bluuebunny/crossref_metadata_2025_split huggingface dataset:
Drinking Water from Agriculturally Contaminated Groundwater
Authors: Goodrich James A. , Lykins Benjamin W. , Clark Robert M. 
Published: July 2010

AbstractSharp increases in fertilizer and pesticide use throughout the 1960s and 1970s along with generally less attachment to soil particles may result in more widespread contamination of drinking water supplies. The purpose of this study was to highlight the use of agricultural chemicals and their occurrence in groundwater while focusing on the engineering processes available for removing them to acceptable limits for consumers. Through various case studies and field‐scale research projects, several different drinking water treatment technologies have been evaluated for their capability removing various groundwater contaminants. Both central treatment and individual household point of entry devices were studied. Treatment options vary depending on the types of contaminants to be removed. Best available technology consists of ion exchange or reverse osmosis for removing nitrates, granular activated C for removing non‐volatile synthetic organics, and air stripping for volatile synthetic organics. Since there is no single treatment for all contaminants, a homeowner or individual community will have to evaluate their particular situation and possibly select a treatment scheme or combination of technologies to provide the best cost‐effective solution.
Assessing the Spatial Distribution of Evapotranspiration Using Remotely Sensed Inputs
Authors: Moran M. Susan , Jackson Ray D. 
Published: July 2010

AbstractThe evaporation of water from soil and plant surfaces is of vital environmental interest. The importance of this process becomes apparent when one considers that the scales involved range from water loss from leaf stomata to the circulation of the planetary atmosphere. Since the launch of the first earth observing satellite in 1972, the idea of using remotely sensed data to evaluate the spatial distribution of evaporation has moved from the conceptual to the developmental phase. Problems that currently impede the development of operational systems include spatial resolution, atmospheric interference, estimation of aerodynamic resistance, spatial extrapolation of ground‐based meteorological data, partial vegetation cover, and the extension of instantaneous values to daily totals. In this review, efforts to evaluate evaporation using remotely sensed data on both local and regional scales are reviewed, and some impediments that must be resolved before an operational system can be developed are discussed.
Evaluation of Methods for Characterizing Carbofuran Hydrolysis in Soil
Authors: Parkin T. B. , Shelton D. R. , Robinson J. A. 
Published: July 2010

AbstractThe objective of this study was to develop a method that could be applied to investigations of soil/environmental factors influencing the spatial and temporal variability of carbofuran hydrolysis in field soils. Two factors were considered: (i) soil handling and pesticide application, and (ii) the method of data summarization. Three soil handling/pesticide treatments were evaluated: (i) sieved soil/sprayed pesticide application, (ii) injected pesticide application/sieved soil, and (iii) injected pesticide application/intact core incubation. This last method was developed to mimic field conditions where high localized concentrations of carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate) occur as a result of banded application of granular carbofuran at planting time. For all three treatments sigmoidal 14CO2 production kinetics were observed. Several mathematical models for describing sigmoidal product appearance data were evaluated and a general saturation model was found to yield the best fit. Using parameter estimates obtained from this model in statistical tests, we found that the intact core soil treatment yielded significantly longer half lives for carbofuran degradation. Additional experimental evidence suggests that soil structure of the intact cores retarded diffusion of the 14CO2 produced from carbofuran degradation and influenced the kinetic pattern observed.
Hydrolysis and Free Radial Mediated Degradation of Phosphonates
Authors: Schowanek Diederik , Verstraete Willy 
Published: July 2010

AbstractWhile studying the biodegradation and environmental fate of phosphonates, two almost undocumented nonbiological degradation processes acting on the stable C‐P bond were observed. Under test conditions comparable to the environmental situation, phosphonates in solution are prone to a slow light‐independent hydrolytic cleavage of the C‐P bond(s). The process requires divalent cations, aerobic conditions, and is particularly active on N‐containing phosphonates. Highest hydrolysis rates, up to 1% phosphonate‐P converted to inorganic phosphate per day, were measured with the polyphosphonates. Second, C‐P bonds in all phosphonates can efficiently be cleaved, also with release of orthophosphate, by means of physicochemically generated free radicals. The riboflavin/light and Cu2+/H2O2 systems were more efficient than the Fenton reagent (Fe2+/H2O2) in this respect. Both processes are likely to contribute to the removal of xenobiotic phosphonates in the environment, particularly in the absence of photo‐ and biodegradation.
Selenium Mobility in Irrigated Soil Columns as Affected by Organic Carbon Amendment
Authors: Neal Rosemary H. , Sposito Garrison 
Published: July 2010

AbstractSamples of two agricultural soil profiles were collected from the western San Joaquin Valley, CA, and packed into 1.5‐m columns. The soils were leached sporadically over 9 wk with an aqueous solution containing selenate and subjected to two different chemical environments in order to investigate the effects of an added C source and intermittent irrigation on the fate of applied Se. Evaluation of the soluble Se present in the soil columns at the end of the leaching experiments showed the movement of Se to be retarded with respect to that of the leaching solution, and this was attributed to the effect of intermittent irrigation on the behavior of Se in the soil columns. Under control conditions, soluble Se was predominantly in the selenate form, whereas the inclusion of a C amendment resulted in reduced total soluble Se in the upper portions of the columns and transformation to organically associated Se. Elevated concentrations of soluble Mn were found where selenate had transformed to selenite and organically associated Se, indicating the possibility of localized reduction processes.
Exposing Loblolly Pine Seedlings to Acid Precipitation and Ozone: Effects on Soil Rhizosphere Chemistry
Authors: Ruark G. A. , Thornton F. C. , Tiarks A. E. , Lockaby B. G. , Chappelka A. H. , Meldahl R. S. 
Published: July 2010

AbstractRhizosphere and nonrhizosphere soils were sampled in association with the roots of field‐grown, 1‐year‐old loblolly pine (Pinus taeda L.) that had been exposed to simulated acidic precipitation and O3 treatments. Soil samples adjacent to roots and from the bulk soil were analyzed separately for H, Al3, Ca2, and Mg2 concentrations. For the acid precipitation treatment, H levels were significantly greater in the rhizophere compared with the bulk soil, but no clear trend could be attributed to acidic precipitation levels. Hydrogen ion concentrations associated with the O3 levels, at times, differed significantly by treatment, butnot between rhizosphere and bulk soil. Rain pH and 3 level produced no statistically significant distinction between rhizosphere and nonrhizosphere soil for Al3, Ca2, or Mg2. However, after combining rhizosphere and nonrhizosphere soil samples, Al3 concentrations were found to generally increase as rain pH decreased, whereas Ca2 and Mg2 followed the opposite pattern. No such pattern for O3 level was apparent. Significant interactions between acid precipitation and O3 treatments were not detected.
Seasonal Variation of Selenium in Outdoor Experimental Stream‐Wetland Systems
Authors: Allen Kathleen N. 
Published: July 2010

AbstractTwo outdoor experimental stream‐wetland systems were exposed continuously to 10 µg/L Se(IV) over a 2‐yr period. A seasonal variation in the water column Se concentration was found in wetlands; a comparable variation was not observed in the stream segments. Water column Se was never reduced by more than 20% in the streams, but was reduced by greater than 90% in midsummer in the wetlands. Accumulation of Se in plants was much higher in the wetlands than in the streams, particularly in duckweed (Lerana minor). The deposition of Se in sediments was extremely variable within the wetlands.
Wind Flow within Open‐Top Growth Chambers and the Gas Exchange Implications
Authors: Flesch T.K. , Grant R.H. 
Published: July 2010

AbstractField studies of atmospheric pollutant effects on plants commonly use an open‐top plant growth chamber (OTC). Altered wind flow characteristics within an OTC may create aerodynamic and boundary layer transport resistances (ra and rb) which differ from field values, complicating the extension of OTC results to field conditions. An OTC was placed in an enclosed area and the wind velocity was measured at five heights at nine locations using a triple hot‐film sensor. Measurements were made in an empty OTC and at two different surface roughnesses. The flow was turbulent, highly variable with location, and had well‐defined vertical and horizontal circulation patterns. Average wind speed in empty OTC ranged from 0.28 to 1.33 m s−1. Increased roughness decreased the mean flow speed but had little effect on the turbulence level or the circulation pattern. The flow within the OTC was used to estimate the ra and rb for O3 uptake in a hypothetical soybean [Glycine max (L.) Merr.] plant canopy, a representative low stomatal resistance species. Results showed that the variable flow in the OTC results in widely varying rb values within the OTC itself, depending on actual physical location within the chamber. In addition, the OTC ra and rb would differ from field values under typical meteorological conditions. For plants with low stomatal resistance this could create significant differences in gaseous uptake for individual plants within the OTC as well as for the average plant in the OTC vs. that in the field.
Effects of Acidity of Simulated Rain on the Fruiting of ‘Summerred’ Apple Trees
Authors: Rinallo C. 
Published: July 2010

AbstractThe effects of rain acidity on field‐grown ‘Summerred’ apple trees (Malus domestica Borkh) under natural conditions were investigated. One group of four trees was exposed to ambient rainfall. Four other groups were covered with rainshields and received water, pH 5.6, 4, and 3, respectively, as simulated rain. Simulated acid rain, particularly at pH 3, adversely affected fruit production in terms of individual fruit weight, fruit set, fruit appearance (necrosis and russetting of the peel) and dry weight. Ambient rain was not found to cause significant reductions in apple fruit production in this study.
Ion Enrichment of Snowmelt Water by Processes within a Podzolic Soil
Authors: Hazlett P.W. , English M.C. , Foster N.W. 
Published: July 2010

AbstractIon concentrations in snowmelt runoff, forest‐floor percolate and mineral‐soil percolate collected in a tolerant hardwood forest at the Turkey Lakes Watershed, ON, were determined during the spring snowmelt of 1986. The results were examined to assess the modification of snowmelt water after contact with the forest soil. Concentrations of NO3− increased from 17 to 201 µmolc L−1 and SO42− increased from 25 to 107 µmolc L−1 as meltwater passed through the organic layers and the upper mineral‐soil horizons. Mineralization of organic N and S, and desorption of SO42− from the soil, provide sources of these ions for leaching during the snowmelt period. Ion‐exchange reactions in the forest floor and upper mineral soil resulted in a decrease in H+ and an increase in Ca2+ concentration in solution. In the steep topography of this forested basin, the altered snowmelt solutions are rapidly transported downslope towards the aquatic system by lateral flow. Processes within the forest soil may therefore play an important role in determining the effects of snowmelt water on surface water chemistry in the spring.
Herbicide and Tracer Movement in Soil Columns Containing an Artificial Macropore
Authors: Czapar G.F. , Horton R. , Fawcett R.S. 
Published: July 2010

AbstractPreferential flow has been shown to be an important mechanism affecting water and solute movement in some soils. The movement of agricultural chemicals to groundwater is of special concern. Soil columns containing an artificial macropore were used to study alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide], cyanazine [2‐{[4‐chloro‐6‐(ethylamino)‐1,3,5‐triazin‐2‐yl]amino}‐2‐methyl‐propanenitrile], pendimethalin [N‐(1‐ethylpropyl)‐3,4 dimethyl‐2,6 dinitrobenzenamine], and chloride movement. Packed columns were modified by removing a 6‐mm diam. core from the center. Herbicides and chloride were applied to the soil surface and columns were irrigated with 63 mm of a 0.0075 M calcium sulfate solution. Initial chloride breakthrough occurred much sooner in columns with a continuous macropore than in columns with either a partial or no macropore. Total chloride loss in column drainage, however, was less in columns containing a continuous macropore than in those without a continuous macropore. In contrast, alachlor, cyanazine, and pendimethalin were only detected in drainage from columns with a continuous macropore. Because herbicides were not detected in column drainage unless a continuous macropore was present, leaching studies using packed soil columns may significantly underestimate the extent of herbicide movement through a structured soil. Pesticide leaching experiments using soil columns with an artificial macropore may provide estimates that are more representative of field behavior and could be used to supplement current pesticide mobility studies required by the USEPA to support product registration.
Effects of Open‐Top Chambers on ‘Valencia’ Orange Trees
Authors: Olszyk D.M. , Takemoto B.K. , Kats G. , Dawson P.J. , Morrison C.L. , Preston J. Wolf , Thompson C.R. 
Published: July 2010

AbstractOpen‐top field chambers are the most widely used technology for evaluating the impacts of air pollutants on vegetation. This study was conducted to evaluate the long‐term effects of chambers on Valencia orange trees (Citrus sinensis [L.] Osbeck). The trees were exposed to ambient ozone (O3) for 51 months in large (4.3‐m diam. by 2.9‐m high) nonfiltered open‐top chambers (NF) and in ambient air without chambers (AA). During this period, the 12‐h daytime (M12) average O3 concentration was approximately 8% lower, and the cumulative O3 exposure for hourly average concentrations >0.1 µL L−1 (SUM10) was 29% lower than for NF than for AA trees. By December 1984 (after eight months in chambers), canopy volume for NF trees was 67% greater than for AA trees; and by March 1988 canopy volume for NF trees was 104% greater than for AA trees (P < 0.001). Specific leaf areas (cm2 g−1) were larger for NF than AA trees (P < 0.05). Total harvestable fruit weight combined for years 1986, 1987 and 1988 was 98% higher for NF than for AA trees (P < 0.01). The higher yield for NF trees was associated with lower immature fruit drop, especially during the growing seasons prior to the 1986 and 1987 harvests (P < 0.01). Warm season (April–October) rates of stomatal conductance and transpiration were 14 and 12% lower, respectively, for NF than AA trees; which coincided with 29% more negative leaf water potentials for NF than AA trees (P < 0.05) . In contrast, cool season net photosynthetic rates were 18% lower for NF than for AA trees, and starch concentrations were 31% higher in leaves from NF compared to AA trees in February 1988 (P < 0.05). Overall, the yield increases for NF compared to AA trees could, in part, be accounted for by decreased flux of O3 into leaves (based on decreased O3 exposure and leaf conductance). However, other factors, i.e., increased tree growth, altered leaf C allocation, and lack of wind stress occurring only in chambers, likely contributed to higher NF tree yields.
Selective‐Placement Burial of Drilling Fluids: I. Effects on Soil Chemical Properties
Authors: McFarland Mark L. , Ueckert Darrell N. , Hons Frank M. , Hartmann Steve 
Published: July 2010

AbstractBurial of spent drilling fluids used in petroleum and natural gas exploration was evaluated for reducing soil contamination caused by conventional, surface disposal of these wastes on arid and semiarid rangelands. Simulated reserve pits at two locations provided burial depths of 30, 90 (with and without a 30‐cm capillary barrier of coarse limestone), and 150 cm below the surface, with sequential replacement of stockpiled subsoil and topsoil. The drilling fluids contained extremely high concentrations of soluble salts [electrical conductivities (EC) = 155–185 dS m−1], with Na and Cl being the dominant soluble ions. Upward migration of contaminants was evaluated over a 20‐month period. Soluble salts migrated upward 15 to 30 cm into the overlying soil, and salt movement appeared to be governed to a greater extent by diffusive rather than convective flow mechanisms. Capillary barriers of coarse limestone effectively reduced salt movement at one of the two sites. Sodium, Ca, and Cl were the dominant mobile ions. Exchangeable Na percentages did not increase in soil increments > 15 cm above buried drilling wastes. Barium, Cr, Cu, Ni, and Zn in drilling fluids did not migrate into overlying soil. Movement of contaminants was similar where fourwing saltbush [Atriplex canescens (Pursh) Nutt.], a deep‐rooted shrub, and buffalograss [Buchloe dactyloides (Nutt.) Engelm], a hallow‐rooted grass, were used for revegetation. Selective‐placement burial of drilling fluids offers an effective and environmentally sound alternative to conventional surface disposal. The probability of upward movement of excessive soluble salts into the plant root zone appears greater for 30‐cm burial, compared to 90‐ or 150‐cm burial, because of greater soil water contents at the soil/waste interface and greater upward water potential gradients in the surface 30 cm.
Biotechnology and Hazardous Waste Treatment
Authors: Stroo Hans F. 
Published: July 2010

AbstractDespite considerable speculation and research on the potential for biotechnology to improve the treatment of hazardous wastes, little progress has been made to date in developing commercially available products and processes. This paper examines the current state of the art and the progress to date, as well as the barriers to biotechnological advances in hazardous waste treatment. The potential applications of biotechnology are also discussed, in terms of the contaminated matrix, the type of reactor technology used and the types of compounds present. The most promising areas for technology development efforts are identified, as well as the critical issues which must be addressed in moving from laboratory‐scale testing to the development of commercially‐viable technologies.
Cadmium Availability and Extractability from Sewage Sludge as Affected by Waste Phosphatic Clay
Authors: Gonzalez R.X. , Sartain J.B. , Miller W.L. 
Published: July 2010

AbstractDisposal of sewage sludge containing high levels of heavy metals invokes environmental concerns. Due to previous phosphate rock mining, large reserves of waste phosphatic clay exists in Florida. The objective of this study was to determine the feasibility of disposing contaminated sewage sludge in waste phosphatic clay ponds. In this study, sewage sludge containing 550 mg Cd/kg was utilized as a soil amendment. Application rates corresponding to 0, 6.25, 12.5, 25.0, 50.0, 75.0 and 100 kg Cd/ha were used on two soils in a glasshouse experiment to determine the influence of waste phosphatic clay (SCM) on the uptake and extractability of Cd. The soils were sand tailings and a 4:1 mixture of tailings and waste phosphatic clay (SCM). Alfalfa (Medicago sativa) was grown for 155 d and dry matter clippings were taken three times. The DTPA‐extractable Cd was determined and single degree of contrasts was used to compare treatment means, sludge application rates, and plant tissue Cd concentrations. Results indicated that Cd uptake by alfalfa grown on sludge‐amended soils was suppressed by the presence of waste phosphatic clay. Extractable levels of Cd decreased with time on sludge‐amended SCM while remaining relatively the same on sludge‐amended tailings. Waste phosphatic clay suppressed the uptake of Cd added as sewage sludge. Land application of sewage sludges at waste clay disposal sites could improve soil conditions and help solve the problem of sludge disposal in an environmentally sound manner.
The Rhode River Watershed: Phosphorus Distribution and Export in Forest and Agricultural Soils
Authors: Vaithiyanathan P. , Correll David L. 
Published: July 2010

AbstractTo evaluate the effects of land use on P transport and transformation in the Atlantic coastal plain, we examined the distribution and fractionation of P in forested and agricultural soils of the Rhode River watershed and their export rates. Nearly 70% of P in forest soils was bound in organic forms. Fractionation studies reveal that cultivation and fertilizer P application increased total and inorganic P content and decreased organic P content of the soils. About half of the increase in the inorganic P content of the agricultural soils is due to the mineralization of organic P during cultivation and the rest is probably due to fertilizer P application. The inorganic phosphates in the forest and agricultural soils are chiefly associated with Fe either as iron phosphates or as phosphates adsorbed on the iron oxide surfaces. The agricultural watershed had a higher P export (46.3 g P ha−1 wk−1) compared to the forested watershed (5.96 g P ha−1 wk−1). Particulate P dominated the P export from both watersheds. Variations in the P flux from the watersheds was correlated to changes in water discharge. The discharge pattern of organic and inorganic P forms from the watersheds are highly related to their soil P composition.
Effects of Fluidized Bed Combustion Residue on the Health and Performance of Sheep Grazing Hill Pastures
Authors: Vona L.C. , Meredith C. , Reid R.L. , Hern J.L. , Perry H.D. , Bennett O.L. 
Published: July 2010

AbstractThe effect of application of fluidized bed combustion residue (FBCR), a product resulting from the removal of S from high‐S coals, was compared with application of dolomitic limestone, or no treatment, on the performance of ewes (Ovis aries) grazing hill pastures over a 3‐yr period. Pastures were treated with FBCR and limestone twice per annum and ewes with their lambs grazed at two stocking rates from late April to October. Herbage analysis showed increases in Ca concentration in FBCR and lime‐treated pasture vs. control, a higher level of S in FBCR vs. lime‐treated herbage, but no differences in microelement concentrations due to treatment. There were no differences in weight gains of either ewes or lambs within years due to treatment, and no effect of treatment on blood hematocrit levels. Ewes were killed before and after the 3‐yr trials, and lambs were sacrificed before and after each grazing season, to determine the effect of FBCR application on mineral accumulation in the carcass or organs of the animals. There were either no differences or small differences in the concentrations of macro‐ and microelements in the carcass, liver, and kidney of ewes and lambs associated with treatment, and tissue concentrations of elements were within normal ranges. The results confirm studies with rats (Rattus rattus), hamsters (Mesocricetus auratus), and pigs (Sus scrofa) showing that treatment of agricultural soils with high levels of FBCR as a liming or fertilizing agent causes no adverse effects on composition of food crops or herbage, or on the health and productivity of animals consuming diets produced on such soils.