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IN SITU SOIL TREATMENTS TO REDUCE THE PHYTO- AND BIOAVAILABILITY OF LEAD, ZINC, AND CADMIUM
Citation:
Brown, S. L., R. L. Chaney, J. Hallfrisch, J A. Ryan*, AND W. R. Berti. IN SITU SOIL TREATMENTS TO REDUCE THE PHYTO- AND BIOAVAILABILITY OF LEAD, ZINC, AND CADMIUM. JOURNAL OF ENVIRONMENTAL QUALITY 33(2):522-531, (2004).
Description:
A study was established in Joplin, MO near a former Pb smelter to test a range of treatments to reduce the avialability of Pb, Zn, and Cd in situ. Soil from the field was incubated in lab studies prior to amendment addition in the field. Treatments induded P added as triple super phosphate (TSP), H3PO4 and rock phosphate; a high Fe municipal biosolids compost, and a high Fe by-product of titanium processing (Fe Rich) These were applied singly and in combination. Field measures included fescue (Festuca elatior cv, K31 metal concentrations and in vitro extracts. Reductions were observed across all measurements parameters but were not consistent. In the feeding study, the 1 % P as H3PO4 treatment resulted in an average decrease of 26% in rats (across all organs) Pb concentration over the control soil. The 2.5%Fe + 1 %P as TSP and 10% Compost treatments showed an equivalent or greater
reduction in Pb (39 and 26%, respectively). The 3.2%P as TSP and the 1 %P as H3PO4 treatments showed the most pronounced reduction in in vitro extractable Pb from field samples
(59%). However, the in vitro extraction (pH 2.2) did not reflect decreases observed in the in vivo study with the 1% H3PO4 showing a 66% reduction, Compost 39%, and the 2.5%Fe+ 1 %P a 50% reduction. The in vitro (pH 1.5) run on field samples showed no reduction in the Compost or Fe treatments. The most effective treatments at reducing plant and in vitro Pb as well as plant Zn and Cd was TSP applied at 3.2% P per dry weight soil and H3PO4 applied at 1 % P per dry weight soil. These results indicate that it is possible to reduce the bioavailability of Pb, Cd, and Zn in field and lab studies but that response across different environments, measurement endpoints and elements of concern vary.