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Paper No. 232-5
Presentation Time: 6:20 PM
REMOVAL OF LEAD IN RESIDENTIAL SOILS OF JERSEY CITY USING BIODEGRADABLE CHELATING AGENT-ENHANCED PHYTOREMEDIATION
Lead contamination is a major issue for residential soil around older buildings where lead-based paint was utilized. Lead-contaminated soil and dust are poisonous for humans especially for children younger than 6 years of age. In certain cities, more than half of the existing housing facilities were built before lead-containing paint was banned in 1978, leaving an enormous lead contamination problem. Phytoremediation has proven to be an inexpensive and environment-friendly technology for the cleanup of lead in contaminated sites. However, the efficiency of lead removal by plants depends on the existing forms of lead in soil because only the water-soluble and exchangeable forms of lead in soil can be taken up by plants. To broaden the application of phytoremediation in a variety of soil types, this study investigated the effects of a biodegradable chelating agent, ethylenediaminedisuccinic acid (EDDS), on the removal of lead through phytoremediation using vetiver grass (Chrysopogon zizanioides L.). Field studies were conducted in three residential backyards of Jersey City, New Jersey. Results showed that the application of EDDS at 10 mmol per kg soil could immediately enhance lead uptake by vetiver grass. Lead concentrations in the roots of vetiver grass increased by 27-283% while the total lead concentrations in the testing fields decreased by 4-14%. To explore the impact of EDDS on lead removal, geochemical soil lead forms (i.e., water-soluble, exchangeable, carbonate bound, iron/aluminum bound, organic bound, and residual bound fractions) were investigated through sequential extraction. By applying EDDS, approximately 3-38% of the bound lead fractions were converted to water-soluble and exchangeable forms, which were subsequently taken up by vetiver grass. The results demonstrate that EDDS could convert unavailable forms of lead to plant-available forms, thus enhancing plant uptake and facilitating phytoremediation.