bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Determination of Arsenite, Arsenate, Selenite, and Selenate by Suppressed Ion Chromatography
Authors: McGeehan S.L. , Naylor D.V. 
Published: July 2010

AbstractStudies of chemical processes involving As and Se in soil solution require accurate determination of arsenite, arsenate, selenite, and selenate. Many of the currently used speciation techniques rely on indirect measurement of one or more species. Direct, simultaneous measurement of these As and Se ionic species was achieved using a commercially available suppressed ion chromatography system and a Na2CO3‐NaHCO3 eluant. Electrochemical and conductivity detectors were used in series with a dual‐channel integrator to quantify arsenite, arsenate, selenite, and selenate. Resolution of the As and Se ionic species from the other ions depended on the nature of the eluant. An eluant containing 2 mM Na2CO3 and 1.7 mM NaHCO3 provided a good compromise between analyte resolution and time of analysis. Concentrations of 1 mg L−1 each of arsenite, arsenate, selenite, and selenate were measured in the presence of 50 mg L−1 each of F, Cl, NO3‐N, SO4‐S, and PO4‐P. Detection limits ranged from 0.016 mg L−1 for selenite to 0.120 mg L−1 for arsenate. The detection limits for arsenate and selenite obtained using this suppressed ion chromatographic technique were lower than values reported in the literature using nonsuppressed ion chromatography. Precision of analysis decreased with decreasing analyte concentration. The ion chromatographic method was compared to spectroscopic methods using analyses of soil solution, receiving As and Se spikes, and analyses of adsorption equilibrium solutions. The results of this study show that suppressed ion chromatography is a reliable method for determination of the As and Se oxyanions in soil solution.
Remediation of Solvent‐Contaminated Soils by Aeration
Authors: Kempton Houston , Davis Andy , Olsen Roger 
Published: July 2010

AbstractA bench‐scale box test was performed to evaluate the feasibility of rototilling to remediate excavated soils contaminated with tetrachloroethylene (PCE), trichloroethylene (TCE), and 1,1,1‐trichlorocthane (1,1,1‐TCA). Two clay‐rich soils (A and B) containing 0.15% organic C and different concentrations of the target analytes were placed in 15‐cm thick layers under a 10 km h−1 wind, tilled daily, and samples collected and analyzed periodically. Soil A (25 000 µg kg−1 PCE) lost 80% after 24 h and 97% after 407 h. Soil B (8881 µg kg−1 PCE) lost 29% after 24 h and 92% after 407 h. Initial TCE and 1,1,1‐TCA concentrations ranged from 793 to 1570 µg kg−1. Relative volatilization loss rates were similar to that of PCE. The average volatilization half‐lives of the solvents were 1.2 d for PCE, 0.58 d for TCE, and 0.64 d for 1,1,1‐TCA. Removal of the analytes slowed considerably after 200 h, with a small (up to 10%) amount of each analyte retained in refractory sites. Residual solvent concentrations in soils A and B after 407 h were 835 and 719 µg kg−1 PCE, 38 and 95 µg kg−1 TCE, and 21 and 31 µg kg−1 1,1,1‐TCA. Simulations of volatilization using the pesticide root zone model (PRZM) accurately predicted the loss of PCE, TCE, and 1,1,1‐TCA over the first 24 h when most of the solvent volatilized, but the model over predicted contaminat losses at longer durations when remnant soil concentrations were less than six times the concentration bound to refractory sites.
Lead Levels in Blood from Cattle Residing near a Lead Smelter
Authors: Neuman D.R. , Dollhopf D.J. 
Published: July 2010

AbstractConcentrations 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

AbstractThis 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

AbstractThe 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

AbstractThe 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

AbstractComposting 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

AbstractA 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

AbstractStarch 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

AbstractOrganic 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

AbstractMechanisms 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

AbstractSoil 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

AbstractA 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

AbstractHigh 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

AbstractElevated 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.