bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Nonelectrostatic Surface Complexation Model for Lead Sorption on Soils and Mineral Surfaces
Authors: Van Benschoten John E. , Young William H. , Matsumoto Mark R. , Reed Brian E. 
Published: July 2010

AbstractA nonelectrostatic surface complexation model is applied to three data sets of increasing complexity: synthetic data for Pb adsorption to hydrous ferric oxide (HFO); data from the literature involving Pb adsorption to three mineral surfaces (goethite, alumina, and silica); and data for Pb adsorption on a field soil. The model is intended for engineering applications (e.g., soil remediation) rather than to provide a comprehensive description of sorption phenomena. The model is simple enough that it can be implemented on a standard spreadsheet and in its simplest form requires only two fitting parameters. Proton stoichiometry for the surface reactions is determined using Kurbatov plots; total site density (ST) and surface‐binding constant (Kpb) are fit to experimental sorpfion data. Complexation reactions between Pb and major ligands are included in the model. Although similar models have been presented previously by other researchers, dissolved solute speciation often was ignored and applications focused on trace metal adsorption and not on soil contamination and remediation. Model applications to Pb sorption data for mineral surfaces have shown excellent correlation with experimental data (r2 values from 0.95 to 0.99, SE of 3–7%). For an environmental soil, r2 values f rom 0.82 t o 0.96 and std errors from 4 to 8% were observed. The model simulates effects of solution chemistry on sorption nearly as well as traditional surface complexation models, but with fewer fitting parameters. Interpretation of fitted parameters and guidelines for model use are discussed.
Mercury Concentrations in Soils Adjacent to a Former Chlor‐Alkali Plant
Authors: Rule J. H. , Iwashchenko M. S. 
Published: July 2010

AbstractThe mean soil mercury (Hg) concentration (1.060 mg−1) for samples collected within 2 km of a former chlor‐alkali plant (National Priority List 418) in Saltville, VA, was determined to be approximately 17 times higher than regional background soil samples (0.063 mg kg−1). Anomalous values as defined by the mean of the regional background plus three standard deviations were found at all but one of 28 sampling sites within a 2‐km radius from the former chlor‐alkali plant. Soil organic C, topographic factors, wind patterns, and elevation were variables significantly related to Hg concentration as determined by analysis of data by multiple regression. Soil Hg levels decreasing with distance from the former plant were indicative of a point source distribution pattern. A made land soil type (Udorthent), which appears to be a by‐product of the chlor‐alkali manufacturing process, was found proximal to the former plant site and contained about 68 times (4.310 mg kg−1) more Hg than the regional background concentration. The significant environmental Hg contamination is likely to remain in the Saltville ecosystem for a very long time due to continued emissions from waste ponds. The range of contamination, especially downwind of the plant site, most probably extends well beyond the bounds of the present study area.
Dissolution of Trapped Nonaqueous Phase Liquids in Sand Columns
Authors: Fortin J. , Jury W. A. , Anderson M. A. 
Published: July 2010

AbstractSoil column experiments were designed to evaluate the dissolution and leaching under continuous water flow of two immobilized nonaqueous phase liquids (NAPL): o‐xylene, which is lighter than water (LNAPL) and o‐dichlorobenzene, which is denser than water (DNAPL). Major differences were observed in the mobility and dissolution of the LNAPL and the DNAPL under continuous leaching. Under water‐saturated conditions and downward flow, the trapped LNAPL was removed from sand columns by dissolution and by mobilization of small droplets. In contrast, the DNAPL remained trapped in the soil matrix during the leaching phase and was removed by dissolution only. The model used to describe the data assumes that the NAPL is trapped in the soil volume as ideal spheres of initial diameter d0. The transport parameters of the model were determined by a separate tracer experiment, so that the only parameter fitted to the resident residual NAPL and outflow observations was the initial diameter of the spheres. The sphere model described the data fairly well, with optimum initial sphere diameter of 0.12 cm for o‐dichlorobenzene and varying between 0.17 to 0.21 cm for o‐xylene. The optimum diameter of the spheres was used to calculate the length of the mass transfer zone (Lm) over which solution passing through the NAPL region changes from zero NAPL concentration to NAPL water solubility. Lm varied between 7.9 to 11.1 cm for o‐xylene, and from 3.7 cm in the finer sand to 5.2 cm in the coarser material for o‐dichlorobenzene.
Patchiness in Microbial Nitrogen Transformations in Groundwater in a Riparian Forest
Authors: Jacinthe Pierre‐Andre , Groffman Peter M. , Gold Arthur J. , Mosier Arvin 
Published: July 2010

AbstractWe measured microbial N transformations in 15 cm diam. by 40 cm intact horizontal sections of aquifer material (mesocosms), taken from a riparian forest in Rhode Island, USA, incubated under ambient conditions. The mesocosms allowed us to measure these transformations on the same scale as hydrologic tracer methods (Br−/NO−3 ratios) that measure net NO−3 removal. Our objective was to reconcile discrepancies between hydrologic tracer and microbial measurements in previous studies where laboratory‐based microbial NO−3 consumption measurements were much lower than in situ hydrologic measurements of net NO−3 removal. We hypothesized that small “patches” of organic matter in the aquifer matrix, which are easily missed when sampling for microbial measurements, are “hotspots” of NO−3 removal and are responsible for these discrepancies. Mesocosms were subjected to three treatments [Br− only, Br− + 15NO−3 Br− + 15NO−3 + dissolved organic carbon (DOC)]. Solution (NH+4, NO−3, dissolved organic N) and gaseous (N2O, 15N2O, and 15N2) inputs and outputs to the mesocosms were measured over a 132‐d incubation, followed by destructive sampling for the presence of patches and residual 15N in aquifer matrix and patch material. Total (gross) NO−3 consumption by denitrification and immobilization was greater than net removal of NO−3 measured by Br−/NO−3 ratios. Net NO−3 consumption was only observed in mesocosms that contained “patches” of organic matter and was not increased by addition of DOC, suggesting that these patches, which represent <1% of aquifer weight, are critical to groundwater NO−3 removal in riparian forests.
Phytoremediation of a Radiocesium‐Contaminated Soil: Evaluation of Cesium‐137 Bioaccumulation in the Shoots of Three Plant Species
Authors: Lasat Mitch M. , Fuhrmann Mark , Ebbs Stephen D. , Cornish Jay E. , Kochian Leon V. 
Published: July 2010

AbstractA field study was conducted to investigate the potential of three plant species for phytoremediation of a 137Cs‐contaminated site. Approximately 40‐fold more 137Cs was removed from the contaminated soil in shoots of red root pigweed (Amaranthus retroflexus L.) than in those of Indian mustard [Brassica juncea (L.) Czern] and tepary bean (Phaseolus acutifolius A. Gray). The greater potential for 137Cs removal from the soil by A. retroflexus was associated with both high concentration of 137Cs in shoots and high shoot biomass production. Approximately 3% of the total 137Cs was removed from the top 15 cm of the soil (which contained most of the soil radiocesium) in shoots of 3‐too‐old A. retroflexus plants. Soil leaching tests conducted with 0.1 and 0.5 M NH4NO3 solutions eluted as much as 15 and 19%, respectively, of the soil 137Cs. Addition of NH4NO3 to the soil, however, had no positive effect on 137Cs accumulation in shoots in any of the species investigated. It is proposed that either NH4NO3 solution quickly percolated through the soil before interacting at specific 137Cs binding sites or radiocesium mobilized by NH4NO3 application moved below the rhizosphere, becoming unavailable for root uptake. Further research is required to optimize the phytotransfer of the NH4NO3‐mobilized 137Cs. With two croppings of A. retroflexus per year and a sustained rate of extraction, phytoremediation of this 137Cs‐contaminated soil appears feasible in <15 yr.
Biosolids Effects on Tobosagrass and Alkali Sacaton in a Chihuahuan Desert Grassland
Authors: Benton Mark W. , Wester David B. 
Published: July 2010

AbstractEnvironmentally responsible use of anaerobically digested biosolids (municipal sewage sludge) is an increasingly urgent ecological and societal concern. There is relatively little information available on effects of biosolids in arid and semiarid rangelands. The purpose of this research was to evaluate effects of rate, season, and number of consecutive years of biosolids application on tobosagrass (Hilaria mutica) and alkali sacaton (Sporobolus airoides), two commonly occurring native grasses in the Chihuahuan desert grassland. Biosolids were topically applied at rates of 0, 7, 18, 34, or 90 Mg ha−1 either during the dormant season or just prior to the onset of the growing season for 1 yr only, or for 2, 3, or 4 consecutive years; one‐half of the experimental plots were provided supplemental irrigation. In general, biosolids increased plant length and aboveground standing crop of these species. Plants responded more to dormant season application than to growing season application in the first year of the study. Carry‐over effects from earlier applications on current year's growth were species‐specific and depended on growing conditions.
Soluble Organic Carbon and Carbon Dioxide Fluxes in Maize Fields Receiving Spring‐Applied Manure
Authors: Gregorich E. G. , Rochette P. , McGuire S. , Liang B. C. , Lessard R. 
Published: July 2010

AbstractMore than 19 million Mg of dairy manure are produced annually in the Canadian provinces of Quebec and Ontario, and most of it is spread on agricultural fields. Quantitative information on the impact of manure management practices on levels of soluble organic carbon (SOC) and emissions of CO2 is important for assessing whether this management significantly contributes to increasing atmospheric CO2 concentrations. The objective of this study was to measure the effects of dairy cattle manure (applied at 0, 56, and 112 Mg ha−1) on SOC levels in, and soil surface CO2 fluxes from, a typical maize (Zea mays L.) field in central Canada, from April to October. The higher rate of manure increased both the CO2 emissions and the SOC levels by a factor of two to three compared with the control. Fluxes of CO2 were very low immediately after thaw, increased sharply following manure application and increased again in mid‐June at the time when temperature and soil moisture increased; thereafter, fluxes declined throughout the rest of the season. Over the season, which was drier than normal, SOC was not a good predictor of CO2 flux. Carbon dioxide flux increased proportionately less for the second 56 Mg ha−1 increment of manure added than for the first increment. Factors other than the quantity of S OC limited soil respiration at the highest manure application rate. Carbon dioxide is contributed to the atmosphere at a lower rate, and proportionately more manure C is retained in soil with increasing levels of manure applied.
Hydrologic Controls on Phosphorus Loss from Upland Agricultural Watersheds
Authors: Gburek William J. , Sharpley Andrew N. 
Published: July 2010

AbstractDevelopment of strategies for controlling P loss from upland agricultural watersheds requires an ability to identify specific source areas of P at field and farm scales, and to predict their resultant effects at the watershed scale. Key to identification of P source areas is defining the interaction between P availability over the landscape and its potential for movement to the watershed outlet by runoff and erosion. A current weakness in quantifying this interaction is determining specific zones of runoff and erosion within a watershed, that is, source areas for the P transport mechanisms. Research results from a series of studies within a small, upland agricultural watershed in east‐central Pennsylvania show that the zones of runoff production, and consequently the areas ultimately controlling most P transport, are often a limited and identifiable portion of the landscape. Quantifying the hydrologic controls on P transport within and from a watershed in this way allows us to focus management options on small and definable portions of the total watershed that contribute most export.
Phosphorus Loss in Agricultural Drainage: Historical Perspective and Current Research
Authors: Sims J. T. , Simard R. R. , Joern B. C. 
Published: July 2010

AbstractThe importance of P originating from agricultural sources to the nonpoint source pollution of surface waters has been an environmental issue for decades because of the well‐known role of P in eutrophication. Most previous research and nonpoint source control efforts have emphasized P losses by surface erosion and runoff because of the relative immobility of P in soils. Consequently, P leaching and losses of P via subsurface runoff have rarely been considered important pathways for the movement of agricultural P to surface waters. However, there are situations where environmentally significant export of P in agricultural drainage has occurred (e.g., deep sandy soils, high organic matter soils, or soils with high soil P concentrations from long‐term overfertilization and/or excessive use of organic wastes). In this paper we review research on P leaching and export in subsurface runoff and present overviews of ongoing research in the Atlantic Coastal Plain of the USA (Delaware), the midwestem USA (Indiana), and eastern Canada (Quebec). Our objectives are to illustrate the importance of agricultural drainage to nonpoint source pollution of surface waters and to emphasize the need for soil and water conservation practices that can minimize P losses in subsurface runoff.
Reducing Phosphorus Losses from Surface‐Irrigated Fields: Emerging Polyacrylamide Technology
Authors: Lentz R. D. , Sojka R. E. , Robbins C. W. 
Published: July 2010

AbstractMost P losses from surface‐irrigated fields occur via runoff, are associated with eroded sediment, and can be minimized by eliminating irrigation‐induced erosion. A convenient new practice that eliminates furrow irrigation‐induced soil losses uses a high molecular weight, anionic polyacrylamide (PAM) applied to initial irrigation inflows. We hypothesized that, compared to control furrows, PAM treatment would reduce field losses of ortho P, total P, NO3, and lower tailwater chemical oxygen demand (COD). Two PAM treatments were tested: I10 applied 10 mg L−1 PAM only during the furrow advance (i.e., the application was halted after runoff began) and C1 applied 1 mg L−1 PAM continuously throughout the irrigation. Soil was Portneuf silt loam (coarse‐silty, mixed, mesic Durixerollic Calciorthid) with 1.6% slope. Initial inflows were cut back from 23 to 15 L min−1 after 1.5 to 6 h. Total soil loss over four irrigations was 3.06 Mg ha−1 for control furrows vs. 0.33 (C1) and 0.24 (I10) for PAM‐treated furrows. Ortho‐P and total P concentrations in control tailwaters were five to seven times that of PAM treatments, and COD levels were four times those of PAM treatments. Runoff in controls was two times that of PAM‐treated furrows. PAM‐I10 lowered furrow stream nutrient concentrations more than did PAM‐C1, but owing to disparities in runoff, the two treatments produced similar cumulative sediment and nutrient mass losses. The PAM is effective, convenient, and economical, and greatly reduces P and organic material (COD) losses from surface‐irrigated fields.
A Laboratory Evaluation of Trace Element Mobility from Flooding and Nutrient Loading of Coeur d'Alene River Sediments
Authors: La Force M. J. , Fendorf S. E. , Li G. C. , Schneider G. M. , Rosenzweig R. F. 
Published: July 2010

AbstractThe main stem (MSCDR) and south fork (SFCDR) of the Coeur d'Alene River, Idaho, are contaminated with heavy metals from many years of mining. To assess the potential impacts of flooding on water quality in the river system, contaminants in undisturbed sediments were subjected to selective extraction, and their rates of release measured in simulated laboratory flooding experiments. To simulate flooding, 18 columns were constructed allowing the sediment‐water interface to be monitored for pH, Eh, and dissolved concentrations of As, Fe, Mn, Pb, and Zn. These columns were subjected to four types of treatments. The first two involved overlaying the columns with N2(g)‐ or air‐purged river water, whereas the latter two involved overlaying sediment columns with N2(g)‐ or air‐purged river water amended with C and N. Treatment with unamended river water resulted in the immediate release of Zn at an average concentration of 10.4 mg L−1 from sediment taken along the MSCDR at Cataldo, ID. Treatment with either oxic or anoxic river water amended with glucose and N resulted in an order of magnitude increase in sediment microbial density. These biotic changes correlated with fivefold to 100‐fold increases in the release of trace elements into the aqueous phase. Our results suggest that heavy metal loading of waters in the Coeur d'Alene system occurs not only as a result of the resuspension of particulate matter, but also as a result of transformations that are either directly or indirectly mediated by sediment microbiota. Undisturbed sediments currently situated in the riverbanks of the MSCDR and SFCDR have the capacity to release contaminants into the river system during flooding. This release could be dramatically enhanced by increased nutrient levels into the CDA river system.
Bioavailability of Copper and Zinc in Soils Treated with Alkaline Stabilized Sewage Sludges
Authors: Luo Y. M. , Christie P. 
Published: July 2010

AbstractA glasshouse experiment was conducted to determine the bioavailability of Cu and Zn in a sandy loam and a clay loam. Spring barley (Hordeum vulgare L. cv. Forrester) was grown for 40 d in the two soils following application of alkaline‐stabilized sewage sludge. The soils were mixed with sludge product to give mixtures equivalent to fresh sludge cake application rates of 30, 90, and 120 Mg/ha. Unamended controls and all sludge‐treated soils except those receiving 90 Mg/ha were sequentially extracted to fractionate Cu and Zn into five operationally defined chemical forms. About 74% of total Cu and 80% of total Zn remained in the RESD fraction of the sludge‐amended soils. The largest extractable Cu fraction was OM‐Cu while the largest extractable Zn fraction was FeMnOX‐Zn in both types of sludge product and in both soils. The EXCH and CARB fractions together comprised <2% of total Cu and Zn in sludge‐amended soils. The sludge product raised soil pH and, except for EXCH‐Zn, increased the concentrations of both metals in the four extractable soil fractions. The sludge product increased barley shoot uptake of Cu by 112% and of Zn by 67% on average. However, sludge application decreased the shoot Zn concentration by 39% in the clay loam. This may be due to a decrease in EXCH‐Zn in the soil together with a dilution effect in the shoots resulting from a positive yield response to the sludge cake. Plant metal uptake was correlated (P < 0.05) with the various soil fractions, particularly EXCH‐Cu and CARB‐Zn.
A Comparison of Three Kriging Methods Using Auxiliary Variables in Heavy‐Metal Contaminated Soils
Authors: Juang Kai‐Wei , Lee Dar‐Yuan 
Published: July 2010

AbstractCharacterization of the spatial distribution of pollutants in contaminated soils is important for risk assessment and soil reclamation. In this study, three kriging methods using auxiliary variables, cokriging, kriging combined with regression, and kriging combined with Q‐mode factor analysis, were used for interpolation of heavy metal concentrations in a contaminated site. The three interpolation methods were evaluated for whether or not they could make better use of an auxiliary variable for estimation of the spatial distribution of heavy metals. A heavy metal contaminated site about 10 ha in area, situated in Taoyuan, Taiwan, was studied. The results demonstrate that better use of the auxiliary variable in interpolations of the target variable was made using kriging combined with regression compared to using cokriging or kriging combined with Q‐mode factor analysis. The results also show that the spatial distribution patterns of the target variables estimated using kriging combined with Q‐mode factor analysis were more similar to those estimated using kriging combined with regression than were those estimated using cokriging. In addition, kriging combined with regression and kriging combined with Q‐mode factor analysis could avoid negative estimates, which occur in cokriging. Moreover, both of them were more robust than cokriging. Simultaneous estimation of spatial distributions of several target variables using an auxiliary variable was demonstrated for the kriging combined with Q‐mode factor analysis procedure. However, for only one target variable, kriging combined with regression was simpler and less cumbersome than cokriging.
Effects of Carbon Dioxide and Nitrogen on Growth and Nitrogen Uptake in Ponderosa and Loblolly Pine
Authors: Johnson D. W. , Thomas R. B. , Griffin K. L. , Tissue D. T. , Ball J. T. , Strain B. R. , Walker R. F. 
Published: July 2010

AbstractThe purpose of this paper is to summarize the results of a series of greenhouse and open‐ top chamber studies on the effects of N and elevated atmospheric CO2 on ponderosa and loblolly pine (Pinus ponderosa Laws, and P. taeda L.) to evaluate common patterns of response. Growth response to elevated CO2 ranged from zero to more than 1000%, depending largely upon N status. In both species, growth response to CO2 was greater under moderate N deficiency than under extreme N deficiency or N sufficiency/excess. Elevated CO2 generally caused lowered tissue N concentrations in many (but not all) cases, which in turn resulted in smaller increases in N uptake than in biomass. Growth response to N ranged from −50 (in ponderosa pine) to more than 1000%, depending upon the N status of the control medium. Growth response to N was enhanced by elevated CO2 when N was in the extreme deficiency range but not when N was in the moderate deficiency range. In two separate studies, ponderosa pine responded negatively to high N inputs, and in each case this response was mitigated by elevated CO2. Collectively, these results show that (i) N deficiency is a continuum rather than a step function, (ii) responses to elevated CO2 vary across this continuum of N deficiency, and (iii) elevated CO2 greatly enhances growth response to N additions when N is initially in the extremely deficient range.