Effect of EDTA On Leaching of Lead From Paint Contaminated Residential Soils During Hurricane Sandy.

Application of chelating agents to contaminated soils increases solubility of metals, and thus enhances their phytoextraction. Three lead (Pb) contaminated soils with Pb content between 1268-1880 mg/kg were collected from residential properties in Baltimore, MD. A field study is currently in progress at Stockton, NJ in custom wooden platforms for phytoextraction of Pb by vetiver grass; with fescue grass used as control. The platforms were loaded with 5 inch of play sand and 5 inch Pb of contaminated soil, then vetiver and fescue grasses were planted.  Periodic treatments with a mild biodegradable chelating agent, EDDS is being performed to enhance Pb mobilization. In order to compare the mobilization of lead by EDTA to that of EDDS, EDTA was applied to the Pb-contaminated soils to enhance the solubility of Pb and uptake by vetiver. Three days after the EDTA application, hurricane Sandy hit the experimental site and produced heavy rain and winds. After the hurricane, surface runoff and leachate samples were analyzed.  Data indicate that the application of EDTA resulted in greater solubilization of Pb. The soluble Pb in surface runoff from vetiver grass platforms (2900 - 4400 mg) was marginally lower compared to that of fescue grass platforms (3300 - 4900 mg). Our routine application of EDDS, performed in Oct 2011 and Aug 2012 to the Pb-contaminated soils did not produce such high levels of Pb in the runoff, and remained below 150 mg for all applications. The concentrations of Pb in the leachates (440 - 680 mg) were also higher after EDTA application, compared to that of EDDS. The results indicate that application of EDTA to soils during storms that are likely to result in heavy rains could lead to excessive leaching of metals into the environment.