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Bioassay phytoavailability of Cd, Zn and Cu in soils unamended or long term biosolids amended fields with pH made equal, to characterize changes in the adsorption equilibria of the paired soils. Evaluate changes in Fe or Mn
oxides or humics which could cause observed changes in etal uptake. Collect soils from Pb-contaminated sites to evaluate the effect of phosphate and Tailor-Made Biosolids on bioavailability of different Pb sources or soils, and chemical species of Pb formed in treated soils.
Soils will be obtained from long-term field experiments with known additions of biosolids, but organic carbon equal to the controls. ARS will measure phytoavailability of Cd, Zn ,and Cu in biosolids amended and unamended soils, using growth chamber plant bioassay methods with equal pH for test soils. EPA will conduct adsorption studies to evaluate ability of the test soils to limit the activity of free metal ions of Cd, Zn, or Cu, using specific ion electrodes and Donnan dialysis. Qualitative changes in soil organic matter will be evaluated. For Pb, in cooperation with EPA
IINERT Action Team, ARS will conduct rat bioassays of Pb bioavailability in Pb-contaminated soils treated with promising remediation technologies. EPA will attempt to characterize changes in Pb speciation in the treated soils.
When bioassay data are available on soils from field test sites (e.g. Joplin, MO), where several treatments were used, chemical extractions to estimate soil Pb bioavailability will be compared to rat and pig bioassays.