bluuebunny/crossref_metadata_2025_split huggingface dataset:
Persistence of Carbofuran and Molinate in Flooded Rice Culture
Authors: Johnson W. G. , Lavy T. L. 
Published: July 2010

AbstractField studies were conducted on silt loam and silty clay soils to determine the persistence of carbofuran (2,3‐dihydro‐2,2‐dimethyl benzofuran‐7‐yl methylcarbamate) and molinate (S‐ethyl hexahydro‐1H‐azepine‐1‐carbothioate) in the soil and water associated with rice (Oryza sativa L.) production in Arkansas. Paddy‐rice plots were established with earthen levees surrounding each plot and standard cultural practices were followed concerning rice production. Granular formulations of these pesticides were applied 4 d following establishment of the permanent flood at the tillering stage of rice growth. Samples of water and soil were taken at various intervals until 49 days after application (DAA) and analyzed with gas chromatography. Carbofuran was not detected in paddy water after 28 DAA. By 21 DAA, >90% of the applied molinate had dissipated, but detectable levels (0.0012 mg L−1) of residues remained in paddy water through 49 DAA. Both pesticides dissipated rapidly from paddy soil for approximately the first 14 DAA, probably due to solubilization of the granules into the overlying paddy water. Both pesticides had estimated time required for dissipation of 50% of the initial concentration (DT50s) of 10 d in paddy water and paddy soil. Molinate dissipation from paddy soil slowed dramatically after the initial rapid phase. The carbofuran metabolite 3‐keto carbofuran (2,3‐dihydro‐2,2‐dimethyl‐3‐ketobenzofuranyl‐N‐methyl carbamate) was not detected in any water samples, but was detected in 6% of the soil samples. The metabolite 3‐hydroxy carbofuran (2,3‐dihydro‐2,2‐dimethyl‐3‐hydroxy‐benzofuranyl‐N‐methyl carbamate) was detected in 2% of the water samples and 7% of the soil samples. In both cases the concentrations found were slightly above the lower limits of detectability (0.005 mg L−1 for water and 0.01 mg kg−1 for soil).
Persistence of Triclopyr and 2,4‐D in Flooded and Nonflooded Soils
Authors: Johnson W. G. , Lavy T. L. , Gbur E. E. 
Published: July 2010

AbstractField studies were conducted on silt loam and silty clay soils to determine the persistence of triclopyr ([(3,5,6‐trichloro‐2‐pyridinyl) oxy] acetic acid) and 2,4‐D (2,4‐dichlorophenoxy acetic acid) in the soil and water associated with rice (oryza sativa L.) production in Arkansas. Liquid formulations of these herbicides were applied postemergence to (i) paddy rice, (ii) rainfed lowland rice, and (iii) bare ground. Samples of soil and water were taken at various intervals until 49 days after application (DAA) and analyzed by gas chromatography. Dissipation of both herbicides was rapid with initial dissipation of 50% of the initial concentration, DT50s, in paddy water, dryland‐rice soil, and bareground soil being 10 d or less. Neither herbicide was detected in water later than 28 DAA. Both herbicides were slightly more persistent in soil than in water. 2,4‐D was slightly more mobile in the soil of all three cultural systems.
Physical and Chemical Characteristics of Selected U.S. Municipal Solid Waste Composts
Authors: He Xin‐Tao , Logan Terry J. , Traina Samuel J. 
Published: July 2010

AbstractMunicipal solid waste (MSW) composting has been increasingly recognized as a promising alternative for solid waste management. Because of the variation in both geographic origin (thus feed stock) and composting technology, the properties of MSW composts generated in various regions are likely to be different. In this study, 10 composts were collected from different facilities throughout the USA. Elemental composition and some physical properties were determined. Trace elements and organic C were partitioned into water soluble, exchangeable, complexed, organically bound, mineral particulate, and residue forms based on sequential extraction with H2O, 1 M KCl, 0.1 M Na4P2O7, 0.1 M NaOH, and 4 M HNO3, respectively. Substantial variabilities were observed in both chemical and physical properties among the MSW composts generated in different facilities. Our results indicate that the trace element contents of MSW composts are in general lower than the average trace elements reported for sewage sludges, and below the pollutant concentrations (PC) for sewage sludges regulated by USEPA. The exception is for Pb, which was higher in some of the MSW composts than the average Pb content in sewage sludges and exceeds the PC. Solid particulate was the dominant form of Cd, Mn, Cu, and Pb, but the majority of Zn was organically complexed. Both solid particulate and residue were dominant forms of compost Cr and Ni. The differences in distribution patterns of trace elements in the MSW composts studied indicate that these elements will vary in their potential mobility and bioavailability in the environment.
Phosphate Removal by Peat from Peat Mining Drainage Water during Overland Flow Wetland Treatment
Authors: Heikkinen Kaisa , Ihme Raimo , Osma Anna‐Mari , Hartikainen Helinä 
Published: July 2010

AbstractOverland flow technique, which involves conducting wastewater across a natural mire, has during the recent years been widely used in Finland to decrease the loading of P and other elements from peat mining areas to the watercourses. In this study the applicability of laboratory tests in estimating the P retention by overland flow areas was assessed at a site in northern Finland. The ability of peat to retain PO4‐P was determined by adsorption isotherms, and the data were compared with the actual decreases in P loads obtained in the field. The PO4‐P retention curves obeyed rather well the conventional adsorption models, which suggests that sorption can be an important mechanism removing PO4‐P from the peat mining drainage water during overflow treatment. The Freundlich equation gave a better fit to the P sorption than did the one‐surface Langmuir model. The constants describing the sorption characteristics of the peat showed spatial and temporal variation. They indicated, however, that the theoretical effective P sorption time for the overland flow area can be 20 to 25 yr. The ability of peat to retain P increased with increasing concentrations of oxalate extractable Fe and Al. Sorption reactions were found to be important in the annual decreases in PO4‐P from drainage waters in an overland flow area, but their efficiency in removing P from the peat mining drainage water appears to depend on hydrological conditions. In the first experimental year, the sorption calculated from the isotherm data amounted to 60% of the retention obtained in the field. Owing to the high flow conditions in the second year, the decrease in the loading of P in the field was decisively lower than estimated.
An Alkaline Oxidation Method for Determination of Total Arsenic and Selenium in Sewage Sludges
Authors: Zhu Baojin , Tabatabai M. A. 
Published: July 2010

AbstractA simple and precise method was developed for determination of total As and Se in sewage sludges by using hydride‐generation atomic absorption spectrometry (HGAAS). It involves boiling a 50‐mg sample with sodium hypobromite (NaOBr) solution to dryness in a sand bath (260–280°C), extraction of the As and Se in the digest with 1.25 M H2SO4, and determination of these elements by HGAAS after reducing As(V) and Se(VI) to As(III) and Se(IV), respectively. The proposed method gives quantitative recovery of As and Se in standard reference materials (96–103%) and of these elements added to sewage sludges (95–100%). The average results of As (9.8 mg/kg) and Se (7.5 mg/kg) in 12 sewage sludges determined by the proposed digestion method agreed closely with those obtained by the acid digestion methods recommended by USGS and USEPA. Tests with 13 metals indicated that, at the concentrations expected in sewage sludges, none of the metals interfered with determination of As and Se by the proposed method. A single operator can complete analysis of one of the elements in 40 samples in a normal working day, or both elements in 1.5 d.
Plant Growth Inhibition by Soluble Salts in Sewage Sludge‐Amended Mine Spoils
Authors: Rodgers Cassandra S. , Anderson Roger C. 
Published: July 2010

AbstractThe growth response of prairie switchgrass (Panicum virgatum L.) was compared in strip mine spoil amended with various levels of anaerobically digested waste‐activated sewage sludge (0, 56, 111, 222, or 333 dry Mg ha−1) and commercial fertilizer, pure sludge, and glasshouse soil. Plants were grown in a growth chamber and substrates were maintained at field capacity during the study. Soluble salt concentrations of the substrates increased linearly as a function of sludge amendment and were within the range known to inhibit the growth of many plant species at the high levels of sludge application. There was, however, a linear response of biomass production to increasing levels of sludge amendment. Maintaining substrates at field capacity apparently prevented the high concentration of soluble salts from inhibiting plant growth. The increased biomass yield associated with sludge application was likely due to the increased availability of inorganic nutrients associated with sludge amendment.
Competitive Surface Complexation Reactions of Sulfate and Natural Organic Carbon on Soil
Authors: Kooner Z. S. , Jardine P. M. , Feldman S. 
Published: July 2010

AbstractThe ecological implications of subsurface SO2−4 loading on nutrient cation leaching, acidification, and the destruction of concrete containers used to store low‐level radioactive waste, has been thoroughly addressed. Processes favoring SO2−4 adsorption by the subsurface matrix tend to alleviate these adverse ecological conditions and this has been investigated to a lesser extent. In this study, the adsorption of SO2−4onto several soil types with indigenous SO2−4 and organic carbon removed, was measured as a function of pH in the presence and absence of added natural organic matter (NOM). Sulfate adsorption was strongly pH dependent and the presence of >2 mg L−1 NOM resulted in a consistent decrease in sulfate adsorption over the pH range 4.5 to 8. The tendency of these soils to adsorb SO2−4 was related to their large quantity of Fe‐oxides and the presence of kaolinite in the <2‐µm clay fraction. A surface complexation model based on electrical double layer theory was used to model the adsorption behavior of sulfate. A single reaction involving the adsorption of SO2−4 onto positive or neutral surface sites (XOH + H+ + SO2−4 = XSO−4 + H2O) as an inner‐sphere complex proved successful in describing the adsorption of sulfate under the experimental conditions. The estimated value of the intrinsic equilibrium constant (K) for the above reaction was of the order 1010 suggesting strong sulfate adsorption. Estimated K values were found to be unaffected by the presence of added NOM. The spatial consistency and lack of NOM effects on the intrinsic equilibrium constants for SO2−4 adsorption is convenient for nutrient and contaminant transport modeling at the field‐scale.
Downstream Changes in Free Carbon Dioxide in an Upland Catchment from Northeastern Scotland
Authors: Dawson J. J. C. , Hope D. , Cresser M. S. , Billett M. F. 
Published: July 2010

AbstractSignificant losses of free carbon dioxide (CO2) to the atmosphere are likely to occur when soil‐water, supersaturated with free CO2, enters streams and equilibrates with atmospheric CO2. Spatial changes in dissolved free CO2 downstream from the river source should therefore demonstrate progressive equilibration with atmospheric CO2.Data on the spatial and diurnal variation in the concentration of dissolved free CO2 are described for a small headwater stream draining an acidic heather [Calluna vulgaris (L.) Hull] moorland catchment in northeastern Scotland. The degree to which free CO2 exceeded the concentration expected for atmospheric equilibration decreased rapidly downstream, from an excess partial pressure (epCO2) of >10 at the source of the stream to ca. 1.5 over a distance of 2 km downstream, suggesting that free CO2 was being lost from the water by outgassing as the water equilibrated with atmospheric CO2. Diurnal variation of ±1.0 CO2 units was also measured at the lowest point in the stream, with levels of CO2 being highest during the early morning and late evening (measurements were not taken during times of darkness) and lowest in the period from late morning to midafternoon. An estimate of the flux of C as free CO2 suggests that it comprises ca. 10% of the combined fluxes of dissolved organic carbon (DOC) and particulate organic carbon (POC). These results suggest that outgassing from and transport within river systems of soil‐derived CO2 forms an important component of the C flux from terrestrial ecosystems back to the atmosphere or to the ocean.
Dilution of Nonpoint‐Source Nitrate in Groundwater
Authors: Altman Susan J. , Parizek Richard R. 
Published: July 2010

AbstractNonpoint‐source pollution from agriculture can cause the degradation of groundwater and surface water. Some studies conducted in Coastal Plain aquifers have shown NO−3 removal from groundwater due to assimilation by vegetation or denitrification before discharge to a stream is significant; relatively few have been conducted on other physiographic and geological regions within the Chesapeake Bay watershed. This study was conducted at the boundary of the Valley and Ridge and Appalachian Plateau physiographic provinces to understand how the hydrological and geochemical conditions in this region effect the transport and removal of NO−3. The groundwater flow system at the farm studied, located at the base of a valley, is influenced by one groundwater flow component parallel to the axis of the valley and a second flowing perpendicular to the axis having been recharged from topographic highs along the sides of the valley. The axis‐perpendicular component is transporting NO−3 and Cl− applied as fertilizers and manure on an upgradient field and also Cl− from salting of an adjacent road to the study site. The relatively nutrient‐free water from the axis‐parallel component dilutes NO−3 and Cl− concentrations at the site from seasonal averages of 11 mg N/L and 90 mg Cl/L to levels <0.4 mg N/L and 1 mg Cl/L, respectively. Some evidence exists for NO−3 removal from groundwater <3 m belowground; however, it is difficult to confirm the removal process with dilution dominating the system.
Aerodynamic Measurements of Methyl Bromide Volatilization from Tarped and Nontarped Fields
Authors: Majewski Michael S. , McChesney Michael M. , Woodrow James E. , Prueger John H. , Seiber James N. 
Published: July 2010

AbstractMethyl bromide (MeBr) is used extensively in agriculture as a soil fumigant and there is growing concern over the role it may play in the depletion of stratospheric ozone. Methyl bromide is applied using various techniques and very little is known about how much of the applied fumigant volatilizes into the atmosphere after the application. This field study was designed to estimate the post‐application methyl bromide volatilization loss rates from two different application practices. The fields were approximately 6 km apart in Monterey County, California, and were treated in conformity with local practices as of 1992. The MeBr was injected at a depth of 25 to 30 cm. One field was covered simultaneously with a high‐barrier plastic film tarp during the application, and the other was left uncovered, but the furrows made by the injection shanks were bedded over. Volatilization fluxes were estimated using an aerodynamic‐gradient technique immediately following the completion of the application process and continued for 9 d for the tarped field and 6 d for the nontarped field. The cumulative volatilization losses from the tarped field were 22% of the nominal application within the first 5 d of the experiment and about 32% of the nominal application within 9 d including the one day after the tarp was removed on Day 8 after application. In contrast, the nontarped field lost 89% of the nominal application by volatilization in 5 d. The volatilization rate from the tarped field was shown to be significantly lower than the nontarped field at a 95% confidence level.
Critical Evaluation of Models and Their Parameters
Authors: Addiscott Tom , Smith Jo , Bradbury Nicky 
Published: July 2010

AbstractSome form of critical evaluatory procedure for models is needed to maintain the integrity of modeling and to ensure that the increasingly widespread use of models does not result in the propagation of misleading information. The term validation must be used with the clear understanding that no model can be validated in the sense that it has been unequivocally justified. All that can be achieved is to show how small the probability is that the model has been refuted. Whether this probability is acceptable is a subjective decision. The type of statistical test that is appropriate depends on the quality of the data against which the model is tested. Using a procedure that compares the sums of squares that result from the model not fitting the data with the sums of squares due to error in the data, gives a stringent test, but it requires the replication of measurements. Rigor is as important in evaluating parameters as it is in testing models. Direct measurement is the best option, but where a parameter has to be obtained by fitting, the statistical procedures used for validation are appropriate. In general, the further the data used for parameterization are removed from the data to be simulated the better. Problems can arise in both parameterization and validation if the model is nonlinear regarding its parameters, and the latter have appreciable variances. Parameterization and validation become more difficult as the complexity of the model or the scale at which it is used increase.
Methyl and Total Mercury in Boreal Wetland Plants, Experimental Lakes Area, Northwestern Ontario
Authors: Moore T. R. , Bubier J. L. , Heyes A. , Flett R. J. 
Published: July 2010

AbstractA review of Hg concentrations cited in the literature reveals values in the general sequence: grassland herbs < trees and shrubs < aquatic macrophytes < Sphagnum < mosses < lichens < fungi, excluding those samples collected near point sources of environmental Hg. Samples of vegetation collected from wetland and upland catchments in the Experimental Lakes Area contained from 4 to 160 μg total Hg (THg) kg−1 and 0.1 to 139 μg methyl Hg (MeHg) kg−1. The lowest concentrations of both THg and MeHg were found in the leaves and needles of trees and shrubs, and the highest concentrations occurred in bryophytes, both feather mosses and Sphagnum. Analysis of sections of the mosses revealed larger concentrations of MeHg in the upper live section, whereas THg concentrations increased slightly down the stem into the dead portions. In terms of broad ecological grouping, THg and MeHg concentrations increased the closer the plant's habitat to the water table, though certain upland mosses also contained very large THg and MeHg concentrations. When combined with biomass data, the vegetation of an ombrotrophic wetland contained an average of 30 μg THg m−2 and 0.4 μg MeHg m−2, dominantly (45 and 73%, respectively) in the mosses. These values are similar to that contained in the peat porewater, but small compared to the estimate of the stock of THg and MeHg contained in the 1.7 m thick peat (12 000 and 200 μg m−2, respectively).
The Cadmium Content of British Wheat Grain
Authors: Chaudri A. M. , Zhao F. J. , McGrath S. P. , Crosland A. R. 
Published: July 2010

AbstractThe Cd content of wheat (Triticum aestivum L.) grain samples collected representatively from the major wheat growing regions of Britain in 1982, 1992, and 1993 was measured. Geographical distributions of grain Cd content were compared with the total Cd concentration in soils of England and Wales. The ranges and mean grain Cd concentrations for 1982, 1992, and 1993 were (mg kg−1 dry weight, DW) 0.016 to 0.18, mean 0.052; 0.008 to 0.27, mean 0.042; and 0.004 to 0.31, mean 0.038, respectively. There was about a 20% decrease in mean grain Cd concentration from 1982 to 1992–1993. The proportion of samples above the World Health Organization's (WHO) limit of 0.12 mg Cd kg−1 DW was 4% for 1982 and 1992 and 2% for 1993. The geographical distribution of these high Cd grain samples corresponded with areas where the total soil Cd concentrations were significantly above background concentrations. Differences between wheat varieties were small and significant (P < 0.001) only for 1992. The concentration of Cd in white flour was significantly correlated with that in wholemeal flour (r = 0.95), and bran Cd was significantly correlated with white flour Cd (r = 0.87). On average, the concentration of Cd in bran was twice that in wholemeal flour, and white flour contained about 31% less Cd than wholemeal flour. The estimated daily dietary Cd intake in the United Kingdom (UK) through the consumption of wheat‐based products was about 8 μg Cd per person or about 11% of the WHO's limit of 70 μg Cd d−1. The Cd content of the vast majority of British wheat grain would not constitute a health hazard to the population of the UK or elsewhere.
Evaluation of Techniques to Improve White Pine Establishment on an Appalachian Minesoil
Authors: Torbert John L. , Burger James A. , Probert Timothy 
Published: July 2010

AbstractSeveral reclamation‐reforestation techniques were studied on a reclaimed surface mine in southern West Virginia to develop practical guidelines for the establishment of eastern white pine (Pinus strobus L.) forests interplanted with black locust (Robinia psuedoacacia L.). The study was designed to investigate (i) two herbaceous ground cover mixes (a conventional erosion control cover and a tree‐compatible reforestation cover); (ii) the effectiveness of establishing white pine and black locust by direct seeding versus hand‐planting; and (iii) the effect of fertilizing white pine with a fertilizer tablet. The study was established on a 40% slope with a minesoil derived primarily from an acidic (pH 4.8), oxidized sandstone. With an experimental variance from the West Virginia Department of Environmental Protection, final surface grading was minimized to avoid compaction. The reforestation ground cover was sparser than the conventional cover during the first year and denser after 5 yr, but the difference was not statistically significant and did not affect tree establishment. Although some white pines were established by direct seeding (2 kg/ha), their distribution was irregular. Black locusts were readily established by direct seeding (0.5 kg/ha), but the number of trees established was excessive and interfered with the growth of planted pine. Overall, growth of planted pine was very good, and fertilizer tablets did not result in significantly larger pines after 5 yr. Based on results from this study, the most practical way to establish a productive white pine‐black locust plantation is to plant pine seedlings and interplant or spot‐seed locusts between pines.