|Mine Waste Technology Program, Phosphate Stabilization of Heavy Metals-Contaminated Mine Waste Yard Soils, Joplin, Missouri, NPL Site (EPA/600/R-04/090) April 2004
This document summarizes the results of Mine Waste Technology Program, Project 22, Phosphate Stabilization of Heavy Metals-Contaminated Mine Waste Yard Soils. Mining, milling, and smelting of ores near Joplin, Missouri, have resulted in heavy metal contamination of the area. The Joplin site was listed on the Superfund National Priorities List in August 1990. High blood levels in young children in the area have prompted efforts to reduce soil-based lead and cadmium health threats. Previous investigations indicate that lead bioavailability can be reduced via the addition of 1 percent by weight phosphoric acid plus 0.05 percent potassium chloride.
The purpose of this study was to determine whether the treatment would be effective in mine waste-affected soils. Bioavailability of lead is determined by measuring lead levels in various tissues from young pigs following ingestion of a known quantity of lead in treated and untreated soil or lead acetate. The data collected for the in vivo study were not sufficient to conclude (at the 95 percent confidence level) that phosphoric acid treatment had any particular effect on lead bioavailability. The results of a parallel in vitro study were more encouraging. The extractable lead was consistently lower in phosphoric acid-treated soils compared to untreated soils.
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