PW04 Phytoremediation
Exhibit Hall
8:00 AM - Wednesday, 12 November 2003
(PW078) Transport and Fate of Dieldrin in Poplar and Willow Trees.
Skaates, S1, Ramaswami, A1, 1 University of Colorado at Denver, Denver, CO, USA
ABSTRACT- Dieldrin was widely used as an insecticide until 1974, when it's use was banned due to mutagenic effects on mammals. Dieldrin is persisent in the environment, and sorbs strongly to organic matter in the subsurface. Phytoremediation is being considered at a site in Colorado as a possible means to clean-up dieldrin and other organic contaminants in groundwater. However, information on the interaction of dieldrin with trees is needed. The degree of dieldrin partitioning to plant tissue must be known, along with the potential for biodegradation of dieldrin in the microbe-rich tree rhizosphere. In addition, a concern is that dieldrin may be transmitted along the food chain through animals that forage on the leaves and bark of trees. We have performed three types of tests to evaluate transport and fate of dieldrin in poplar and willow trees. The first is a hydroponic exposure test, with small poplar saplings exposed to 10 ppb dieldrin in water for 1-2 weeks to evaluate dieldrin uptake by roots and shoots. The second is a long-term exposure test, using poplar and willow saplings planted in soil watered for several months with 10 ppb dieldrin to evaluate above-ground translocation of dieldrin. The third is a rhizosphere biodegradation test to determine the potential for microbial degradation of dieldrin after exposure of more than six months. By using a novel Solid-Phase Microextraction method, coupled with Gas Chromatography and Dry Electrolytic Conductivity detection, we have evaluated the concentration of dieldrin in water, roots and shoots before and after exposure to dieldrin. From this information, we have derived the Root Concentration Factor (RCF) and shown that limited partitioning occurs to the shoots of the trees. Long-term biodegradation tests are in progress; results to-date indicate that phytoremediation may be applicable for dieldrin.
Key words: phytoremediation, dieldrin, SPME, RCF