PH08 Restoration of Contaminated Sites
Exhibit Hall
8:00 AM - Thursday, 13 November 2003
(PH085) Assessing the toxicity of munitions–contaminated water and soil after remediation with zerovalent iron.
Culp, R.1, Lemrick, C.1, Park, J.1, Shea, P.1, 1 University of Nebraska-Lincoln, Lincoln, Nebraksa, USA
ABSTRACT- Appropriate chemical, biological, and physical parameters are sought in judging the severity of contamination and the effectiveness of remediation treatments. It is also critical that treatment products and the remediation process will not adversely affect the environment and human health. We previously demonstrated that zerovalent iron (Fe0) can be used to effectively decrease the concentrations of TNT, RDX, and HMX in water and soil. Our objective was to use Microtox®and fluorescein diacetate (FDA) assays in conjunction with soil respiration measurements to assess changes in toxicity when remediating munitions–contaminated water and soil with Fe0. Soil respiration (determined by oxygen consumption) provided an overall assessment of biological activity in the contaminated and treated soils. The Microtox® assay, which measures changes in the photoluminescence of the bacterium Vibrio fischerii, is gaining interest as a screening tool for toxicity assessment and to predict the outcome of compliance tests. While Microtox EC50 values indicate low toxicity of RDX before and after treatment with Fe0, EC20 values suggest some toxicity after treatment. We found that cationic surfactants can be used to facilitate Fe0–mediated reduction of RDX and HMX but low EC50 values indicate their use may require removal by degradation or strong adsorption as part of the treatment process. The FDA assay can be used for an assessment of soil enzyme activity because FDA is hydrolyzed to fluorescein by lipases, esterases and some proteases. Colorimetric measurement of fluorescein reflected microbial activity and inhibition in munitions–contaminated soils during treatment with Fe0. Our results indicate that the selected tests, when used in combination with chemical analysis and assays of mammalian toxicity, can be valuable tools in evaluating toxicity in contaminated and remediated soil and water.
Key words: toxicity, remediation, zerovalent iron, munitions