bluuebunny/crossref_metadata_2025 huggingface dataset:
Tebuthiuron Persistence and Distribution in Some Semiarid Soils
Authors: Johnsen Thomas N. , Morton Howard L.
Published: July 2010

Tebuthiuron (N[5‐(1,1‐dimethylethyl)‐1,3,4‐thiadiazol‐2‐yl]‐N,N'‐dimethylurea) is a soil‐applied herbicide used on rangelands to control weeds and brush. This study was conducted at five previously treated semiarid rangeland locations in northcentral Arizona to determine how long tebuthiuron remains in the soil and to what depths it penetrates into the soil. Treatments were made from 1975 through 1979. Soils were collected from 1980 through 1986 at 0‐ to 7‐cm, 7‐to 15‐cm, and successive 15‐cm layers to bedrock or into caliche layers from the perimeter of 3‐ by 0.5‐m trenches dug perpendicular to the long axis of the plots. Tebuthiuron was assayed using gas chromatography with flame photometric detection. Tebuthiuron was detected in soil 11 yr after application. Most of the tebuthiuron detected was in the surface 30 cm of soil during the first 5 yr, but small amounts were detected as deep as 105 cm 6 and 9 yr after treatment. After 9 yr from 55 to 73% of the tebuthiuron detected was at the depth of between 60 and 90 cm.
Vegetative Filter Treatment of Dairy Milkhouse Wastewater
Authors: Schwer C. B. , Clausen J. C.
Published: July 2010

A vegetated filter strip constructed to treat milkhouse wastewater from a Vermont dairy farm was evaluated to determine its effectiveness in reducing solids, P and N concentrations and exports in surface and subsurface flow. The liquid waste was applied twice daily via a level lip spreader at a rate of 2.94 cm/wk on a vegetated loam soil having a 2% slope. The flow and concentrations of inputs and surface and subsurface outputs were continuously monitored during the 2‐yr study. The strip significantly (P < 0.01) reduced solids, P, and N on a concentration basis, and retained 95% solids, 89% P, and 92% N on a mass basis. Retention was the greatest during the growing season and the poorest during snowmelt periods. Concentrations in subsurface outputs were greater than in surface runoff and over 75% of the mass export was in subsurface flow. Comparisons of this study with values reported in the literature suggests that hydraulic loading rate governs the effectiveness of filter strip treatment.
Infiltration of Wastewater in a Newly Started Pilot Sand‐Filter System: II. Development and Distribution of the Bacterial Populations
Authors: Pell Mikael , Nyberg Fred
Published: July 2010

The objective of the study was to monitor the development of the bacterial populations in a sand‐filter system consisting of a three‐chambered septic tank, a sand filter with a one‐person capacity, and eight columns. The system was loaded with 67 L m−2 day−1 of an artificial wastewater. Monitoring was conducted from start‐up until a steady state was reached. The wastewater contained over two orders of magnitude higher numbers of aerobic bacteria in the third chamber compared to the first chamber of the septic tank. Populations of aerobic and denitrifying bacteria in the sand surface layer of the columns increased markedly in number within the first 10 d, reaching peaks on Day 24. The following decline was attributed to the development of anaerobic conditions. This hypothesis was supported by an observed increase in the number of sulfate‐reducing bacteria. No increase in nitrifier populations was observed. In the sand‐filter surface layer both aerobic and denitrifying bacteria increased in numbers until Days 65 to 75, thereafter remaining in a steady state at around 108 bacteria g−1 dry sand. Populations of ammonium‐ and nitrite‐oxidizing bacteria both started out at low levels. Thereafter they increased until Days 70 to 95, by which time populations of 106 to 107 and 105 to 106 g−1 dry sand, respectively, had been established. By the time that bacterial growth had reached a steady state, an estimated 8% of the pore volume in the sand surface layer was occupied by bacterial cells. This biomass accounts for the amounts of N and P in the sewage water produced by one person during a 20‐d period.
Dissolved Organic Matter Interaction with Napropamide and Four Other Nonionic Pesticides
Authors: Lee Dar‐Yuan , Farmer Walter J.
Published: July 2010

Equilibrium dialysis was used to measure the extent of interaction between dissolved organic matter (DOM) and five nonionic pesticides. The association‐dissociation of DOM with the relatively polar, nonionic pesticide napropamide [2‐(a‐naphthoxy)‐N,N‐diethylpropionamide], was emphasized in this study. A negative linear correlation was found between the log of the solubility and the log of the association coefficient of these five pesticides with dissolved humic acid derived from peat (peat‐DHA). However, napropamide, which is more water soluble and therefore considered less hydrophobic than lindane (γ‐1,2,3,4,5,6‐hexachlorocyclohexane) and prometryn [2,4‐bis(isopropylamino‐6‐methyl‐thio‐s‐triazine] had a greater extent of association with peat‐DHA, suggesting that hydrophobicity of nonionic pesticides is not the only factor governing their interaction with DOM. When comparing DOM from several sources, dissolved humic acid had a higher affinity than dissolved fulvic acid for napropamide, DDT [1,1,1‐trichloro‐2,2‐bis(p‐chlorophenyl)ethane], and lindane. Association of napropamide with peat‐DHA increased with increasing pH above pH 6.4, decreasing ionic strength, and decreasing charge on cations added to the system. Dissociation studies showed that the interaction between napropamide and peat‐DHA was not fully reversible. The results suggest that the source of the DOM, properties of the solution environment, and reversibility of the interaction should be taken into account when evaluating the interaction between DOM and nonionic pesticides. In addition, dissolved humic and fulvic acid released from two soils showed a different affinity for napropamide compared to bulk soil organic matter when the ability of the whole soil to retain napropamide was expressed on the fraction organic‐carbon‐content basis.
The Degradation of Trichloroethylene in Mixed Methanogenic Cultures
Authors: Baek Nam H. , Jaffe Peter R.
Published: July 2010

Symbiosis between nonmethanogenic fermenters and methanogens, which occurs through a phenomenon called the interspecies hydrogen transfer, can play an important role in the growth of these microorganisms. In the degradation of natural materials, methane production is frequently supported by this interspecies hydrogen transfer from fermenters that degrade the primary substrate, to methanogens that use the hydrogen to reduce carbonate to methane. The objective of this work was to evaluate the role of the fermenters in the degradation of trichloroethylene during methanogenesis. The results show that the fermentation process enhances the anaerobic degradation of trichloroethylene. In addition, it is shown that chloroethane appears as one of the products of the degradation of trichloroethylene by this mixed culture. The production of chloroethane indicates that hydrogenation of the double bond of a chlorinated ethene occurs during the degradation of trichloroethylene by cultures containing nonmethanogenic fermenters and methanogens. The metabolism involved in this degradation process may therefore provide a possible mechanism to completely degrade trichloroethylene under anaerobic conditions, because it is known that chloroethane is degraded rapidly to inorganic carbon.
Acidity Produced by Leguminous Plants through Symbiotic Dinitrogen Fixation
Authors: Liu Wen‐Cheh , Lund L. J. , Page A. L.
Published: July 2010

Red clover (Trifolium prateuse L.), sweet clover (Meliotus alba Medik.), alfalfa (Medicago sativa L.), and crown vetch (Vica villosa Roth) were grown in nitrogen‐free Hoagland's solution in a declining nutrient condition. Increases in acidity of the nutrient solutions were recorded over the experimental period. In general, the excess bases and the excess bases/nitrogen ratio varied considerably among harvests. Significant positive relationships between total N and proton efflux, excess bases and H+ excretion, and dry weight and H+ efflux were observed. The milligrams H+ produced per gram N fixed for the four legumes were 49 for red clover, 43 for crown vetch, 42 for alfalfa, and 37 for sweet clover. By extrapolating the protons produced per gram dry weight in this study to yields commonly observed in the field, annual hydrogen production per hectare would amount to 9.7 kg for red clover, 4.6 kg for sweet dover, 15.2 kg for alfalfa, and 4.5 kg for crown vetch. The amounts of acidity produced per hectare per year calculated from the values of N2 fixation were 5.2 to 14 kg by alfalfa, 4.2 to 9.4 kg by red clover, 3.2 to 7.1 kg by sweet clover, and 3.9 to 6.8 kg by crown vetch. The study demonstrates that production of H+ through symbiotic fixation by legumes is an important source of acidity in agricultural ecosystems. The acidifying effect of legumes could, in the long‐term, result in acidification of the bulk soil causing the downward leaching of exchangeable cations and a decrease in base saturation.
Tolerance of Red Oak and American and European Beech Seedlings to Aluminum
Authors: Thornton F. C. , Schaedle M. , Raynal D. J.
Published: July 2010

The effect of aluminum (Al) on the growth of red oak (Quercus rubra L.), American beech (Fagus grandifolia Ehrh.), and European beech (Fagus sylvatica L.) seedlings was studied in solution culture containing from 0 to 3000 µM Al at pH 4.0. Aluminum had no detrimental effect on biomass of shoots of red oak and American beech. Shoot biomass of European beech was significantly reduced by Al, with greater reductions measured for seedlings grown in lower ionic‐strength media. Root biomass of species did not decline with increasing Al, and actually increased in some Al treatments. Generally, Ca, Mg, and P tissue concentrations of leaves and roots decreased with increasing solution Al for all three species. Even at the lowest solution Al concentration, 500 µM, significant reductions relative to the controls were measured. Of the elements measured, P appeared to be the most strongly correlated with shoot biomass response, having r values of 0.87 and 0.98 for American beech and European beech, respectively. Results from these studies indicate that the risk of direct effects of toxic soil solution Al concentrations on growth of red oak and American beech seedlings is low. However, soil solution concentrations of 500 µM have been reported in Europe and these correspond to the Al level found to significantly reduce shoot biomass of European beech in this study.
Uranium, Vanadium, and Molybdenum in Saline Waters of California
Authors: Bradford G. R. , Bakhtar D. , Westcot D.
Published: July 2010

Analyses of saline water samples from large salt water bodies, agricultural drainage and evaporation ponds, and soil water extracts were used to determine the extent of elevated uranium (U), vanadium (V), and molybdenum (Mo) in agricultural environments of the San Joaquin Valley. Saline water samples and soil extracts were pretreated by chelation and solvent extraction to separate and concentrate, U, V, and Mo for analyses. Mean concentrations of U, V, and Mo were considerably elevated in agricultural drainage and evaporation ponds of the San Joaquin Valley compared to saline waters of Salton Sea and Mono Lake. Relatively high correlation coefficients were observed between U, Mo, and salinity.
Sensitivity of Tree Seedlings to Aluminum: II. Red Oak, Sugar Maple, and European Beech
Authors: Kelly J.M. , Schaedle M. , Thornton F. C. , Joslin J. D.
Published: July 2010

A series of solution culture and greenhouse studies were conducted as part of the ALBIOS project to evaluate the response of northern red oak (Quercus rubra L.), sugar maple (Acer saccharum Marsh.), and European beech (Fagus sylvatica L.) seedlings to Al. Several soil and plant variables were evaluated as possible indicators of plant response to increased Al. Of the soil variables evaluated, 0.01 M SrCl2 extractable Al was found to be well correlated (r = 0.70) with plant response. Changes in root branching frequency were found to be an even more sensitive indicator of potential impact, although routine applications in the field was deemed impractical. Of the three species evaluated, northern red oak was the most sensitive to increasing Al, exhibiting root growth reductions at Al concentrations ranging from 0.12 to 0.28 mM in two separate experiments. The Ca/Al ratio was found to be particularly important in establishing toxicity thresholds for northern red oak with no Al impacts observed when Ca/Al ratio was greater than 4. In low ionic strength solution culture experiments, shoot growth of European beech was reduced by 40% at an Al concentration of 0.5 mM. Foliage tissue Al concentrations tended to be less reliable than root concentrations as predictors of plant response. Comparison of established critical tissue levels (CTL) of Al to tissue data from various field sites indicated that only northern red oak (CTL = ∼6600 µg g−1) may be near impact levels, whereas soil and soil solution data indicate rhizosphere levels generally well below those producing an impact. All results and thresholds must be extrapolated with caution because there are many interacting factors producing a variety of responses in the face of seemingly similar experimental treatments.
Sensitivity of Tree Seedlings to Aluminum: III. Red Spruce and Loblolly Pine
Authors: Raynal D. J. , Joslin J. D. , Thornton F. C. , Schaedle M. , Henderson G. S.
Published: July 2010

Unexplained declines in the growth of both red spruce (Picea rubens Sarg.) and loblolly pine (Pinus taeda L.) have been reported within their natural ranges recently. The possible role of Al phytotoxicity as a causal agent in these declines has been studied extensively. Results of experiments with seedlings grown in solution, sand, and soil indicate minimal involvement of Al in the decline of loblolly pine. However, both controlled studies and field data indicate that reductions in tissue Ca and Mg may occur at Al concentrations well below those causing direct injury. Thus, Al may be involved in reductions in pine growth through interference with nutrient uptake and translocation. Several independent studies demonstrate that Al does directly affect growth of red spruce seedlings at Al concentrations of ≤0.25 mM, a concentration that might approach the range of soil solution Al concentrations measured in native red spruce stands in the Appalachian Mountains (0.1–0.28 mM). In these seedling studies, concentration of Ca and Mg in red spruce roots and foliage were also markedly reduced by relatively low solution Al concentrations. Thus, a contributing role for Al phytotoxicity in red spruce decline, through both direct biomass reduction and indirect effects due to interference with nutrient uptake, appears plausible.
Geochemical Factors Controlling the Mobilization of Inorganic Constituents from Fossil Fuel Combustion Residues: II. Review of the Minor Elements
Authors: Eary L. E. , Rai Dhanpat , Mattigod S. V. , Ainsworth C. C.
Published: July 2010

Past studies of the environmental aspects of fossil fuel waste disposal have focused on determining elemental concentrations, elemental distributions, and empirical rates of elemental extraction. The concentration data for the minor elements (i.e., As, B, Ba, Cd, Cr, Cu, Pb, Mn, Hg, Mo, Ni, Se, Sr, V, and Zn) are extremely variable and are dependent on fuel composition and combustion processes. Studies of elemental extraction rates have provided empirical information on short‐term leaching behavior that is relevant only to a specific waste sample. Extraction studies serve to characterize the initial states of wastes prior to disposal but generally have not provided information on the dominant weathering reactions that will control the long‐term concentrations of minor elements in the disposal environment. We propose that a more useful approach for understanding leachate chemistry involves the consideration of the thermodynamics of specific dissolution/precipitation, adsorption/desorption, and redox speciation reactions that occur during weathering in addition to empirical data. Because fossil fuel wastes are composed of high‐temperature solids that formed under conditions of combustion, this approach can be used to describe the reaction paths governing the alteration of the high‐temperature solids to assemblages of secondary solids and aqueous species that are stable in weathering environments. The depiction of leaching behavior through solubility and speciation relationships rather than through empirical interpretations of extraction rates allows one to establish bounds for the aqueous concentrations of various elements, given information on the chemistry of waste solids and on physical and chemical conditions. The determination of thermodynamic data and application of those data to understanding the leachate chemistry of the minor elements in the disposal environment remains an area where much research is needed.
Application of Radioactive Fallout Cesium‐137 for Measuring Soil Erosion and Sediment Accumulation Rates and Patterns: A Review
Authors: Ritchie Jerry C. , McHenry J. Roger
Published: July 2010

Radioactive fallout 137Cs (cesium‐137) deposited across the landscape from atmospheric nuclear tests is strongly absorbed on soil particles limiting its movement by chemical and biological processes. Most 137Cs movement in the environment is by physical processes; therefore, 137Cs is a unique tracer for studying erosion and sedimentation. Cesium‐137 loss from a watershed has been shown to correlate strongly with soil loss calculated by the Universal Soil Loss Equation (USLE) or measured from small runoff plates. By measuring spatial patterns of 137Cs in vertical and horizontal planes across the landscape, rates of soil loss or deposition can be measured for different parts of a watershed. Even within landscape units, redistribution of soil can be mapped and erosion or deposition rates for different parts of individual fields measured and mapped. Sediment accumulation rates can be measured by comparing the vertical distribution of 137Cs in sediments with the temporal deposition of fallout 137Cs from the atmosphere to locate sediment horizons. Using these dated sediment horizons, sediment accumulation rates can be measured. Interpretations about the location of these dated horizons must consider particle size of the sediments, reworking of deposited sediments, diffusional movement of 137Cs, and time rates of physical process in the sedimentation process. The 137Cs technique can be used to determine sediment accumulation rates in a wide variety of depositional environments including reservoirs, lakes, wetlands, coastal areas, and floodplains. The bibliography shows that 137Cs has been used widely for studying erosion and sedimentation in many different environments around the world.
Soil Nitrate Accumulations following Nitrogen‐Fertilized Corn in Pennsylvania
Authors: Roth G. W. , Fox R. H.
Published: July 2010

Nitrate (NO−3‐N) contamination of surface waters and groundwater in Pennsylvania has made it necessary to evaluate the impact of N fertilization practices for corn (Zea mays L.) on the accumulation of NO−3‐N in the soil. This study was initiated to (i) determine soil NO−3‐N accumulations following the harvest of corn fertilized at various N rates in Pennsylvania, (ii) estimate the soil nitrate accumulation at the economic optimum N rate under a range of conditions, and (iii) estimate changes in soil NO−3‐N over the winter. Soils in nine N response experiments in central and southeastern Pennsylvania and in a long‐term N source experiment in central Pennsylvania were sampled in 30.5‐cm increments to 122 cm following corn harvest in the fall of either 1986 or 1987. Five of these experiments were sampled again the following spring. All experiments were located on limestone‐derived silt loams classified as either Duffield (fine‐loamy, mixed, mesic Ultic Hapludalfs), Hagerstown (fine, mixed, mesic Typic Hapludalfs), or Murrill (fine‐loamy, mixed, mesic Typic Hapludults) soils. Soil NO−3‐N accumulation to 120 cm in the N response experiments, averaged over N rates, ranged from 36 to 295 kg NO−3‐N ha−1. Sites with a history of manure applications generally had greater NO−3‐N accumulation. At economic optimum N (EON) fertilizer rates, estimates of soil NO−3‐N accumulation to 120 cm ranged from 41 to 138 kg N ha−1. Accumulations at the EON averaged 74 kg ha−1 in nonmanured sites and 94 kg ha−1 in responsive, manured sites. Soil NO−3‐N accumulation in two check treatments on manured sites where no yield response to N occurred averaged 169 kg NO−3‐N ha−1. In the longterm experiment, soil NO−3‐N accumulation at the economic optimum N rate in the manured system was greater (135 kg N ha−1) than in the nonmanured system (115 kg N ha−1). Changes in soil NO−3‐N accumulations between fall and spring were variable, but often a substantial accumulation was still present in the spring. The results of this study indicate need for careful N management in manure‐based systems, identification of nonresponsive and potentially polluting sites, and consideration of soil NO−3‐N accumulation in N fertilizer recommendations.
Exchange of Phosphorus from Shallow Sediments at Nine Alberta Lakes
Authors: Shaw J. F. H. , Prepas E. E.
Published: July 2010

Potential exchange of P between sediments and lakewater and particulate sediments and porewater was evaluated in nine eutrophic lakes in Alberta. Lakewater above the sediments, porewater, and sediments were collected from shallow depths during May to August 1986. Lakewater soluble‐reactive P concentrations ([SRP]) were positively correlated with porewater [SRP] (P < 0.01) and negatively with the Fe/P molar ratio in porewater (P < 0.001). Potential release of SRP from sediments to lakewater (by molecular diffusion) was positively correlated with particulate P fractions that are known to exchange P with water (P < 0.01). In porewater, [SRP] was positively correlated with Fe2+ concentration and weakly correlated with pH (P < 0.001 and 0.05, respectively). These results indicate (i) potential transport of P from sediments to lakewater when Fe is not abundant, (ii) common sources and similar mobilities of Fe and P, and (iii) importance of pH in regulation of P exchange between particulate sediments and porewater. No significant relationships (P > 0.05) were found between porewater [SRP] and particulate P fractions. In this study, correlation coefficients were generally low, which suggests (i) the chemical fractionation of particulate sediments failed to isolate the exchangeable P fraction and (ii) partitioning of P within sediments and the release of P from sediments to lakewater are complex processes, only partially regulated by pH and Fe2+ in porewater. To gain better understanding of P release from shallow sediments, future studies should include possible interactions between P and redox potential, Al, Mn, Ca, and S.
A Water Balance Study of Two Landfill Cover Designs for Semiarid Regions
Authors: Nyhan J. W. , Hakonson T. E. , Drennon B. J.
Published: July 2010

The results from several field experiments on methods to control soil erosion, biointrusion, and water infiltration were used to design and test an enhanced landfill cover that improves the ability of the disposal site to isolate buried wastes. The performance of the improved cover design in managing water and biota at the disposal site was compared for 3 yr with that obtained from a more conventional design that has been widely used in the industry. The conventional cover design consisted of 20 cm of sandy loam topsoil over 108 cm of a sandy silt backfill, whereas the improved design consists of 71 cm of topsoil over a minimum of 46 cm of gravel, 91 cm of river cobble, and 38 cm of sandy silt backfill. Each plot was lined with an impermeable liner to allow for mass balance calculation of water dynamics. Results over a 3‐yr period, including 2 wet yr, demonstrated that the improved design reduced percolation of water through the landfill cover by a factor of >4 over the conventional design. This decrease in percolation was attributed to a combination of increased evapotranspiration from the plant cover and the effect of a capillary barrier embedded in the enhanced cover profile in diverting water laterally in the cover. The field data are finally discussed in terms of its usefulness for waste management decisions to be made in the future for both new and existing landfills at Los Alumos, NM, and at other semiarid waste disposal sites.
Selenium Immobilization in a Pond Sediment at Kesterson Reservoir
Authors: Long Robert H. B. , Benson Sally M. , Tokunaga Tetsu K. , Yee Andrew
Published: July 2010

Kesterson Reservoir, Merced County, CA, a disposal facility for agricultural drain water, became the object of intense scientific investigation following discovery in 1983 that Se‐laden agricultural drain water was having serious effects on the reproductive success of waterfowl. A remedial measure involving permanent flooding with low‐Se water, aimed at taking advantage of low Se solubility under reducing conditions, was proposed as a means of limiting Se movement into groundwater and biota. A field experiment was undertaken to evaluate the feasibility of the proposed remedial measure, its impact on the quality of shallow groundwater and for quantifying Se immobilization and transport through a newly flooded pond bottom soil. Extensive soil water and groundwater sampling demonstrated that although initial soluble Se concentrations in the top 1.22 m (4 ft) of soil typically ranged from approximately 1000 to 3000 µg L−1, Se concentrations declined dramatically after flooding and elevated concentrations below 1.22 m were observed at only one of five sampling sites. Analysis of the temporal and spatial changes in the distribution of dissolved Se and Cl− indicated that 66 to 108% of the initial soluble Se present in the top 1.22 m was immobilized shortly after flooding. These estimates were consistent with the low Se concentrations observed in shallow monitoring wells. The extent to which Se immobilization occurred correlated inversely with average pore water velocity. Data presented suggest that reducing conditions in the newly flooded soils lead to the microbially mediated transformation of selenate to less soluble or mobile forms.
Metal Content of Fungal Sporocarps from Urban, Rural, and Sludge‐Treated Sites
Authors: Zabowski D. , Zasoski R. J. , Littke W. , Ammirati J.
Published: July 2010

Fungal sporocarps can influence metal cycling by the uptake of trace metals, which are then readily available for consumption and incorporation into higher food chain levels. This study was conducted to determine if increased sporocarp metal concentrations occurred relative to substrate metal availability in rural, urban, smelter impacted or municipal sewage sludge‐treated sites. Fungal fruiting bodies were collected from rural forests, from urban forests receiving point‐source metal pollution and from forests that had been treated with municipal sewage sludge. Metal concentrations in fungal sporocarps were found to be significantly higher on sewage sludge‐treated sites when all species were considered. Smelter pollution and serpentinite soil, however, were also found to elevate some metals to levels similar to those found at sludge‐amended areas. Overall, individual species appear to be the most important factor for predicting metal uptake from impacted soils and possible inclusion into food chains.
Dissolved and Suspended Solids Transport from Coastal Plain Watersheds
Authors: Hubbard R. K. , Sheridan J. M. , Marti L. R.
Published: July 2010

Excessive amounts of dissolved or suspended solids in surface runoff or base flow may degrade the quality of streams, lakes, or other water bodies. Loads of dissolved and suspended solids in streamflow reflect the quality of water entering via surface runoff or base flow. This study was conducted to determine the concentrations and loads of dissolved and suspended solids in Coastal Plain streamflow; to examine relationships between concentrations, loads, and flow rate; and to determine overall streamflow water quality for these parameters. Dissolved solids and suspended sediment concentrations were determined on weekly or high‐flow storm event streamflow samples collected at gaging stations on three subwatersheds (B, 334.3 km2; F, 114.9 km2; and K, 16.7 km2) of the Little River Watersheds located near Tifton, GA. Dissolved solids concentrations ranged from 19 to 159 mg L−1, and generally decreased as per unit area instantaneous discharge rate increased. Suspended sediment concentrations ranged from 1 to 137 mg L−1, and generally increased as per unit area instantaneous discharge rate increased. Regression analyses showed good relations between log transforms of both dissolved solids load (r2 = 0.97) and suspended sediment load (r2 = 0.79), vs. total monthly runoff. Mean suspended sediment concentrations during high‐flow events were greater than means from the overall data set, while mean concentrations of dissolved solids from these events were reduced relative to the overall data set. The study showed that dissolved solids are the major component of total solids in Coastal Plain streamflow. The mean dissolved and suspended sediment concentrations during the study were 67, 60, and 51 mg L−1; and 14, 17, and 14 mg L−1 for Watersheds B, F, and K, respectively. Overall, the study showed that, as measured on these watersheds, Coastal Plain streamflow is of good quality in terms of both dissolved and suspended solids. This good quality may reflect land‐use practices designed to prevent soil erosion, but primarily reflects the Coastal Plain landform shape, which causes sediments eroded from the uplands to be deposited in the riparian zone before they can enter streamflow.
Leaching of Radionuclides from Decaying Blueberry Leaves: Relative Rate Independent of Concentration
Authors: Sheppard S. C. , Evenden W. G.
Published: July 2010

Leaching of radionuclides from decaying vegetation has not been extensively investigated, especially for radionuclides other than 137Cs. We obtained leaves of blueberry (Vaccinium angustifolium × V. corymbosum) that contained over 25‐fold ranges in Se, Cs, and I concentrations, as well as a small quantity of leaves containing detectable U. All were contaminated by way of root uptake. Leaching took place for a period of 1 yr in the laboratory, using leach water from forest litter. Monthly, measurements were made of the radionuclide contents and decaying leaf dry weights. The data conformed to an exponential decay model with two first‐order components. In no case did the relative loss rates vary systematically with the initial tissue radionuclide concentrations. Loss rates decreased in the order Cs > I > U > dry wt. > Se. Because of the low leaching rate of Se relative to the loss of dry weight, decaying litter may actually accumulate elements such as Se. Accumulation of radionuclides in litter could have important implications for lateral transport, recycling, and direct incorporation into edible mushrooms.
Plant Uptake and Cycling of Trace Elements on Retorted Oil Shale Disposal Piles
Authors: Stark John. M. , Redente Edward F.
Published: July 2010

This study considers some of the environmental hazards posed by high trace element concentrations in plants growing on retorted oil shale disposal piles and the potential for surface accumulation of trace elements via biocycling. Arsenic, B, Cu, F, Mo, and Se concentrations in plants growing on six disposal piles were determined 7 yr following site construction. Disposal treatments consisted of leaving Paraho retorted shale exposed at the surface, leaching exposed retorted shale with 760 mm of water, covering retorted shale with 30, 60, or 90 cm of soil, or a 30‐cm rock capillary barrier and 60 cm of soil. These treatments plus a disturbed soil reference plot (no retorted shale) were seeded in 1977 with three mixtures of native and introduced plant species. In 1983, Mo was present in plants at high enough levels to cause molybdenosis in ruminants. Molybdenum, F, As, and Se concentrations in plants decreased as depth of replaced topsoil increased. Leaching only slightly reduced concentrations in plants. Capillary barrier and 90‐cm treatments were the most effective at reducing plant trace elements concentrations; however, shrubs and legumes from these treatments still occasionally had higher trace element contents than plants growing on disturbed soil reference plots. Legumes had higher concentrations of most trace elements than grasses or shrubs. For this reason species composition had a major effect on total trace element content of stands of vegetation. Rates of movement to the surface via biocycling appear to be relatively slow, although they may continue to increase in the future.
Pendimethalin Volatility following Application to Turfgrass
Authors: Cooper R. J. , Jenkins J. J. , Curtis A. S.
Published: July 2010

Volatilization can be a significant avenue of loss for some pesticides following application to field crops or soil. Volatility following pesticide application to dense turfgrass, however, has not been well documented. This work characterized volatilization of the preemergence herbicide pendimethalin [N‐(1‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine] following application to a Kentucky bluegrass (Poa pratensis L.) turf. Pendimethalin [60% water dispersible granules (WDG)] was applied at 3.4 kg ha−1 with volatilization losses monitored over a period of 15 d. Pendimethalin vapor flux followed a diurnal pattern with maximum daily flux usually occurring 1300 to 1500 h. Maximum flux of airborne residues occurred 1300 to 1500 h. Maximum flux of airborne residues occurred 1300 to 1500 h on the day of application when losses totaled 23.6 g ha−1 h−1. Pendimethalin volatile losses were 4.8% (165 g ha−1) of the original application during the first 24 h following application. Overnight (1900 to 0700 h) volatile losses measured 9.5 and 10.5 g ha−1 on Days 1 and 2 of the experiment (each overnight loss approximately 0.3% of application). Volatile losses during the 48 h following application totaled 6.1%, with an estimated loss of approximately 13% during the 5‐d period following application. Daily volatile loss declined in a diphasic manner over the course of the study, with an initial period of rapid decline in daily vapor flux lasting 5 to 7 d followed by a period of slower decline for the remainder of the study. Dissipation of foliar dislodgeable residues followed a diphasic decline similar to that observed for daily airborne loss, suggesting a relationship between pendimethalin volatilization and foliar dislodgeable residues over time.
Assessment of Management Practices for Reducing Pesticide Runoff from Sloping Cropland in Illinois
Authors: Felsot Allan S. , Mitchell J. Kent , Kenimer Ann L.
Published: July 2010

The influence of tillage system and contouring practice on runoff of soil‐applied alachlor [2‐chloro‐2′,6′‐diethyl‐N‐(methoxymethyl)acetanilide], carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate), and terbufos (S‐[(tert‐butylthio)methyl] O,O‐diethyl phosphorodithioate) from small plots (30 m2) were studied using a rainfall simulator. Plots were planted in corn (Zea mays L.) in 1983, soybean [Glycine max (L.) Merr.] in 1984, and corn in 1985. Runoff was measured during a 60‐min event with a rainfall intensity of 63 mm/h. During 1984, moldboard‐plowed and no‐till systems were studied with rows oriented on the contour or up‐and‐down slope (7–11% slope). Compared to moldboard plow, up‐and‐down slope no‐till and contouring significantly reduced runoff of carbofuran and alachlor. Percentage of applied carbofuran lost in runoff and sediment ranged from 1% (contoured moldboard) to 11% (up‐and‐down slope moldboard). Percentage of applied alachlor lost ranged from 1% (contoured no‐till) to 2% (contoured moldboard). During 1985, the effects of row orientation were evaluated on moldboard‐plow, chisel‐plow, ridge‐till, strip‐till, and no‐till systems. Under up‐and‐down slope conditions, runoff of alachlor and terbufos plus two metabolites (terbufos sulfoxide and terbufos sulfone) was significantly reduced by strip‐till (<1% loss) compared to moldboard‐plow (6% loss). Larger losses of alachlor (2% of applied) from up‐and‐down slope no‐till than from the other conservation tillage systems (1% or less) was attributed to high concentrations in runoff associated with extensive washoff of the herbicide from soybean crop residues. With contouring, ridge tillage also was effective in reducing pesticide runoff (<1% of applied pesticide), and strip‐till held losses to <0.1%. Alachlor and carboforan were translocated from plots largely in moving water, but terbufos and metabolites were recovered mainly in eroded sediment. Although, no conservation tillage system completely eliminated pesticide runoff, losses were most effectively minimized by contoured strip‐till and no‐till, which controlled both water and sediment movement.
Microbial Release of 2,4‐Dichlorophenol Bound to Humic Acid or Incorporated during Humification
Authors: Dec J. , Shuttleworth K. L. , Bollag J.‐M.
Published: July 2010

The microbial release of 14C‐labeled 2,4‐dichiorophenol (DCP) bound to synthetic and natural humic materials or polymerized by enzymes was investigated to evaluate the possibility of future adverse effects if binding or polymerization is used for decontamination purposes. After 12 wk of incubation with microorganisms obtained from a forest soil, the amounts of substances released into the media were very small (maximum 2.2% of the initially bound 14C) without regard to the kind of the polymer into which 14C‐DCP was incorporated. Most of the radioactivity (46.2 to 80.8%) remained bound to the precipitated humic materials or in the DCP‐po!ymer (90.1 to 97.0%). Certain amounts of the released substances evolved in the form of 14CO2 (1.0 to 9.4% from humic materials and 0 to 0.5% from a DCP‐polymer). The rate of mineralization differed depending on the type of DCP binding—surface‐bound or incorporated during synthesis of humic acid—and on the kind of polymer to which 14C‐DCP was attached. The release into the media and 14CO2 evolution for synthetic and natural humic acids was essentially the same. When only DCP was present in the growth medium, the formation of 14CO2 was less than from a DCP‐humic acid complex; this may indicate that 14CO2 from a DCP‐humic acid complex originated mostly from DCP derivatives. The data obtained for DCP did not provide any evidence for a delayed pollution problem associated with polymerization or binding of xenobiotics to humic acids.
Effect of Municipal Sewage Sludge Application on Growth of Two Reclamation Shrub Species in Copper Mine Spoils
Authors: Sabey B. R. , Pendleton R. L. , Webb B. L.
Published: July 2010

One‐year old transplants of fourwing saltbush [Atriplex canescens (Pursh) Nutt.] and mountain big sagebrush [Artemisia tridentata ssp. vaseyana (Rybd.) Beetle] were grown for 9 mo in large greenhouse pots containing copper mine spoil material amended with one of three rates of municipal sewage sludge. Sludge was thoroughly mixed with the soils in some pots and concentrated around the root plug in others. Additionally, some pots were seeded with western wheatgrass (Agropyron smithii Rydb.) to determine whether the presence of grasses would affect shrub response to sludge addition in low pH copper mine spoils. Growth of fourwing saltbush was enhanced from 38‐ to over 300‐fold by the addition of sewage sludge. Growth of big sagebrush was increased over six‐fold. This was likely the result of increased N, P, and K availability, although improved biological and physical properties of the spoil‐sludge mix may also have been factors. The addition of western wheatgrass to pots containing fourwing saltbush caused a decrease in shrub growth, undoubtedly due to competition for nutrients and other plant growth factors. At the conclusion of the study, shrub leaves contained high levels of Cd and Pb, reflecting the high Cd and Pb content of the growth medium. Zinc, Cu, Mn, and Fe levels were also largely higher than are typical for plant tissue. Shrubs grown in pots in which sludge additions were concentrated around the root plug accumulated more heavy metal than did mixed treatments. Grass tissue did not accumulate excessively high quantities of heavy metals, with the exception of Cu.
Plant Uptake of Pentachlorophenol from Sludge‐Amended Soils
Authors: Bellin Cheryl A. , O'Connor George A.
Published: July 2010

A greenhouse study was conducted to determine the effects of sludge on plant uptake of 14C‐pentachlorophenol (PCP). Plants included tall fescue (Festuca arundinacea Schreb.), lettuce (Latuca sativa L.), carrot (Daucus carota L.), and chile pepper (Capsicum annum L.). Minimal intact PCP was detected in the fescue and lettuce by gas chromatography/mass spectrometry (GC/MS) analysis. No intact PCP was detected in the carrot tissue extracts. Chile pepper was not analyzed for intact PCP because methylene chloride extracts contained minimal 14C. The GC/MS analysis of soil extracts at harvest suggests a half‐life of PCP of about 10 d independent of sludge rate or PCP loading rate. Rapid degradation of PCP in the soil apparently limited PCP availability to the plant. Bioconcentration factors (dry plant wt./initial soil PCP concentration) based on intact PCP were <0.01 for all crops, suggesting little PCP uptake. Thus, food‐chain crop PCP uptake in these alkaline soils should not limit land application of sludge.
Soil Denitrification Rates in Four Subalpine Plant Communities of the Sierra Nevada
Authors: Hixson S. E. , Walker R. F. , Skau C. M.
Published: July 2010

The acetylene inhibition method was used to determine soil denitrification rates of a riparian, meadow, forest, and barren site in the eastern Sierra Nevada. Data were collected from these four sub‐alpine plant communities during dawn‐to‐dusk measurement periods in June, August, and October in order to examine denitrification during the dry season. Soil temperature, moisture, organic matter, C, N, C/N ratio, NO3‐N, and pH were measured to assess their effects on denitrification rates. At all sites, denitrification rates varied randomly during each measurement period and were not influenced by variation in any other soil parameter investigated. Comparisons among the four communities revealed that no single site consistently exhibited the highest or lowest denitrification rate throughout the study. Denitrification rates and soil temperatures in the riparian, meadow, and forest communities declined concurrently during the October measurement period relative to those measured in June and August. Declining denitrification rates from June through October paralleled a decrease in soil organic matter in the riparian community, and denitrification rate varied with soil N over the three measurement periods at the barren site. These results suggest that denitrification in wildland soils varies both temporally and spatially, and that soil physical and chemical parameters identified here as influencing this process explain long‐term but not short‐term variations in denitrification rates.
Nitrogen Mineralization and Elemental Availability in Soils Amended with Cocomposted Sewage Sludge
Authors: Sims J. T.
Published: July 2010

Land application of cocomposted sewage sludge (CCSS), produced by the aerobic digestion of municipal refuse and anaerobically digested sewage sludge, represents an alternative use for organic wastes that are currently landfilled, incinerated, or disposed of by ocean dumping. Laboratory and greenhouse studies were conducted with four types of CCSS to determine their suitability for agricultural use, based on mineralizable N and the availability of plant nutrients and certain nonessential heavy metals (Cd, Cr, Ni, Pb). Nitrogen mineralization studies, conducted for 20 wk with three soils amended with 22 Mg/ha of each CCSS type (total N added = 250 to 398 kg N/ha), indicated that immobilization of N could be a serious problem with these composts. Negative values, ranging from −7 to −39 mg/kg, were obtained for net N mineralization (N mineralized adjusted for inorganic N added in the CCSS and mineralized soil N). Additionally, wheat (Triticum aestivum L.) plants grown in the greenhouse for 8 wk with the same CCSS applied at rates of 0, 11, 22, and 44 Mg/ha, and supplemented with 100 mg/kg of N as NH4NO3, exhibited N deficiency symptoms, reduced dry matter production, and lower plant N concentrations. Only slight differences in plant and soil (Mehlich I‐extractable) concentrations of P, K, Ca, Mg, Cu, Cd, Cr, Ni, and Pb were noted among CCSS types in the greenhouse study. The CCSS rate also had little influence on plant and soil concentrations of these elements. Soil pH, however, was increased by a lime‐amended CCSS, resulting in significant decreases in plant concentrations of Mn nd Zn. In summary, results from laboratory and greenhouse studies suggest that, when applied at agronomic rates, these composts can produce satisfactory plant growth, if adequate amounts of supplemental N fertilizers are applied, and that increases in soil and plant concentrations of nonessential heavy metals should not be a limiting factor in compost use.
Productivity of Clay Tailings from Phosphate Mining: II. Forage Crops
Authors: Mislevy P. , Blue W. G. , Roessler C. E.
Published: July 2010

Phosphate mining in Florida produces phosphatic clay and quartz‐sand tailings waste products. Presently there are about 41 000 ha of phosphatic clay (slime ponds) in Florida. These clays contain no phytotoxic materials, are high in most plant nutrients, and average about 460 g moisture kg−1. A split‐plot field experiment was conducted to study forage yield, quality, plant nutrient concentrations, changes in soil nutrients, and 226Ra contents of 12 grass‐N source treatments. The treatment combinations (i) bahiagrass (Paspalum notatum Fluegge var. saurae Parodi ‘Pensacola’) + N, (ii) bahiagrass + white clover (WC) (Trifolium repens L. ‘Arcadia’), (iii) stargrass (Cynodon nlemfuensis Vanderyst var. nlemfuensis ‘Florico’) + N, (iv) Florico stargrass + WC, (v) Florico stargrass + alfalfa (Medicago sativa L. ‘Florida 77’), (vi) Florico stargrass + carpon desmodium (Desmodium heterocarpon (L.) D.C. ‘Florida’), (vii) Limpograss [Hemarthria altissima (Poir) Stapf et. C.E. Hubb. ‘Floralta’] + N, (viii) Limpograss + WC, (ix) Stargrass (C. nlemfuensis Vanderyst var. nlemfuensis ‘Florona’) + N., (x) Florona stargrass + WC, (xi) Florona stargrass + red clover (Trifolium pratense L. ‘Nolins’), and (xii) Florona stargrass + alfalfa, were grown on dry phosphatic clay with and without a 50 mm surface layer of quartz‐sand tailings. Nitrogen (500 kg ha−1 yr−1) was the only fertilizer element applied on grasses. No fertilizer was applied on legumes during the 4‐yr period. Results indicated that Floralta hemarthria + N, Florona stargrass + N, and Florona stargrass + alfalfa produced highest dry‐forage yields averaging 20.8, 18.1, and 17.7 Mg ha−1. Florico stargrass + WC and Floralta hemarthria + WC had annual averages of 233 and 211 g CP kg−1 and 769 and 751 g IVOMD kg−1, respectively. Grass + N treatments were about 5 to 10 percentage units lower in CP than grass + legumes. Forage mineral concentrations for P, K, Ca, Mg, Mn, Cu, Zn, and Fe, ranged from 1.3 to 39 times higher than required for growing and finishing cattle (Bos sp.). Mehlich I‐extractable soil P (1650 mg kg−1), Ca (4588 mg kg−1), and Mg (1130 mg kg−1) were very high and changed little after 4 yr of forage production. Forages had a differential uptake of 226Ra with Florona stargrass + N (1.28 pCi g−1) having the highest uptake and Pensacola bahiagrass + N (0.32 pCi g−1) having the lowest uptake. Radium 226 in the phosphatic clay was 22 pCi g−1, which was 80 times higher than levels in an unmined Spodosol; however, plant uptake was three times higher than plants grown on unmined soil. Data indicated that phosphatic clays are a fertile resource that can be used for forage production.