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C Picot - One of the best experts on this subject based on the ideXlab platform.

  • short term transformations of Lead and cadmium Compounds in soil after contamination
    European Journal of Soil Science, 2003
    Co-Authors: P Bataillard, P Cambier, C Picot
    Abstract:

    The behaviour and fate of trace metals, in particular Lead and cadmium, when they contaminate the soil as atmospheric fall-out are not well understood. To improve our understanding, we incorporated pure Compounds of Lead and cadmium into samples taken from surface horizons of three chemically contrasting soils and monitored the changes in their speciation by analysing the soil solution. In most instances the concentrations of trace metals in solution were maximal during the first few days after mixing the contaminants with the soil, and depended strongly on soil type. The exception was when the contaminant was added as sulphide particles. The initial speciation of metals also influenced their solubility, following a decreasing order which did not depend on the soil type: for Lead: oxide = carbonate > sulphate > sulphide, and for cadmium: sulphate > oxide > carbonate > sulphide. Lead sulphide was progressively oxidized, but cadmium sulphide was hardly dissolved. When Lead was added as sulphate, between 10 and 20% of Lead particles dissolved, regardless of the soil type. For the other species, dissolution was enhanced at lower soil pH. Thermodynamic calculations with the WinHumic V program indicated that the solution was not saturated with respect to Lead sulphate. We conclude that dissolution must be limited by the adsorption of inhibitors on reactive surfaces. The calculations also showed that precipitation of chloropyromorphite probably controls Lead concentration in leachate from the acid organic soil. Finally, both soil type and initial speciation of contaminants control the behaviour of trace metals in soils for a time greater than a cropping season and must be considered for understanding their environmental impact.

P Bataillard - One of the best experts on this subject based on the ideXlab platform.

  • short term transformations of Lead and cadmium Compounds in soil after contamination
    European Journal of Soil Science, 2003
    Co-Authors: P Bataillard, P Cambier, C Picot
    Abstract:

    The behaviour and fate of trace metals, in particular Lead and cadmium, when they contaminate the soil as atmospheric fall-out are not well understood. To improve our understanding, we incorporated pure Compounds of Lead and cadmium into samples taken from surface horizons of three chemically contrasting soils and monitored the changes in their speciation by analysing the soil solution. In most instances the concentrations of trace metals in solution were maximal during the first few days after mixing the contaminants with the soil, and depended strongly on soil type. The exception was when the contaminant was added as sulphide particles. The initial speciation of metals also influenced their solubility, following a decreasing order which did not depend on the soil type: for Lead: oxide = carbonate > sulphate > sulphide, and for cadmium: sulphate > oxide > carbonate > sulphide. Lead sulphide was progressively oxidized, but cadmium sulphide was hardly dissolved. When Lead was added as sulphate, between 10 and 20% of Lead particles dissolved, regardless of the soil type. For the other species, dissolution was enhanced at lower soil pH. Thermodynamic calculations with the WinHumic V program indicated that the solution was not saturated with respect to Lead sulphate. We conclude that dissolution must be limited by the adsorption of inhibitors on reactive surfaces. The calculations also showed that precipitation of chloropyromorphite probably controls Lead concentration in leachate from the acid organic soil. Finally, both soil type and initial speciation of contaminants control the behaviour of trace metals in soils for a time greater than a cropping season and must be considered for understanding their environmental impact.

P Cambier - One of the best experts on this subject based on the ideXlab platform.

  • short term transformations of Lead and cadmium Compounds in soil after contamination
    European Journal of Soil Science, 2003
    Co-Authors: P Bataillard, P Cambier, C Picot
    Abstract:

    The behaviour and fate of trace metals, in particular Lead and cadmium, when they contaminate the soil as atmospheric fall-out are not well understood. To improve our understanding, we incorporated pure Compounds of Lead and cadmium into samples taken from surface horizons of three chemically contrasting soils and monitored the changes in their speciation by analysing the soil solution. In most instances the concentrations of trace metals in solution were maximal during the first few days after mixing the contaminants with the soil, and depended strongly on soil type. The exception was when the contaminant was added as sulphide particles. The initial speciation of metals also influenced their solubility, following a decreasing order which did not depend on the soil type: for Lead: oxide = carbonate > sulphate > sulphide, and for cadmium: sulphate > oxide > carbonate > sulphide. Lead sulphide was progressively oxidized, but cadmium sulphide was hardly dissolved. When Lead was added as sulphate, between 10 and 20% of Lead particles dissolved, regardless of the soil type. For the other species, dissolution was enhanced at lower soil pH. Thermodynamic calculations with the WinHumic V program indicated that the solution was not saturated with respect to Lead sulphate. We conclude that dissolution must be limited by the adsorption of inhibitors on reactive surfaces. The calculations also showed that precipitation of chloropyromorphite probably controls Lead concentration in leachate from the acid organic soil. Finally, both soil type and initial speciation of contaminants control the behaviour of trace metals in soils for a time greater than a cropping season and must be considered for understanding their environmental impact.

J C Yang - One of the best experts on this subject based on the ideXlab platform.

  • effects of soil amendments on Lead uptake by two vegetable crops from a Lead contaminated soil from anhui china
    Environment International, 2004
    Co-Authors: Yongguan Zhu, Shuqin Chen, J C Yang
    Abstract:

    Previous studies have documented that phosphate Compounds of Lead (Pb) [e.g., pyromorphite Pb5(PO4)3-(X), where X=OH, F or Cl] are comparatively insoluble, and their formation in Pb-contaminated soil may be a means of reducing the bioavailability and chemical lability of Pb in soil. In this study, the effect of phosphate compound amendments on the bioavailability of Pb in a polluted alkaline soil was examined. A Pb-contaminated soil was treated with hydroxyapatite (HA), phosphate rock (PR), water-soluble P fertilizer (single superphosphate, SSP) and the combination of HA with SSP. The bioavailability of Pb was determined in plant uptake studies with vegetables (Brassica campetris L. var. communis, BC) and Brassica oleracea L. var. acephala, BO) and sequential extraction. The results indicated that the Pb concentrations in both shoots and roots of two vegetable plants decreased with increasing quantities of added P compound, and the HA treatment had the best effect at the level of 5000 mg of P kg(-1)as compared with other treatments in which the Pb concentrations in shoots of BO and BC decreased 51.9% and 65.5%, respectively, and the Pb concentrations in roots of BO and BC decreased 67.3% and 57.2%, respectively, as compared with the control treatment. The SSP treatment had little effect on the Pb concentrations in plant tissues. Sequential extraction results indicated that the addition of soil amendments transform soil Pb from nonresidual fractions to residual fraction substantially. The effect of treatments followed this order at the equivalent P addition: HA>PR>HA+SSP>SSP. The results suggested that HA amendments can lower the bioavailability and increase the geochemical stability of soil Pb, so it has the potential for in situ remediation in Pb-contaminated soils.

Yongguan Zhu - One of the best experts on this subject based on the ideXlab platform.

  • effects of soil amendments on Lead uptake by two vegetable crops from a Lead contaminated soil from anhui china
    Environment International, 2004
    Co-Authors: Yongguan Zhu, Shuqin Chen, J C Yang
    Abstract:

    Previous studies have documented that phosphate Compounds of Lead (Pb) [e.g., pyromorphite Pb5(PO4)3-(X), where X=OH, F or Cl] are comparatively insoluble, and their formation in Pb-contaminated soil may be a means of reducing the bioavailability and chemical lability of Pb in soil. In this study, the effect of phosphate compound amendments on the bioavailability of Pb in a polluted alkaline soil was examined. A Pb-contaminated soil was treated with hydroxyapatite (HA), phosphate rock (PR), water-soluble P fertilizer (single superphosphate, SSP) and the combination of HA with SSP. The bioavailability of Pb was determined in plant uptake studies with vegetables (Brassica campetris L. var. communis, BC) and Brassica oleracea L. var. acephala, BO) and sequential extraction. The results indicated that the Pb concentrations in both shoots and roots of two vegetable plants decreased with increasing quantities of added P compound, and the HA treatment had the best effect at the level of 5000 mg of P kg(-1)as compared with other treatments in which the Pb concentrations in shoots of BO and BC decreased 51.9% and 65.5%, respectively, and the Pb concentrations in roots of BO and BC decreased 67.3% and 57.2%, respectively, as compared with the control treatment. The SSP treatment had little effect on the Pb concentrations in plant tissues. Sequential extraction results indicated that the addition of soil amendments transform soil Pb from nonresidual fractions to residual fraction substantially. The effect of treatments followed this order at the equivalent P addition: HA>PR>HA+SSP>SSP. The results suggested that HA amendments can lower the bioavailability and increase the geochemical stability of soil Pb, so it has the potential for in situ remediation in Pb-contaminated soils.