The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Dan Berggren Kleja - One of the best experts on this subject based on the ideXlab platform.
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Improved geochemical modeling of Lead Solubility in contaminated soils by considering colloidal fractions and solid phase EXAFS speciation
Applied Geochemistry, 2018Co-Authors: Carin Sjöstedt, Åsa Löv, Z Olivecrona, Kristin Boye, Dan Berggren KlejaAbstract:Abstract Lead (Pb) is a common contaminant in soils at e.g. mining, shooting range, and glassworks sites. In order to make reliable risk assessments and appropriate decisions on various “gentle remediation options”, such as applying phosphate, compost, or zero-valent iron to soils, the binding mechanism of Pb and its speciation needs to be known. Multi-surface geochemical equilibrium models are useful tools for estimating trace metal Solubility and speciation, but for Pb the predictions are often poor. This study evaluates the recent parameterization for Pb in the Visual MINTEQ code for its ability to predict the Solubility of Pb at different pH values in four historically contaminated Swedish soils. As an independent validation of the model performance, the modeled solid-phase speciation was compared to measured Pb speciation retrieved using extended X-ray absorption fine structure (EXAFS) spectroscopy. Furthermore, potential artefacts by the presence of Pb colloids were investigated by filtering solutions through both 0.45 μm and 10 kDa filters. The model accuracy for predicting Pb Solubility was improved compared with previous studies producing log root mean square error (RMSE) values below 0.42 in three out of four soils, just by using generic assumptions. The use of ultrafiltered (
Leo M. Condron - One of the best experts on this subject based on the ideXlab platform.
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Control of Lead Solubility in soil contaminated with Lead shot: effect of soil moisture and temperature
Soil Research, 2009Co-Authors: Ronald G. Mclaren, Corinne P. Rooney, Leo M. CondronAbstract:An incubation experiment was carried out to assess the rate of oxidation of Lead (Pb) shot and subsequent transfer of Pb to the soil under different soil moisture and temperature regimes. Lead was readily released from Pb shot into the soil environment due to rapid corrosion of the Pb shot; however, the rate of Pb shot dissolution was slower at 70% than at 100% field moisture capacity. The corrosion and development of crust material on Pb shot, and corresponding increases in soil solution Pb and Pb associated with the soil solid phase, were also slower at 10°C than 25 or 30°C. Soil moisture and temperature also influenced the speciation of soil solution Pb as modelled using WHAM 6, mainly through the effects of moisture and temperature on soil pH, total soluble Pb, and dissolved organic C. The rate of approach to equilibrium of the Pb shot–soil–soil solution system will be much slower where soil moisture and temperature limit Pb shot corrosion. Calculated free ion Pb2+ concentrations suggest that after 6 months, almost all samples contaminated with Pb shot exceeded soil critical limits for Pb toxicity.
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control of Lead Solubility in soil contaminated with Lead shot effect of soil ph
Environmental Pollution, 2007Co-Authors: Corinne P. Rooney, Ronald G. Mclaren, Leo M. CondronAbstract:An incubation experiment was carried out to assess the rate of oxidation of Pb shot and subsequent transfer of Pb to the soil under a range of soil pH conditions. Lead shot corrosion was rapid, so that soil solution and fine earth (<1mm) Pb concentrations increased rapidly within a few months. Corrosion products, dominated by hydrocerussite (Pb(3)(CO(3))(2)(OH)(2)), developed in crusts surrounding individual Pb pellets. However, irrespective of pH, Pb(2+) activities in the soil solutions, modelled using WHAM 6, were much lower than would be the case if they were controlled by the Solubility of the dominant Pb compounds present in the Pb shot crust material. In contrast, modelling of soil solid-solution phase distribution of Pb, again using WHAM 6, suggested that, at least during the 24 months of the study, soil solution Pb concentrations were more likely to be controlled by sorption of Pb by the soil solid phase.
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Control of Lead Solubility in soil contaminated with Lead shot: effect of soil pH.
Environmental pollution (Barking Essex : 1987), 2007Co-Authors: Corinne P. Rooney, Ronald G. Mclaren, Leo M. CondronAbstract:An incubation experiment was carried out to assess the rate of oxidation of Pb shot and subsequent transfer of Pb to the soil under a range of soil pH conditions. Lead shot corrosion was rapid, so that soil solution and fine earth (
Scott D Young - One of the best experts on this subject based on the ideXlab platform.
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predicting trace metal Solubility and fractionation in urban soils from isotopic exchangeability
Environmental Pollution, 2017Co-Authors: Scott D Young, E H BaileyAbstract:Metal-salt amended soils (MA, n = 23), and historically-contaminated urban soils from two English cities (Urban, n = 50), were investigated to assess the effects of soil properties and contaminant source on metal lability and Solubility. A stable isotope dilution method, with and without a resin purification step, was used to measure the lability of Cd, Cu, Ni, Pb and Zn. For all five metals in MA soils, lability (%E-values) could be reasonably well predicted from soil pH value with a simple logistic equation. However, there was evidence of continuing time-dependent fixation of Cd and Zn in the MA soils, following more than a decade of storage under air-dried conditions, mainly in high pH soils. All five metals in MA soils remained much more labile than in Urban soils, strongly indicating an effect of contaminant source on metal lability in the latter. Metal Solubility was predicted for both sets of soil by the geochemical speciation model WHAM-VII, using E-values as an input variable. For soils with low metal solution concentrations, over-estimation of Cd, Ni and Zn Solubility was associated with binding to the Fe oxide fraction while accurate prediction of Cu Solubility was dependent on humic acid content. Lead Solubility was most poorly described, especially in the Urban soils. Generally, slightly poorer estimation of metal Solubility was observed in Urban soils, possibly due to a greater incidence of high pH values. The use of isotopically exchangeable metal to predict Solubility is appropriate both for historically contaminated soils and where amendment with soluble forms of metal is used, as in toxicological trials. However, the major limitation to predicting Solubility may lie with the accuracy of model input variables such as humic acid and Fe oxide contents where there is often a reliance on relatively crude analytical estimations of these variables.
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predicting the Solubility and lability of zn cd and pb in soils from a minespoil contaminated catchment by stable isotopic exchange
Geochimica et Cosmochimica Acta, 2013Co-Authors: Simon Chenery, Ezzat R Marzouk, Scott D YoungAbstract:The Rookhope catchment of Weardale, England, has a diverse legacy of contaminated soils due to extensive Lead mining activity over four centuries. We measured the isotopically exchangeable content of Pb, Cd and Zn (E-values) in a large representative subset of the catchment soils (n = 246) using stable isotope dilution. All three metals displayed a wide range of %E-values (c. 1–100%) but relative lability followed the sequence Cd > Pb > Zn. A refinement of the stable isotope dilution approach also enabled detection of non-reactive metal contained within suspended sub-micron (<0.22 μm) colloidal particles (SCP-metal). For most soils, the presence of non-labile SCP-metal caused only minor over-estimation of E-values (<2%) but the effect was greater for soils with particularly large humus or carbonate contents. Approximately 80%, 53% and 66% of the variability in Zn, Cd and Pb %E-values (respectively) could be explained by pH, loss on ignition and total metal content. E-values were affected by the presence of ore minerals at high metal contents Leading to an inconsistent trend in the relationship between %E-value and soil metal concentration. Metal Solubility, in the soil suspensions used to measure E-values, was predicted using the WHAM geochemical speciation model (versions VI and VII). The use of total and isotopically exchangeable metal as alternative input variables was compared; the latter provided significantly better predictions of Solubility, especially in the case of Zn. Lead Solubility was less well predicted by either version of WHAM, with over-prediction at low pH and under-prediction at high soil pH values.
Carin Sjöstedt - One of the best experts on this subject based on the ideXlab platform.
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Improved geochemical modeling of Lead Solubility in contaminated soils by considering colloidal fractions and solid phase EXAFS speciation
Applied Geochemistry, 2018Co-Authors: Carin Sjöstedt, Åsa Löv, Z Olivecrona, Kristin Boye, Dan Berggren KlejaAbstract:Abstract Lead (Pb) is a common contaminant in soils at e.g. mining, shooting range, and glassworks sites. In order to make reliable risk assessments and appropriate decisions on various “gentle remediation options”, such as applying phosphate, compost, or zero-valent iron to soils, the binding mechanism of Pb and its speciation needs to be known. Multi-surface geochemical equilibrium models are useful tools for estimating trace metal Solubility and speciation, but for Pb the predictions are often poor. This study evaluates the recent parameterization for Pb in the Visual MINTEQ code for its ability to predict the Solubility of Pb at different pH values in four historically contaminated Swedish soils. As an independent validation of the model performance, the modeled solid-phase speciation was compared to measured Pb speciation retrieved using extended X-ray absorption fine structure (EXAFS) spectroscopy. Furthermore, potential artefacts by the presence of Pb colloids were investigated by filtering solutions through both 0.45 μm and 10 kDa filters. The model accuracy for predicting Pb Solubility was improved compared with previous studies producing log root mean square error (RMSE) values below 0.42 in three out of four soils, just by using generic assumptions. The use of ultrafiltered (
Hubert Bril - One of the best experts on this subject based on the ideXlab platform.
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minerals controlling arsenic and Lead Solubility in an abandoned gold mine tailings
Science of The Total Environment, 2000Co-Authors: Christophe Roussel, Catherine Neel, Hubert BrilAbstract:Numerous areas have been contaminated by heavy metals and metalloids due to industrial and mining activities. Studies investigating the behavior of such contaminants in the environment have identified speciation as a key factor controlling their mobility, availability and toxicity. Here we characterize As- and Pb-bearing phases resulting from the oxidation of sulfide-rich tailings of a former gold mine (La Petite Faye, France) in order to assess the risk for water quality. Elements were first pre-concentrated by granulometric fractionation (sedimentation in deionized water) and then investigated using X-ray diffraction and electron microprobe analyses. Two main As-Pb-bearing minerals were clearly identified: scorodite (FeAsO4 x 2H2O) and beudantite PbFe3(AsO4)(SO4)(OH)6. Minor amounts of As and Pb were dissolved in deionized water during granulometric fractionation, indicating the possible presence of other soluble Pb-sulfates which could be some of the primary metastable products of sulfide oxidation. This dissolution also provides information about the fate of these phases in the case of intensive leaching of the tailings. Scorodite may not be considered as a relevant candidate for As on-site immobilization, because its Solubility largely exceeds drinking water standards whatever the pH. Since beudantite Solubility has not yet been determined, an estimation of its Solubility product was obtained using the Gibbs free energy of formation of plumbojarosite [Pb0.5Fe3(SO4)2(OH)6]. This estimation suggests that beudantite should efficiently maintain low Pb concentration in waters. However, Pb dissolution in deionized water during the granulometric fractionation led to Pb concentrations much higher than the French and US drinking water standards (2.4 x 10(-7) mol l(-1)), which may be due to dissolution of the suspected metastable Pb-sulfates. Accurate determination of beudantite Solubility is now required to improve the Pb risk assessment on such polluted sites.