Phytoremediation of TNT-Contaminated Soils Using Plants Selected by a Four-Step Screening Procedure

This Phase I project involves the development of a phytoremediation technology for the cleanup of TNT-contaminated soils at the Volunteer Army Ammunition Plant (VAAP) in Chattanooga, TN (an upland site). Phytoremediation, the use of plants to clean up contaminated environments, has a great potential for soils contaminated with TNT. Recent discoveries suggest that intrinsic plant enzymes (not microbial processes) can carry out transformation reactions on some nitroaromatic compounds, and that plants can take up TNT and convert it into harmless derivatives. Previous work on phytoremediation of explosives has dealt almost exclusively with wetland systems. This Phase I project proposes the following novel four-step screening procedure to select plants for the upland phytoremediation of TNT: (1) immunoassay screen, a newly developed method to identify plants containing high levels of TNT-degradative enzyme proteins; (2) whole plant screen, a hydroponic assay system to identify plants that can carry out high rates of transformation of TNT; (3) soils phytotoxicity screen, to identify plants that can become established in explosives contaminated soils from a specific site; and (4) phytoremediation screen, a greenhouse study to identify plants that remove TNT from specific upland soils and that do not accumulate dangerous intermediates (e.g., TAT). From a field of 15 plant candidates, it is anticipated that the procedure will effectively identify useful species. Although the selection process is site specific, the process could be used for soils from any upland site.