bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vegetative Uptake of Technetium‐99 from Buried, Solidified, Low‐Level Radioactive Waste
Authors: Murphy Charles E. , Johnson Trudy L. 
Published: July 2010

AbstractAt the Savannah River Site, it is planned to dispose of liquid, lowlevel nuclear waste by incorporating the waste into a solid, concrete waste form called saltstone. Saltstone monoliths will be buried in claycapped, subterranean vaults. Although the vault/cap burial system is designed to severely limit the access of vegetative roots to the saltstone, a study was begun in 1984 to determine the potential for root uptake of radionuclides, in case an unforeseen accident should cause exposure of the buried saltstone. Thirty‐two lysimeters were designed, constructed, and filled with soil. Saltstone samples, containing the liquid, low‐level supernate from a waste disposal demonstration program, were buried in some of the lysimeters. The blocks were placed at varying depths to investigate the relationship between source depth and plant uptake. Other lysimeters, not containing saltstone, were used as controls. Crops, grass, and trees were planted in the lysimeters and sampled periodically to determine radionuclide concentrations. Water samples also were collected from the lysimeter sumps and analyzed for radionuclide content. In the 5 yr following establishment of the lysimeters, only technetium‐99 (Tc‐99) and cesium‐137 (Cs‐137) could be detected at elevated concentrations in the vegetation. The Cs‐137 concentration difference between the plants grown in control and saltstone lysimeters was so small that the difference was only barely detectible against background. The Tc‐99 concentration was significantly higher in the vegetation and the sump water of the lysimeters containing saltstone, when compared to the control lysimeters. The Tc‐99 uptake by the vegetation appears to be related to release of the Tc‐99 from the saltstone into the soil water. The Tc‐99 concentration in vegetation and sump waters shows a similar pattern, including an initial period of very low concentrations followed by a coincident build‐up period and a period of relatively uniform concentration. Vegetative uptake factors were calculated for uptake of Tc‐99 from soil water. The results were very similar for the vegetative parts of all the species grown, 111 to 376 (nBq/kgvegetation)/(nBq/kgwater). The uptake factor calculated for the seeds of crops was less by a factor of 100 than the uptake factor for vegetative parts.
A Greenhouse System for Determining Pesticide Movement from Golf Course Greens
Authors: Smith A. E. , Weldon O. , Slaughter W. , Peeler H. , Mantripragada N. 
Published: July 2010

AbstractThere is an increasing concern for the potential movement of chemicals from the treated sites following the use of certain management strategies for turfgrass maintenance. In some areas, these concerns are being translated into proposed government regulations for turfgrass management that could reduce amounts of chemicals available for the management strategies. The objective of this study was to develop a lysimeter system with a controlled environment for measuring the potential movement of pesticides through golf course greens designed to simulate United States Golf Association specifications. A track irrigation system was mounted above 36 lysimeters to simulate irrigation and rainfall common to the golf courses in the Piedmont region of Georgia. The system was tested for a 52‐wk period using ‘Tifdwarf’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy]. An excellent turfgrass sod was maintained during the trial period. The coefficient of variation (CV) in water delivery within the growth boxes was 5.6% and the average Cv of water delivery between the 36 growth boxes was 6.2%. The two rows of lysimeters contained either a 80:20 or 85:15 (sand/sphagnum peat moss) mixture. The average Cv for differences in volume of effluent exiting the lysimeter bases was 22%. Data for determining the potential movement of applied chemicals from golf course greens can be obtained from this system.
A Mimicked In‐Situ Remediation Study of Metal‐Contaminated Soils with Emphasis on Cadmium and Lead
Authors: Mench Michel J. , Didier Valérie L. , Löffler Monika , Gomez Alain , Masson Pierre 
Published: July 2010

AbstractThe capacity of several additives, i.e., lime, Thomas phosphate basic slag (TBS), hydrous iron oxides (HFO), hydrous manganese oxides (HMO), and Beringite, added to soil to fix Cd or Pb, was evaluated using two pot experiments in tandem with soil extractions. Three soils from France with metal contents ranging from 0.17 to 108 mg Cd kg−1 soil dry weight (DW) and 47 to 1112 mg Pb kg−1 soil DW were studied. Metal sources were: sludge‐borne metals (Soil A), fallout from a smelter (Soil B), and emission from a tetraethyl Pb production facility (Soil C). Ryegrass (Lolium spp.) or tobacco (Nicotiana tabacum L.) shoots were harvested. The addition of HMO decreased to a maximum extent Cd in ryegrass and tobacco for Soils A and B, but did not suppress the differences in Cd uptake between the two plant species. Use of HMO reduced Pb concentrations only in ryegrass shoots. Thomas phosphate basic slag lowered Pb bioavailability in Soils B and C. The addition of HMO into Soils A and B reduced Cd concentrations in water, 0.1 M Ca(NO3)2, or 0.43 M acetic acid (HOAc) extracts, but not in 0.05 M EDTA pH 7 extracts. Water and sequential extractions were employed on Soil C: HMO caused the most reduction in Pb water‐soluble and HOAc‐extractable fractions, and rendered Pb less extractable with H2O2 and more with HONH3Cl. The decrease of Cd‐ and Pb‐soluble fractions was reflected in their suppressed bioavailability. Among the screened additives, HMO exhibited a most promising potential to reduce either Cd or Pb transfer from soil to soil solution or their entry into the food chain via plant uptake. This material would be promising for in‐situ remediation technologies geared to restore Cd‐ and Pb‐contaminated soils. However, little is known about the kinetics and persistence of this chemical under field conditions.
Role of Genotype in the Response of Loblolly Pine to Tropospheric Ozone: Effects at the Whole‐Tree, Stand, and Regional Level
Authors: Taylor George E. 
Published: July 2010

AbstractThe interaction between tropospheric ozone (O3) and genotype in loblolly pine (Pinus taeda L.) is explored, focusing on the consequences of different genotypes in a range of basic and applied issues. General conclusions for loblolly pine are: (i) a genetic component underlying phenotypic variation in ozone response is documented at the biochemical, physiological, and whole‐plant level; (ii) ozone resistance determined from needle injury is not associated with resistance determined from growth or gas exchange; (iii) mode of inheritance of resistance based on growth is not documented, although evidences point to a multilocus model; (iv) resistance involves avoidance and tolerance mechanisms, and evidence for pleiotropy indicates that resistance carries costs that are important in terms of physiologic ecology and breeding strategies; and (v) breadth of genetically determined variation has consequences for experimental designs, ecological risk assessment, genetic diversity and air quality standards. The threshold for growth effects on average seedlings approaches a 12‐h mean concentration of 45 nL L−1, which is below extant air quality in many Southeastern forests. The threshold for sensitive cohorts approaches 25 nL L−1, near the projected concentration a century ago (19 nL L−1). Extant ozone levels are affecting the average loblolly pine intermittently and sensitive cohorts frequently or continuously. The responsiveness of sensitive cohorts is important in understanding how regional stresses will impact ecological resources. Air pollution research in the last decade emphasized the development of exposure‐response relationships, centering on selection of statistical indicators of atmospheric ozone. The conclusion that genetic variation is a major source of variation indicates that further improvement in exposure‐response relationships will emerge from efforts addressing variability driven by biospheric rather than atmospheric processes.
Hexavalent Chromium Solubility and Reduction in Alkaline Soils Enriched with Chromite Ore Processing Residue
Authors: James Bruce R. 
Published: July 2010

AbstractHealth‐based regulatory limits and remediation strategies for chromate [Cr(VI)] in alkaline soils enriched with chromite ore processing residue (COPR) should be based on oxidation‐reduction and solubility interactions of Cr. A laboratory study characterized the solubility of Cr(VI) by sequential batch equilibrations and teachings from two COPR‐enriched soils using dilute salt and acid solutions. Batch equilibrations quantified reduction of soluble and insoluble Cr(VI) in the whole soils and extracted solutions. The soils, termed Low Hex and High Hex, contained 105 and 460 mg Cr(VI) kg−1, 1.8 and 10.4 g total Cr kg−1, and had pH values of 8.5 and 10.4, respectively. Total cumulative Cr(VI) removed by the extractions was 49 and 386 mg kg−1 by both the batch equilibrations and leaching methods in the Low and High Hex soils, respectively, and no differences were found among the extractants. Addition of Mn2+ resulted in 50 to 100% reduction of soluble Cr(VI) in both soils without pH adjustment, a new finding that is thermodynamically predictable at pH > 7.2, and it is in sharp contrast to the ability of Mn(III,IV) oxides to oxidize Cr(III) to Cr(VI) in more acidic soils and Mn oxide suspensions. Additions of Fe2+, steel wool (Fe), leaf litter, and lactic acid (a component of human sweat) also reduced various quantities of soluble and insoluble Cr(VI) in the soils, depending on pH, reducing agent, and soil. Soluble Cr(VI) in these COPR‐enriched soils appeared to be controlled by dissolution of a moderately soluble chromate salt, such as CaCrO4, and not by sorption or oxidation‐reduction equilibria.
Considerations for Evaluating Controlled Exposure Studies of Tree Seedlings
Authors: Peterson Charles E. , Mickler Robert A. 
Published: July 2010

AbstractTree seedling exposure studies, covering a wide range of experimental conditions in pollutant treatments, species, facilities, and exposure regimes, have been conducted during the past several years to determine acute effects and relative sensitivity of tree species in response to simulated acid precipitation and gaseous pollutants. Because of the difficulties inherent in conducting controlled exposures with mature trees (e.g., size, variability among experimental units, and costs associated with replication of treatments), seedling exposure studies have been initiated as the quickest way to address these issues. However, sufficient consideration has not been given to either the comparability of seedling studies or to their appropriate inference. The statistical power of any given analysis is rarely discussed when the outcomes are published. Appropriate and documented statistics of experimenter bias are often not reported, and variability in the exposure regime (i.e., treatment target levels) and the measurement of experimental variables is assumed to be zero, rather than quantified. Finally, the populations of seedlings for which seedling experiments have inference, the extent to which seedling responses are applicable to mature trees and forest condition, and the limitations in national or regional generalizations are crucial issues often left to an individual reader's interpretation without the benefit of adequate quantitative information presented by the authors.
Nitrate Leaching from Nitrogen‐Fertilized and Manured Corn Measured with Zero‐Tension Pan Lysimeters
Authors: Jemison John M. , Fox Richard H. 
Published: July 2010

AbstractExcessive N fertilization increases the potential for nitrate (NO−3) leaching, but no research has evaluated NO−3 leaching from corn (Zea mays L.) receiving economic optimum N rates (EON). This study assessed (i) flow‐weighted average concentration and mass of nitrate‐N (NO3‐N) leached from nonmanured and manured corn treated with five fertilizer N levels and at EON, and (ii) the relationship between NO3‐N mass in the 1.2‐m soil profile following harvest and the flow‐weighted average leachate concentrations. Following application of liquid dairy manure each April, the field was chiseled and disked prior to planting. Ammonium nitrate was broadcast at planting (0–200 kg N ha−1 in 50‐kg increments and 0–100 kg N ha−1 in 25‐kg increments) in the nonmanured and manured corn. Eighteen (0.465 m2) pan lysimeters were placed 1.2 m below the soil surface in zero, intermediate, and high N treatments. Zero‐N plots had 3‐yr average flow‐weighted leachate concentrations less than 10 mg NO3‐N L−1. At EON, the 3‐yr averages were 18.8 and 19.3 mg NO3‐N L−1 for nonmanured and manured corn. Nitrogen rate influenced mass of NO3‐N leached only when collection efficiency estimates were used to account for pan bypass flow. In the nonmanured corn, the 3‐yr average amount of NO3‐N leached was 107 kg ha−1 or 36% of the N applied at EON. Total mass of NO3‐N in the 1.2‐m soil profile following harvest was useful to predict annual flow‐weighted average leachate NO3‐N concentrations, but this is not practical in most soils of the Northeast.
Denitrification Loss from Two Pennsylvania Floodplain Soils
Authors: Schnabel R. R. , Stout W. L. 
Published: July 2010

AbstractDenitrification losses and dissolved nitrous oxide concentration within a well‐ and poorly‐drained soil under ryegrass (Lolium perenne L.) were measured for ≈12 mo. The soils received up to 252 kg N/ha as potassium nitrate in two equal amounts. Denitrification increased in March as the soil warmed to 5 to 7 °C with the highest rates occurring soon after N was applied. Approximately 30% of annual loss occurred within 2 wk of fertilization. Dissolved nitrous oxide concentration peaks corresponded to periods with elevated denitrification. On average, the poorly‐drained soil denitrified the equivalent of 40% of applied N (up to 110 kg N/ha). Less than 2.5 kg/ha was denitrified from the well‐drained soil. The degree of anoxia in the measurement apparatus substantially effected measured denitrification rates. Consequently, it is important to know the relationship between redox in‐situ and in the measurement apparatus.
Phosphorus Retention by Wetland Soils used for Treated Wastewater Disposal
Authors: Gale P. M. , Reddy K. R. , Graetz D. A. 
Published: July 2010

AbstractWetlands function as buffers for nutrients loaded from terrestrial ecosystems through drainage and surface discharges. The objectives of our study were to (i) determine the P retention capacity of representative wetland soils being used for disposal of treated wastewater and (ii) relate P retention characteristics to selected physicochemical properties to evaluate likely mechanisms of P removal in the soils. Intact soil cores (0–40 cm) and bulk soil samples (0–15 cm) were collected from a system of natural and constructed wetlands currently being used for disposal of treated wastewater. Floodwater P concentrations of the intact soil cores were monitored over time to determine the rate of P removal. Batch experiments were conducted to determine maximum P retention capacity of the soils. Soil samples were analyzed for inorganic P pool sizes, and selected physicochemical properties. During a 21 d hydraulic retention time, the constructed wetlands (sandy, low organic matter soils) retained 52 to 66% of added P, as compared with 46 to 47% retained by the natural wetlands (high organic matter soils). The P retention maximum, as estimated using the Langmuir model, ranged from 196 to 1821 mg P kg−1 (aerobic incubations) and from 32 to 1415 mg P kg−1 (anaerobic incubations). The P sorption maximum for these soils could be predicted by batch equilibration with a single high P solution. Anaerobic conditions increased P solubility. Organic P pools and the Fe‐Al‐bound fraction seemed to control P chemistry in these natural and constructed wetlands.
An Improved Zero‐Tension Lysimeter to Monitor Colloid Transport in Soils
Authors: Thompson Michael L. , Scharf Richard L. 
Published: July 2010

AbstractMobile colloids may facilitate the long‐distance transport of actinides, organic contaminants, and heavy metals in soil, surface water, and groundwater. Detection of colloid‐facilitated contaminant transport in soils requires adequate monitoring before, during, and after in‐situ remediation treatments. Zero‐tension lysimeters (ZTLs) are devices designed to collect water that moves through the soil under the influence of gravity; they can also be used to collect mobile colloids. A ZTL that is suitable for monitoring colloid‐facilitated contaminant migration consists of a specially designed collection cup placed below an undisturbed core of soil that has been initially withdrawn with a hydraulically powered tube. Field tests of the lysimeter were conducted at a site near Ames, IA, where three levels of municipal sewage sludge were applied to the soil in 1992. Each ZTL required about 45 min for a two‐person crew to install at 50‐cm depth. Turbidity measurements of leachate following summer storms revealed considerable spatial variability in colloid migration, supporting the use of ZTLs that can be installed quickly and cheaply in large numbers at a study site. The ZTL described has significant advantages over conventional designs with respect to simplicity and speed of installation. Therefore, it allows colloid transport to be monitored at more locations at a given site. In addition, because of the improved spatial resolution in sampling and monitoring, if contaminants are mobilized, their source can be more easily identified than with piezometer‐based monitoring methods.
Response of Plants to Interacting Stresses (ROPIS): Program Rationale, Design, and Implications
Authors: Goldstein Robert , Ferson Scott 
Published: July 2010

AbstractThe Response of Plants to Interacting Stresses (ROPIS) program was designed to provide a mechanistic framework for analysis and prediction of the effects of air pollution (i.e., tropospheric ozone, acidic precipitation) and other environmental stresses on plants. Focusing on regionally important tree species, the program used experimental studies in the field and laboratory in combination with modeling efforts to evaluate how stresses affect material flow and transformation within the plant and material flow across the plant's boundaries with the soil and the atmosphere. Based on the wealth of results from the program, the stresses directly or indirectly altered flows and transformations that control a plant's carbon, nutrient, and water balances; in turn, these stress‐induced effects altered material uptake, biomass production, partitioning of dry matter at the whole‐plant level, and the plant's ability to compete for limited resources in the environment. It is proposed that process‐level models of material flow within a plant and between a plant and the surrounding environment can be used to integrate and predict plant response to interacting stresses of natural and anthropogenic origin.
Integrating the Effects of Simultaneous Multiple Stresses on Plants Using the Simulation Model TREGRO
Authors: Weinstein David A. , Yanai Ruth D. 
Published: July 2010

AbstractTREGRO, a model of tree physiological response to environmental stress, was developed to examine the details of tree response to the interaction between ozone stress and nutrient deficiency. TREGRO was used to test the hypothesis that the nutrient deficiency would exacerbate growth reductions caused by ozone. When TREGRO was applied to a range of multiple‐stress scenarios involving these two stresses, the simulated effects of the combined stresses in reducing red spruce (Picea rubens Sarg.) tree growth were less than the sum of the effects simulated when each stress was acting alone. Red spruce, a species with a growth strategy involving low maximum potential growth rates and storage in C reserves, showed simulated patterns of allocation that minimized the added effect of ozone when Mg nutrient availability was low. In contrast, ponderosa pine (Pinus ponderosa Dougl.), a species that allocated C to the construction of new tissue preferentially, showed little ability to ameliorate ozone stress under low nutrient conditions. In neither case were the effects of ozone increased by nutrient deficiency. It is speculated that a species which maintains maximum C demand rates considerably below rates of C supply may be better able to adjust to conditions of multiple stresses.
Managing Agricultural Phosphorus for Protection of Surface Waters: Issues and Options
Authors: Sharpley Andrew N. , Chapra S. C. , Wedepohl R. , Sims J. T. , Daniel T. C. , Reddy K. R. 
Published: July 2010

AbstractThe accelerated eutrophication of most freshwaters is limited by P inputs. Nonpoint sources of P in agricultural runoff now contribute a greater portion of freshwater inputs, due to easier identification and recent control of point sources. Although P management is an integral part of profitable agrisystems, continued inputs of fertilizer and manure P in excess of crop requirements have led to a build‐up of soil P levels, which are of environmental rather than agronomic concern, particularly in areas of intensive crop and livestock production. Thus, the main issues facing the establishment of economically and environmentally sound P management systems are the identification of soil P levels that are of environmental concern; targeting specific controls for different water quality objectives within watersheds; and balancing economic with environmental values. In developing effective options, we have brought together agricultural and limnological expertise to prioritize watershed management practices and remedial strategies to mitigate nonpoint‐source impacts of agricultural P. Options include runoff and erosion control and P‐source management, based on eutrophic rather than agronomic considerations. Current soil test P methods may screen soils on which the aquatic bioavailability of P should be estimated. Landowner options to more efficiently utilize manure P include basing application rates on soil vulnerability to P loss in runoff, manure analysis, and programs encouraging manure movement to a greater hectareage. Targeting source areas may be achieved by use of indices to rank soil vulnerability to P loss in runoff and lake sensitivity to P inputs.
Nitric and Nitrous Oxide Emissions and Soil Nitrate Distribution in a Center‐Pivot‐Irrigated Cornfield
Authors: Guenzi W. D. , Hutchinson G. L. , Beard W. E. 
Published: July 2010

AbstractResearch on soil N loss mechanisms remains a high priority not only because of the need to increase agricultural N use efficiency, but also because of environmental concernsuch as NO−3 contamination of groundwater and increasing N oxide concentrations in the atmosphere. We measured NO and N2O emissions and downward movement of NO−3 in an eastern Colorado corn (Zea mays L.) field irrigated with a modified center‐pivot system that applied water to alternate furrows. One hour after infiltration of the irrigation water, emission rates measured by an enclosure method ranged from 0 to 6 g N ha−1 d−1 for NO and 0 to 26 g N ha−1 d−1 for N2O. The emission rates were largest after the first irrigation and much smaller following subsequent irrigations. Greater N oxide evolution from nonirrigated furrows than adjacent irrigated furrows probably resulted from lateral transport of gases produced in the wet soil. Analyses of soil cores taken after planting and after harvest provided no evidence that NO−3 moved below the root zone during the growing season, despite the presence of substantially more inorganic N than required for maximum corn yield. These data suggest that when the size and frequency of irrigations are efficiently managed, use of a low energy precision application (LEPA) irrigation system results in no N loss to groundwater and no economically significant gaseous N oxide loss to the atmosphere.