REMEDIATING SOIL PB CONTAMINATION, ADDRESSING A SERIOUS HEALTH RISK PROBLEM, SOUTHWEST DETROIT, MICHIGAN USA

The Delray community of southwest Detroit is one of the most depressed areas in southeast Michigan. Surrounded by industry, this residential community suffered from decades of industrial waste discharges that have left Delray with extensive air and soil pollution. Although high unemployment and poverty are major challenges confronting residents in Delray today, the risk of public health problems from Pb, Hg, As and Cr [VI] in the soil may become an even bigger issue and a significant source of concern. Newspaper headlines cite crime, substance abuse, high school and labor force dropout, as being prevalent in Delray, but recent research suggest that soil contamination, which has resulted in elevated blood Pb levels may be an underlying factor. Remedial technologies for the treatment of Pb contaminated soils are very expensive and can result in residues that require further treatment or require the removal of the soil, impractical for community-wide endeavors. Stabilization (immobilization) techniques, which are designed to decrease the bioavailability of the Pb by adding amendments to the soil, can provide cost-effective solutions for community or neighborhood-wide soil contamination. In bench study experiments, three amendments were added to Pb contaminated soils collected from high-risk areas in Delray. The amendments included crushed and powdered phosphate rock, triple sodium phosphate and zeolites. Bioavailability studies were then conducted to evaluate which of the amendments most effectively reduced the biological uptake of Pb. Results showed that among the additives tried, zeolites were not very efficient in Pb immobilization. On the other hand, both the powdered phosphate rock and the Triple sodium phosphate were significantly effective in Pb immobilization reducing the bioavailability of Pb by 70 and 80% respectively