Microbial/Plant Approaches for Phytoremediation of PAH- and Crude Oil-Contaminated Soils

摘要

Past GTI research into phytoremediation identified numerous bacteria which are capable of simultaneously degrading hydrocarbon contaminants (especially PAHs) and enhancing growth (and/or survival) of plants. Our goal in isolating these bacteria was to incorporate them into synergistic bacteria/plant phytoremediation approaches, which would lead to faster and/or more complete removal of contaminants than would treatments based on either component (plants or bacteria) alone. We report here the results of several bench-scale experiments conducted in microcosms containing PAHcontaminated soils. Inoculation of alfalfa and/or various prairie grasses with PAHdegrading bacteria (including members of the genera Burkholderia, Sphingomonas, and Mycobacterium) did, in fact, improve removal of contaminants relative to non-inoculated alfalfa, or to inoculation of bacteria in the absence of plants. These lab-scale results have been applied to the design and establishment of a field study at a former MGP site in the Washington, D.C. area. This study is designed to examine the ability of several tree species (which have bee reported in the literature to enhance PAH remediation), both alone and in conjunction with grasses and bacteria, to remediate PAH-contaminated soil. In support of this field work, lab-scale studies are being conducted to generate mass-balances, and elucidate the ultimate fate of PAH in these systems. Finally, GTI will model and examine the possible use of trees which remove large amounts of water from the subsurface (phreatophytes) to achieve hydraulic isolation between PAH-contaminated groundwater at the site and an adjacent river, thus blocking migration of the contaminants off-site by this route.