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In Situ Soil Treatments to Reduce the Phyto- and Bioavailability of Lead, Zinc, and Cadmium

Brown, Sally, Chaney, Rufus, Hallfrisch, Judith, Ryan, James A., Berti, William R.
Journal of environmental quality 2004 v.33 no.2 pp. 522
polluted soils, lead, zinc, cadmium, processing waste, bioavailability, soil amendments, remediation, phosphorus, biosolids composts, iron, Festuca arundinacea, rats, bioassays, laboratory animals, in vitro studies, extraction, in vivo studies, Missouri
A study was established near a former Zn and Pb smelter to test the ability of soil amendments to reduce the availability of Pb, Zn, and Cd in situ. Soil collected from the field was amended in the lab with P added as 1% P-HPO, biosolids compost added at 10% (referred to hereafter as “compost”), and a high-Fe by-product (referred to hereafter as “Fe”) + P-triple superphosphate (TSP) (2.5% Fe + 1% P-TSP) and incubated under laboratory conditions at a constant soil pH. Changes in Pb bioavailability were measured with an in vitro test and a feeding study with weanling rats. Field-amended and incubated soils using these plus additional treatments were evaluated using the in vitro extraction and tall fescue (Schreb. cv. Kentucky-31) metal concentration. Reductions were observed across all parameters but were not consistent. In the feeding study, the 1% P-HPO and compost treatments resulted in a decrease of 26% in rat tissue Pb concentration compared with the control soil. The 2.5% Fe + 1% P-TSP showed a 39% decrease. The 1% P-HPO treatment caused the greatest reduction in in vitro extractable Pb from field samples (pH 2.2) with a measured reduction of 66%, while the compost treatment had a 39% reduction and the 2.5% Fe + 1% P-TSP treatment a 50% reduction. The in vitro extraction (pH 1.5) run on field samples showed no reduction in the compost or Fe treatments. The 1% P-HPO treatment was the most effective at reducing plant Pb, Zn, and Cd.