd had Pb blood levels in the normal diagnostic range (1–21 µg dL−1).
Red Spruce Response to Ozone and Cloudwater after Three Years Exposure
Authors: Thornton F. C. , Pier P. A. , McDuffie C.
Published: July 2010

This study reports on the results of a 3‐yr study conducted at a high elevation site in the southern Appalachians to determine if cloudwater and ozone (O3) adversely affect the growth of red spruce seedlings (Picea rubens Sarg.). Field chambers were established at Whitetop Mountain, VA (elevation 1689 m), in 1988. Three replicate chamber treatments were constructed to produce the following treatments: (i) exclusion of clouds and O3 (COE), (ii) ambient O3 with clouds removed (CE), and (iii) exposure to both clouds and O3 (CC). Ambient air plots (AA) were also included in order to assess possible chamber effects. Potted native seedlings from the surrounding forest and seedlings grown from seed collected in the Great Smoky Mountains National Park (GSM seedlings) were used in the study. After 3 yr, seedlings were impacted little by the reduction in pollution levels within the CE and COE chambers. No differences in seedling diameter growth were found for either seedling type, and height growth differences that were detected indicated more height growth in treatments with ambient O3 and cloudwater. Minimal biomass effects were also found. Increased nutrient leaching of needle Ca and Mg was observed in cloudwater treatments, but needle concentrations were not reduced to deficiency levels. Removal of both cloudwater and O3 (COE) did not enhance photosynthesis (Ps) rates for native or GSM seedlings. However, Ps of seedlings in which only cloudwater was removed (CE) was lower in 1‐yr‐old needles (C + 1) of native and GSM seedlings, and in 2‐yr‐old needles (C + 2) of native seedlings. These lower Ps rates of CE seedlings were correlated with lower needle N concentrations, indicating that cloudwater NO3− and NH4+ may have provided a fertilizer effect within AA and CC treatments. Respiration of current year needles of native seedlings was not affected by treatments; however, respiration was lower in older needles (C + 1 and C +2) in which O3 and cloudwater were removed (CE and COE).
Polynuclear Aromatic Hydrocarbon Uptake by Carrots Grown in Sludge‐Amended Soil
Authors: Wild S.R. , Jones K.C.
Published: July 2010

The uptake of polynuclear aromatic hydrocarbons (PAHs) from sewage sludge‐amended soils by carrots (Daucus carota) was investigated. Carrots were grown in control soils and soils amended with three sludge application rates, 15, 55, and 180 t/ha. Applied sludge contained 17.2 mg ΣPAH/kg, a concentration typical for a sludge derived from a rural area. Carrot foliage, root peels and root cores were analyzed for 15 PAH compounds. Carrots foliage PAH concentrations were unaffected by sludge applications (PAH loadings), but root peel PAH concentrations increased to a plateau concentration with increasing soil PAH levels. Low molecular weight PAH compounds dominated individual components of the ΣPAH load in the root tissues. The PAH concentrations detected in the root peels were all significantly lower than in the foliage, which receives PAH inputs from the atmosphere. Carrot core ΣPAR concentrations were unaffected by sludge application, implying little or no transfer of PAHs from the peels to the core. About 70% of the PAH burden found in carrots was associated with the peels. Fresh weight carrot core concentrations were all <4.2 µg/kg. Overall, this investigation suggests that the risks posed to human health by PAHs applied in sewage sludge to arable soils are minimal.
Selenium in Kesterson Reservoir Ephemeral Pools Formed by Groundwater Rise: II. Laboratory Experiments
Authors: Poister David , Tokunaga Tetsu K.
Published: July 2010

The formation of seleniferous ephemeral pools that result from shallow water table rise through seleniferous soils was studied in laboratory columns of soils from Kesterson Reservoir, Merced County, California. Variables included in the column experiments included the depth interval of the soils, the rate of shallow water table rise and temperature. The columns were packed with either surface (0–0.15 m) soils (with and without the original salt crust), or subsurface soils (0.15–0.30 m) sampled from the southwest corner of Pond 1, Kesterson Reservoir. Controlled inputs of nonseleniferous, saline water through the bottoms of the columns provided water table rise rates of 3, 10 and 30 mm d−1. The soil columns were maintained at either room temperature (≈25°C) or 5°C. The amount of Se transported from the soils into the overlying ponding waters was proportional to the water‐extractable soil Se content, and was positively correlated with the rate of water table rise. The 5°C experiments resulted in greater Se transfers into the ponding waters in the columns subjected to 10 and 30 mm d−1 rates of water table rise (relative to comparable room temperature columns), while the reverse effect was observed with 3 mm d−1 columns.
Chemical Properties of Municipal Solid Waste Composts
Authors: He Xin‐Tao , Traina Sam J. , Logan Terry J.
Published: July 2010

Composting municipal solid waste (MSW) is becoming increasingly recognized as a viable and economical method for waste management in both Europe and the USA. Composting has advantages over land‐filling and incineration because of lower operational costs, less environmental pollution, and beneficial use of the end product. There are, however, some uncertanties about potential health hazards resulting from excessive MSW compost application to agricultural lands. This article reviews currently available literature on chemical properties of MSW compost and the effects of compost application on soils. It is concluded that the positive effects resulting from compost application far outweigh the negative effects, but more research is needed on a wide range of MSW composts with more precise determination of the fate of MSW compost‐applied trace elements in the environment.
Mobility of Heavy Metals in Urban Waste‐Amended Soils
Authors: Giusquiani Pier Lodovico , Gigliotti Giovanni , Businelli Daniela
Published: July 2010

A soil column study was conducted to assess the vertical movement of certain heavy metals in soils amended with urban waste compost (90 t ha−1). The effect of the complexing capacity of water soluble organic matter from compost on metal mobility has been previously reported. The results of this investigation demonstrate the enhanced levels of Cu, Zn, Ni, and Cr eluted from 50‐cm soil columns when compost is added to a Fluventic Xerochrept clay‐loamy, mixed, mesic and a Typic Xerochrept, fine sandy‐loamy, mixed, mesic. The increase in these metal concentrations is greater in sandy‐loam soil than in clay‐loam. The water soluble organic fraction of the compost has minimal impact on the metals concentration. Seventy to eighty percent of the water‐soluble organic fraction was retained in the upper 10‐cm layer of soils, with only 5% eluted from clay‐loam soil and 10% from the sandy‐loam.
Effect of Water Potential, Temperature, and Soil Microbial Activity on Release of Starch‐Encapsulated Atrazine and Alachlor
Authors: Wienhold Brian J. , Gish Timothy J.
Published: July 2010

Starch encapsulation has been proposed as a method for controlling the rate at which pesticides are released into the soil. Relatively little is known about what environmental factors influence controlled release. A series of laboratory studies were initiated to improve our understanding of how water potential, temperature, and soil microbial activity influence rate of release of starch‐encapsulated atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine) and alachlor (2‐chloro‐2′,6′‐diethyl‐N‐(methoxymethyl)‐acetanilide). Water potential, imposed using polyethylene glycol, significantly influenced swelling of the starch matrix and rate of release of both herbicides. At a water potential of 0 MPa, complete release required 21 d for atrazine and 7 d for alachlor. As water potential declined, so did rate of release. At a water potential of −1.5 MPa, less than 50% of the encapsulated atrazine and less than 80% of the encapsulated alachlor had diffused out of the starch matrix after 28 d. Temperature also influenced rate of release of both herbicides. At 35°C nearly three times more atrazine and two times more alachlor was released from starch granules than at 15°C at all sampling times. Soil microbes increase the rate of release. After 21 d there was a twofold increase in the percentage of atrazine released from starch granules applied to nonsterile soil compared with granules applied to sterile soil. Effect of soil microbes on rate of alachlor release was apparent only at early times. After 5 d there was a 20% increase in the percentage of alachlor released from starch granules when microbes were present compared with release from starch granules applied to sterile soil. After 14 d essentially all of the alachlor had been released from starch granules applied to either sterile or nonsterile soil. The different influences that water potential, temperature, and soil microbes have on rate of release between atrazine and alachlor are likely due to differences in water solubility of atrazine (30 mg L−1) and alachlor (240 mg L−1).
Mineralization of Sediment Organic Matter under Anoxic Conditions
Authors: Gale P.M. , Reddy K.R. , Graetz D.A.
Published: July 2010

Organic matter steadily accumulates in eutrophic lakes as a result of deposition of detrital tissue from algae and aquatic macrophytes and the slow rate of anaerobic decomposition. The rate of organic matter decomposition is affected by the nature of the sediment C (electron donor) and supply of electron acceptors. Batch incubation experiments were conducted to determine the rate and extent of organic matter decomposition in bottom sediments under anoxic conditions. Sediment samples from three distinct horizons were collected from a hypereutrophic lake (Lake Apopka, located in central Florida), which included the surface unconsolidated flocculent material (UCF), an underlying consolidated flocculent material (CF) and native peat sediment. Sediment samples were incubated in serum bottles at 15, 25, and 35°C in the dark for 534 d. Periodically, the serum bottle head space was analyzed for CO2 and CH4 produced during decomposition. At selected time intervals, the sediments were analyzed for water soluble organic C, pH, exchangeable NH4‐N, and soluble reactive P. First‐order rate constants for C mineralization (defined as the sum of gaseous C evolved and soluble C species produced) ranged from 6.7 × 10−4 d−1 for the UCF sediment incubated at 35°C to 8.2 × 10−6 d−1 for the peat sediments incubated at 15°C. Two phases of organic C decomposition were observed in the UCF and CF sediments while, decomposition in the peat sediments was characterized by only one phase. The UCF sediment, composed of recently deposited detrital organic matter, was found to be the most labile. However, under current experimental conditions, only 8.6% of the UCF sediment organic C was mineralized to CO2 and CH4. The biodegradability of sediment organic C ranked in the order UCF > CF > peat. Net mineralization of N and P was observed in all of the sediment samples (with the exception of the CF samples incubated at 15°C). The N and P mineralized during the decomposition of UCF organic matter may contribute to the nutrient load of the overlying water column.
Groundwater Nitrate and Denitrification in a Coastal Plain Riparian Forest
Authors: Lowrance Richard
Published: July 2010

Mechanisms of nitrate (NO3) removal from groundwater in riparian forests are poorly understood. This study was conducted in the Georgia coastal plain to: (i) determine changes in NO3 and Cl concentrations within shallow groundwater moving from a row‐crop field to a stream; (ii) determine the spatial and temporal distribution of denitrifiration potential relative to changes in NO3 concentrations; and (iii) determine whether NO3 or C supply was limiting denitrification potential. Nitrate and Cl concentrations in groundwater were measured biweekly or monthly for October 1988 through May 1990. Denitrification potentials, indicated by the denitrification enzyme assay, were measured bimonthly from October 1988 through October 1989. Modified potential measurements, lacking either NO3, C, or both, were also performed bimonthly. Both NO3 and NO3/Cl ratios in groundwater decreased by a factor of 7 to 9 in the first 10 m of forest. Within the next 40 m of forest, mean NO3 concentration decreased from 1.80 to 0.81 mg NO3‐N L−1. Denitrifiration potential was more than two orders of magnitude higher in the top 10 cm of soil than in the top 10 cm of the shallow aquifer. Denitrification potential was consistently highest in surface soil nearest the field and nearest the stream and was limited by NO3 availability in all surface soil samples. Denitrification potential was highest in October and August. Although NO3 is definitely being removed from shallow groundwater, it is apparently not due to direct denitrification from the saturated zone. High denitrification potential in surface soils, especially near the field/forest interface, may contribute to NO3 disappearance from shallow groundwater. Processes associated with intact riparian vegetation appear to play the primary role in N removal.
Rates of Aluminum Dissolution in Acid Sandy Soils Observed in Column Experiments
Authors: van Grinsven Hans J.M. , van Riemsdijk Willem H. , Otjes René , van Breemen Nico
Published: July 2010

Soil weathering rates were estimated in small, packed soil columns in a controlled chemical environment. Cumulative leaching was described with a simple three‐parameter model, easing interpolation and extrapolation of experimental data. Dissolution of Al was the main buffering process in samples from two acid forest soils, viz. a Dystrochrept and Udipsamment. Aluminum‐leaching was associated with the presence of “free” Al‐oxides, which consist mainly of hydrated oxides of Al. The importance of dissolution of Al‐oxides was also indicated by the effect of temperature on the solubility and dissolution rate of Al. Dissolution rates of Al decreased exponentially with Al depletion from the soil sample (mol/kg) and on average increased with (H+)0.7. Depletion of reactive Al‐oxides in forest soils as a result of acid atmospheric deposition may be a future environmental problem.
Effects of Disturbance and Soil Amendments on Dissolved Organic Carbon and Organic Acidity in Red Pine Forest Floors
Authors: Cronan Christopher S. , Lakshman Sukla , Patterson Howard H.
Published: July 2010

A site manipulation experiment was conducted to test the effects of timing, drought, fertilization, sawdust amendment, and root trenching on water‐soluble humic substances in the O horizon of a mature red pine (Pinus resinosa Ait.) stand in Maine. Concentrations of water‐extractable dissolved organic carbon (DOC) in the sawdust and root trenching treatments were approximately twice as high as DOC in the untreated controls and other treatments. Mean carboxyl group contents of DOC ranged from 4.8 to 6.3 mol/kg C among treatments and controls. Control and drought treatments contained the highest carboxyl contents, whereas the sawdust and fertilizer treatments had the lowest carboxyl densities. Synchronous scan fluorescence spectra for the water extracts contained major peaks at 350, 395, and 470 nm, and these peaks were similar to those obtained for reference humic and fulvic acid standards, as well as selected aromatic model compounds. Overall, the fertilizer treatment produced a 20% decrease, the root trenching generated a 70% increase, and the sawdust treatment yielded a 120% increase in the release of organic acid ligands as compared with the control plots. The twofold range of variation in DOC and organic acidity associated with different substrate conditions in this experiment was considerably smaller than the tenfold range of variation reported in the literature for sites from diverse geographic locations. This suggests that the quantitative fluxes of DOC and organic acidity from forest soil O horizons are determined by the interactive effects of substrate conditions, climate, and other local site factors.
Effect of Tillage Systems and Rainfall Patterns on Atrazine Distribution in Soil
Authors: Sadeghi A. M. , Isensee A. R.
Published: July 2010

High variability of atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5 triazine) residues in soil and shallow groundwater have been reported under various agricultural management systems. This 2‐yr study was conducted to evaluate atrazine residue levels in soil as influenced by no‐till (NT) vs. conventional‐till (CT) under natural rainfall conditions. Atrazine was applied annually (at 1.34 kg/ha), 1 d after corn (Zea mays L.) planting, to two NT and two CT plots. Atrazine residues within the 0‐ to 10‐cm soil depth of CT plots were higher than in the NT plots, regardless of the difference in the rainfall patterns. Higher (ca. 61%) mean atrazine residues in the CT plots over NT plots in 1955 was most likely related to the rainfall that began 12 h after application. In contrast, in 1987, it rained 3 to 4 d after application and the residues in the CT were only 31% higher than in NT. These results indicate that even a subtle difference in rainfall distribution (temporal) can result in marked spatial variability in the distribution of atrazine.
Metal to Aluminum Correlation in Louisiana Coastal Wetlands: Identification of Elevated Metal Concentrations
Authors: Pardue J.H. , DeLaune R.D. , Patrick W.H.
Published: July 2010

Elevated toxic metal concentrations in Louisiana coastal wetlands are obscured by natural heterogeneity in baseline levels. Normalization of heavy metal concentrations to Al is a promising method for intersite comparison and for the identification of metal‐contaminated sites. We determined that Al significantly correlates with Pb (r2 = 0.88), Cd (r2 = 0.81), Cr (r2 = 0.45) in sediment samples from coastal Louisiana. These relationships were used to evaluate sites for metal contamination. Data from two potentially contaminated sites, Capitol Lake (Baton Rouge) and Bayou Trepagnier, fell well outside the prediction limits of the Al metal regression line for several of the metals. Samples from additional sites with no known metal contamination fell within the predictive limits of the regression equations. Metal: Aluminum regression relationships provide another tool for identifying areas of potential metal contamination in coastal wetlands but must be regionally correlated.
Soil Sorption of Volatile and Semivolatile Organic Compounds in a Mixture
Authors: Walton Barbara T. , Hendricks Marilyn S. , Anderson Todd A. , Griest W.H. , Merriweather R. , Beauchamp J.J. , Francis C.W.
Published: July 2010

Studies were conducted to evaluate lipophilicity as a predictor sorption for a mixture of organic compounds with high vapor pressures commonly present at hazardous waste sites. Sorption partition coefficients (Kp) for the mixture of 16 volatile and semivolatile organic compounds were measured on a Captina silt loam (Typic Fragiudult) and a McLaurin sandy loam (Typic Paleudults) using a zero headspace extractor. The experimental Kp was determined for acrylonitrile, furan, methyl ethyl ketone, tetrahydrofuran, benzene, toluene, p‐xylene, chlorobenzene, chloroform, nitrobenzene, 1,2‐dichlorobenzene, 1,2,3‐trichloropropane, carbon tetrachloride, ethylene dibromide, 1,2,4,5‐tetrachlorobenzene, and hexachlorobenzene on each of the two soils. The Kp values were generally lower in the McLaurin sandy loam, which had a lower organic C content (0.66 ± 0.04%) than the Captina silt loam (organic C content = 1.49 ± 0.06%). Sorption was normalized to soil organic C content of the soil by converting Kp for each compound and soil to Koc. Weighted regression analyses of Koc observed for the compounds in the mixture on Koc predicted from the n‐octanol/water partition coefficient (Kow) for individual compounds yielded a pooled, weighted regression of Koc observed = 1.084 + 0.457 Koc predicted, n = 29, r = 0.88. Statistical analysis indicated that the slope of 0.457 ± 0.046 (estimated standard error) was significantly less than 1.00, indicating that soil sorption of nonionic organic compounds differed from that predicted for the same individual compounds based on Kow. The results indicate that predictive equations for sorption of individual organic compounds can be applied to mixtures of volatile and semivolatile organic compounds in soils when log Kow are in a range from approximately 1 to 3; however, outside this range a correction factor may be needed.
Indicator Bacterial Survival in Stream Sediments
Authors: Sherer Brett M. , Miner J. Ronald , Moore James A. , Buckhouse John C.
Published: July 2010

The impact of grazing cattle (Bostauras) on water quality has been the subject of considerable interest as water quality standards become more restrictive. Benthic sediments have been found to harbor significantly higher concentrations of enteric bacteria than the overlying water. In this study, the survival of fecal coliform and fecal streptococci organisms was demonstrated to be significantly longer in sediment laden waters than in those without sediment and further the survival was longer in the sediment‐laden waters than in a supernatant from that same sediment suspended in water. Fecal coliform and fecal streptococci bacteria revealed half‐lives from 11 to 30 d and 9 to 17 d, respectively when incubated with sediment. This is longer than when they are similarly incubated without sediment.
Nitrate Levels in Shallow Groundwater under Pastures Receiving Ammonium Nitrate or Slow‐Release Nitrogen Fertilizer
Authors: Owens L.B. , Edwards W.M. , Van Keuren R.W.
Published: July 2010

This study examined the impact on groundwater quality of conventional and slow‐release N fertilizer to small, grazed watersheds in eastern Ohio. Three small watersheds (each less than 1 ha) received 56 kg N/ha annually as NH4NO3 for 5 yr. For the next 10 yr, one watershed received 168 kg N/ha annually as NH4NO3 and two others received the same amount of N as methylene urea, a slow‐release fertilizer. Shallow groundwater samples were collected from springs and analyzed. After the 5‐yr prestudy period, NO3‐N levels in the groundwater from the three watersheds were in a 3 to 5 mg/L range. Groundwater NO3‐N concentrations increased slightly during the first 3 yr at the higher N fertilizer rate, though they remained in the 3 to 5 mg/L range. Nitrate‐N levels increased more sharply during the rest of the study. Although these NO3‐N levels varied more between the growing and dormant seasons than when lower rates of fertilizer were applied, they eventually reached a slower rate of increase. During the 9th and 10th yr of the high application, seasonal NO3‐N levels in groundwater ranged from 10 to 16 and 7 to 14 mg/L from the watersheds receiving NH4NO3 and methylene urea, respectively. This study showed that 168 kg N/ha was too much for this system, regardless of whether conventional or slow‐release N was used.
Fractionation of Phosphorus in the Sediment of a Wetland after a Decade of Receiving Sewage Effluent
Authors: Cooke James G. , Stub Laila , Mora Neil
Published: July 2010

Sediment deposited in traps positioned along a pollution gradient in a wetland receiving sewage effluent was fractionated with respect to phosphorus (P) to understand the processes of P removal. Significant differences in P fractions were found between sites. Close to the point of effluent discharge, virtually all of the P deposited was in organic form; whereas downstream of a confluence with a wetland not impacted by the sewage, inorganic P constituted 50 to 80% of the total P. More than 80% of the inorganic P occurred in forms extractable by 0.1 M NaOH. This form of P was highly correlated (r2 ≃0.5–0.8) with oxalate‐extractable Fe. Natural wetlands unimpacted by sewage effluent were shown to be the main source of the Fe. Hydrologic conditions regulating the delivery of Fe to the sewage‐impacted wetland were implicated as the main factors determining the relative concentrations of inorganic P within the impacted wetland system. While it is not clear whether adsorption or precipitation reactions were responsible for the P deposition, we conclude that the present rate of P removal is sustainable. Our results may explain why, in some cases, the P removal achieved in wastewater wetland systems is much greater than can be predicted solely from soil adsorption maxima.
Redistribution of Sludge‐Borne Cadmium, Copper, and Zinc in a Cultivated Plot
Authors: Yingming Liang , Corey R.B.
Published: July 2010

The vertical and horizontal redistribution of sludge‐borne Cd, Cu, and Zn was studied in and around a 6.1 by 7.3 m plot on Plano silt loam (Typic Argiudoll) that had received 112 Mg−1 of sewage sludge in the fall of 1978. This plot had been moldboard‐plowed and disked each year thereafter. Calculated loadings of trace metals to the cropped plot from the sludge application were: Cd, 25.6 kg ha−1; Cu, 149 kg ha−1; and Zn, 538 kg ha−1. Two hundred surface soil samples (0–20 cm) were taken from areas within the plot and up to 3 m on each side of the plot and 39 subsoil samples (20–30, 30–40, and 40–60 cm) were taken within the plot in the spring of 1989. Estimates of total trace‐metal concentrations in the soil samples were obtained by determining metal concentrations in a 4 M HNO3 extract (70°C) by atomic absorption spectrometry. The determined distributions of sludge‐borne Cd, Cu, and Zn, respectively, were: 66.7, 67.5, and 68.0% in the 0‐ to 20‐cm plow layer within the original pot area; 15.5, 18.1, and 21.0% dragged outside the plot area; and 15.2, 12.4, and 11.6% moved into the 20 to 30‐cm layer within the plot area. No significant enrichment with trace metals from the sludge application was found below 30 cm. Of the metals found outside the boundaries of the original plot, about 56% moved into adjacent areas in the direction of tillage and about 44% into areas perpendicular to the direction of tillage. A mass balance calculation using an assumed soil bulk density of 1.3 Mg m−3 showed an average recovery of 98.7% of the added metals.
Laboratory Observation of Funnel Flow Mechanism and its Influence on Solute Transport
Authors: Kung K.‐J. S.
Published: July 2010

Recent field experiments have strongly indicated that contaminants could move preferentially and rapidly in unsaturated soils. Without knowing a priori what the preferential flow mechanisms are, it is impossible to predict solute movement based on numerical modeling with limited measured soil properties. The objective of this study was to characterize the mechanism of funnel flow (i.e., how an inclined soil layer with abrupt textural discontinuity will trigger preferential flow) in laboratory experiments and to determine the influence of funnel flow on solute transport. To simulate soil heterogeneity encountered in the field, a coarser sand lens with 15° inclination was packed in finer sand in a sand tank; three combinations of the coarser lens embedded in finer particles were tested. Water was applied at seven different rates in each combination to determine how the textural discontinuity between the two media would initiate the funnel flow, and to identify the critical water application rate at which water would enter the coarse sand lens. The water flow pattern, the influence of funnel flow on solute transport, and the effect of hysteresis on the funneling phenomenon were also examined. Results showed that funnel flow could occur along an inclined boundary between two soils if the following two conditions are both satisfied: (i) there is a macroscopic Haines' jump across the boundary, and (ii) water application rates are smaller than a certain critical rate. Under this condition, contaminants could be greatly congregated and accelerated by funnel flow.
The Effects of Establishment Methods and Fertilization Practices on Nitrate Leaching from Turfgrass
Authors: Geron C. A. , Danneberger T. K. , Traina S. J. , Logan T. J. , Street J. R.
Published: July 2010

A lysimeter study was conducted at the Ohio State University Turfgrass Research Center, Columbus, to investigate NO3‐N leaching losses from fertilized turfgrass. Nitrogen fertilizer treatments were applied to ‘Baron’ Kentucky bluegrass (Poa pratensis L.) seeded and sodded turf established on a Miamian silt loam (fine, mixed, mesic Typic Hapludalf). Treatments included two N sources, urea and resin‐coated urea (RCU); and Two fertilization programs, one that emphasize spring and summer applications (SSF) and the second program that included a late season application (LSF). Both the SSF‐ and LSF‐fertilization programs received 218.2 kg N ha−1 yr−1. The NO3‐N leachate concentrations from seeded turfgrass exceeded those from sodded turf for the first 3 mon. As the turf matured, NO3‐N losses from sod exceeded NO3‐N from the seeded plots. Leachate concentrations were 1.1 and 3.5 mg NO3‐N L−1 for seed and sod turf, respectively, from April 1990 through March 1991. Less rooting in the sodded plots resulted in greater N loss. Annual NO3‐N losses were not affected by N source. During the winter of 1991, significantly (P = 0.05) higher percolate NO3‐N concentrations were recorded from urea‐treated plots (3.66 mg NO3‐N L−1) vs. RCU (2.10 mg NO3‐N L−1), however. Similarly, N programs did not result in annual differences in percolate concentration, but differed during the winter of 1991. Concentrations were 3.37 and 2.39 mg NO3‐N L−1 for LSF and SSF, respectively. The NO3‐N leaching losses from all treatments exceeded the maximum concentration limit (MCL) early in the study. These high concentrations were caused by soil disturbance during establishment. During the 2nd yr, NO3‐N leaching results were more representative of typical turfgrass situations with mean annual flow‐weighted NO3‐N concentrations well below the MCL. Different N sources and fertilizer programs did not result in greater NO3‐N percolate losses compared to unfertilized turfgrass plots.
Biodegradation of Synthetic Chelates in Subsurface Sediments from the Southeast Coastal Plain
Authors: Bolton H. , Li S. W. , Workman D. J. , Girvin D. C.
Published: July 2010

The codisposal of synthetic chelating agents [e.g., ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (NTA)] and radionuclides has been implicated in increased radionuclide transport in the subsurface environment. Microbial transformations of chelates in the subsurface are currently unknown, but could influence chelate persistence and thus alter the transport of radionuclides. Surface soil and subsurface sediments from five formations (36‐ to 376‐m depth) were collected near Allendale, SC. Aerobic mineralization of 14C‐labeled EDTA, DTPA, and NTA occurred in select sediments indicating that subsurface microorganisms can degrade chelates, whereas chelates may be relatively stable in strata where limited mineralization occurred. The chelates were not mineralized more rapidly or to a greater extent in the surface soil than in the subsurface sediments. The relative order of chelate persistence was EDTA > DTPA > NTA, with the maximum amount mineralized during 115 d at 15, 26, and 43%, respectively. Maximum mineralization of all three chelates did not occur in the same sediment, indicating that different microbial populations were responsible for the degradation of each chelate. Mineralization of chelates was minimal under denitrifying conditions and was reduced when additional soluble C was added. There was no relationship between chelate mineralization and the adsorption of chelates to sediments or the aqueous speciation of the chelates.
Soil Nitrate Concentrations under Corn as Affected by Tillage, Manure, and Fertilizer Applications
Authors: Angle J. S. , Gross C. M. , Hill R. L. , McIntosh M. S.
Published: July 2010

A 3‐yr study was conducted to examine combination effects of tillage (no‐till, conventional‐till), manure, and inorganic fertilizer (ammonium nitrate) on leaching of nitrates from the root zone of corn (Zea mays L.). Soil cores were collected every spring to a depth of 210 cm and analyzed for NO3‐N. Leaching of NO3‐N significantly increased as fertilizer N rates increased, especially when rates exceeded the crop's potential to assimilate N. The concentration of soil nitrate (averaged over depth and tillage) in Year 3 of the study under the unfertilized control plots was 2.5 mg NO3‐N kg−1, whereas the concentration under plots fertilized with 260 kg N ha−1 was 8.7 mg NO3‐N kg−1. Soil nitrate concentrations were consistently lower under no‐tillage when compared with conventional‐tillage. Tillage differences were greatest when high rates of N were added to soil. These results indicate that the use of no‐tillage cultivation may reduce the leaching of nitrates beyond the crop root zone.
The Origin and Identification of Macropores in an Earthen‐Lined Dairy Manure Storage Basin
Authors: McCurdy M. , McSweeney K.
Published: July 2010

Earthen‐lined basins have been used to store dairy manure in Wisconsin since the early 1970s. Monitoring data indicate that many of these basins are leaking, but little effort has been directed toward explaining the mechanisms responsible for leakage. Morphological and micromorphological techniques were used to identify macropores in the sidewall of an earthen‐lined manure storage basin. Laboratory and field dye studies provided evidence of contaminant movement via macropores. Results indicate that physicochemical and biological mechanisms were responsible for creating macropores capable of providing pathways for preferential flow. These mechanisms, and the resulting macropores, can significantly affect the long‐term viability of earthen‐lined manure storage basins.
Changes in Mine Soil Properties Resulting from Overburden Weathering
Authors: Haering Kathryn C. , Daniels W. Lee , Roberts Jesse A.
Published: July 2010

Hard rock overburden is often used as a topsoil substitute for reclamation in the southern Appalachian surface mining region because of the limited availability of natural topsoil. In relatively unweathered overburden materials, soil‐forming processes are accelerated and the resulting mine soils form rapidly. Morphological, physical, and chemical properties related to overburden weathering in mine soils formed from siltstone and sandstone overburden were observed for 6 to 8 yr. Distinct surface soil horizons, enriched with organic matter, occurred within two growing seasons after mine soil construction, and discernible subsurface horizonation developed within four growing seasons. The degree of development of surface and subsurface soil horizons became more pronounced after 8 yr. Coarse fragment content of sandstone‐derived mine soils decreased, and silt content of siltstone‐containing mine soils increased during six growing seasons. Although pH and extractable Ca and Mg levels decreased during the first three growing seasons, apparently due to rapid leaching of exposed carbonates, these properties rebounded to near initial levels after six growing seasons due to release of Ca and Mg from continued carbonate weathering and phytocycling. Levels of extractable Fe tripled between the first and second growing seasons and then remained relatively constant for the rest of the study. The changes in soil properties in these mine soils indicated that geochemical weathering and oxidation was occurring rapidly. This study demonstrated the complexity of mine soil weathering and development processes and the difficulties involved in predicting all eventual mine soil properties from premining overburden analysis.
Compacted Soil Barriers at Abandoned Landfill Sites are Likely to Fail in the Long Term
Authors: Suter Glenn W. , Luxmoore Robert J. , Smith Ellen D.
Published: July 2010

At innumerable sites in the USA and around the world, buried waste has been isolated from the environment by barriers constructed entirely or in part of compacted soil. The chief concern in barrier design has been to isolate the waste in the short term by preventing movement of water into and through the waste. However, in the long term a variety of mechanisms can act to compromise this isolation. The mechanisms of long‐term failure include initial flaws in barrier construction, shrink‐swell cycles, freeze‐thaw cycles, erosion, subsidence, root intrusion, and animal intrusion. Evidence for action of all of these mechanisms is summarized. The likelihood of long‐term failure suggests that either perpetual care must be provided for buried hazardous wastes, or the waste sites must be designed to withstand long‐term threats to barrier integrity.
Environmental Impacts of Coal Combustion Residues
Authors: Carlson Claire L. , Adriano Domy C.
Published: July 2010

Coal combustion residues account for 90% of all fossil fuel combustion wastes produced in the USA. It is projected that by the year 2000 more than 150 million t of these materials will be produced in the USA each year. Presently, only about 20% of these wastes are utilized, with the remainder deposited in landfills or surface impoundments. This article reviews the information available concerning the environmental impacts associated with the disposal or utilization of coal combustion residues. The majority of the information available in the literature concerns the impacts of fly and bottom ashes; other coal combustion wastes have not received much attention. The major potential impacts of ash disposal on terrestrial ecosystems include: leaching of potentially toxic substances into soils and groundwater; reductions in plant establishment and growth due primarily to adverse chemical characteristics of the ash; changes in the elemental composition of vegetation growing on the ash; and increased mobility and accumulation of potentially toxic elements throughout the food chain. Ash disposal in landfills and settling ponds can influence adjacent aquatic ecosystems directly, through inputs of ash basin effluent and surface runoff, and indirectly, through seepage and groundwater contamination. Major impacts are generally associated with changes in water chemistry, including changes in pH and concentrations of potentially toxic elements. Using ash as a soil amendment can improve soil texture and water‐holding capacity, increase soil pH, and enhance soil fertility. However, it may also result in excessive soluble salt concentrations, excess B, and increased concentrations of other potentially toxic trace elements; reduction in the concentrations and/or availability of soil N and P; elemental imbalances due to excessively high pH; and cementation or compaction of soil. Scrubber sludge and fluidized bed combustion waste may be used as soil amendments as well, but also may create problems due to high alkalinity and high salinity.
Influence of Amount and Method of Irrigation Water Application on Leaching of Atrazine
Authors: Troiano J. , Garretson C. , Krauter C. , Brownell J. , Huston J.
Published: July 2010

A study was conducted to relate leaching of a herbicide, atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4,‐diamine], and inorganic water tracers, Br− and Cl−, to the amount of deep‐percolating water produced from irrigation. Soil at the site was classified as a Dehli Loamy Sand (Mixed, Thermic, Tepic Xeropsamment) which was an unstructured sandy soil that was low in organic C content, conditions conducive to solute leaching. The relationship between depth of solute movement and amount of deep‐percolating water was measured in sprinkler, basin, and furrow irrigation methods. Soil distribution of inorganic tracers indicated that graded levels of added water treatments, which were based on reference evapotranspiration, produced corresponding increases in the depth of percolated water. Atrazine's soil distribution indicated greater downward movement in response to increases in amount of deep‐percolating water. Magnitude of leaching differed between irrigation methods and increased in the order: sprinkler < basin < furrow. Simulations using the LEACHM model provided a physically based explanation for the differences in water movement between sprinkler and basin methods. The total amount of applied water was similar at each level of percolation but sprinkler irrigations were more frequent, resulting in more evaporation and, consequently, less water available for deep percolation. Both amount and method of water application are important factors that determine pesticide movement and that, in irrigated agriculture, must be considered as integral components of pesticide management.
Laboratory Experiments Evaluating the Transport and Fate of DBCP in Hanford Sandy Loam
Authors: Litton Gary M. , Guymon Gary L.
Published: July 2010

Soil column, batch adsorption, and batch biodegradatian experiments were conducted to determine the fate of DBCP applied in irrigation water at low concentrations (≈ 3 µg L−1) to unsaturated Hanford sandy loam soil (coarse‐loamy, mixed, nonacid, thermic Typic Xerorthents). The objective was to determine the extent that soil might treat DBCP‐contaminated groundwater proposed for irrigation of citrus in the Redlands California area. Water applications were performed cyclically to simulate citrus irrigation practices. Volatilization of DBCP to the atmosphere between irrigations was the dominant mechanism controlling its fate once applied to the soil. Soil adsorption was found to retard the transport of DBCP 3 to 5 times when compared with the wetting front movement. Batch biodegradation experiments suggested that DBCP may also be significantly metabolized by subsurface microorganisms. The half‐life was estimated to be approximately 7 d. Soil water characteristic curve hysteresis was observed with the soil column experiments and water content distributions calculated from soil water pore pressures required that scanning curves be developed to accurately simulate experimental data.
A Solid‐Phase Extraction Based Soil Extraction Method for Pesticides of Varying Polarity
Authors: Turin H. J. , Bowman R. S.
Published: July 2010

Solid‐phase extraction (SPE) is an innovative method for efficiently and quantitatively extracting pesticides from large numbers of soil samples. An extraction method using commercially available SPE columns has been developed and tested using three herbicides of varying polarity: bromacil [5‐bromo‐6‐methyl‐3‐(1‐methylpropyl)‐2,4(1H,3H)pyrimidinedione], napropamide [N,N‐diethyl‐2‐(1‐naphthalenyloxy)propanamide], and prometryn [N,N′‐bis(1‐methylethyl)‐6‐(methylthio)‐1,3,5‐triazine‐2,4‐diamine]. The soil sample is shaken with a methanol/water mixture and centrifuged. The supernatant is then diluted with a concentrated NaCl solution, and drawn through an SPE column. The sorbed pesticides are finally eluted from the column with methanol. This method requires no specialized laboratory equipment and is well suited for processing large numbers of samples. Analyses of spiked soil samples show recoveries of over 90% and average coefficients of variation (CV's) ranging from 5% at high soil pesticide concentrations to 18% at lower concentrations. The practical detection limit for the method is approximately 10 µg/kg.
Agricultural Water Quality Priorities: A Symposium Overview
Authors: Gish Timothy J. , Sadeghi Ali
Published: July 2010

To meet the global needs of a growing population, both increased productivity and additional land may need to be dedicated to agriculture. However, to effectively evaluate the impact of new farming strategies and agricultural chemicals on the environment, a broad perspective is needed to prevent simply shifting pollution from one part of the hydrologic cycle to another. The loss of agricultural chemicals to the environment may include a combination of processes such as volatilization, runoff and leaching, each exhibiting considerable spatial and temporal dependency. Subsequent losses of agricultural chemicals to the environment may also be transported offsite, having a potential detrimental effect on the environment. This overview provides a brief introduction to the papers presented at a special USDA‐ARS symposium entitled “Agricultural Water Quality Priorities, A Team Approach to Conserving Natural Resources.”
Occurrence of Nitrate in Groundwater—A Review
Authors: Spalding R. F. , Exner M. E.
Published: July 2010

The results of federal, state, and local surveys, which included more than 200 000 NO3‐N data points, are summarized in this review of NO3 in groundwater in the USA. The levels of NO3‐N are associated with source availability and regional environmental factors. In regions where well‐drained soils are dominated by irrigated cropland, there is a strong propensity toward the development of large areas with groundwater that exceeds the maximum contaminant level of 10 mg/L NO3‐N. Most of these areas are west of the Missouri River where irrigation is a necessity. Aquifers in highly agricultural areas in the southeastern USA reportedly are not contaminated. Vegetative uptake and denitrification in this warm, wet, C‐rich environment are responsible for the natural remediation of NO3 in shallow aquifers. In the Middle Atlantic states and the Delmarva Peninsula, localized contamination occurs beneath cropped, well‐drained soils that receive excessive applications of manure and commercial fertilizer. Extensive tile drainage has for the most part prevented a NO3 problem in the groundwater of the Corn Belt states. Throughout the USA there are recurring themes. They include a decrease in NO3‐N levels with depth; lower NO3‐N levels in shallow wells (< 8 m); and a significant increase in NO3‐N in older wells and in wells with poor construction. The factors affecting the distribution of NO3 in aquifers are complex and poorly understood. Interdisciplinary studies using discrete depth sampling, hydrogeological indicators, isotopic tracers, and microbiological techniques are necessary to unravel the complex dynamics.
RUSLE Model Description and Database Sensitivity
Authors: Renard K. G. , Ferreira V. A.
Published: July 2010

Water quality modeling generally requires estimates of the amount of eroded material entering water courses. This information is necessary because sediment often transports adsorbed chemicals. Numerous models have been developed to assist with assessment of this problem. These models often contain some modification of the Universal Soil Loss Equation (USLE). A recently initiated effort to improve USLE technology has produced a computer‐based model, RUSLE (Revised USLE), which employs new relationships to estimate values of the six factors in the equation. Three input databases are required: climatic data, crop data, and field operations data. Although numerous specific entries for these data are contained in the program, in many cases users must supplement or modify the supplied data. Results of a sensitivity analysis help users tailoring the databases to specific conditions.