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(338) Toxicological monitoring of a contaminant plume for implementing Natural Attenuation as a remediation option. Schirmer, Kristin1, Altenburger, Rolf1, Weiss, Holger1, Schüürmann, Gerrit1, 1 ABSTRACT- "Natural Attenuation" (NA) is increasingly being considered as a cost-effective alternative to active groundwater remediation. NA has been defined by the US EPA as the ability of an aquifer to reduce the mass, toxicity, mobility or volume of contaminants such that human health and the ecosystem are not at risk. Thus, in order to rely on NA as a remediation option, contaminant plumes need to be monitored chemically and biologically. As part of a large-scale interdisciplinary research project, which aims at implementing new assessment methods for NA, we have employed in vitro toxicological tests in order to determine whether the chemically-defined contaminant distribution at the former industrial site Zeitz (Saxony-Anhalt, Germany) agrees with the distribution defined biologically. Two cell lines from rainbow trout liver, R1 and RTL-W1, as well as the green algae Scenedesmus vacuolatus served as reporters of cytotoxicity, cytochrome CYP1A induction, and inhibition of reproduction, respectively. In a first monitoring round, 62 sampling locations were tested at 90% groundwater, the highest concentration achievable in these tests. 22 samples elicited significant cytotoxicity in R1 cells as well as inhibition of reproduction in Scenedesmus vacuolatus. Benzene, toluene, ethylbenzene and the xylenes (BTEX), which occur at high concentrations at the site, only explained part of the toxicity. The presence of other, potentially toxic compounds was indicated also by the ability of 17 groundwater samples to elicit CYP1A, which cannot be induced by BTEX. Thus, based on the toxicological data available to date, chemicals other than BTEX add to the toxicity of the groundwater and the distribution of contaminants appears to stretch further north as previously thought based on chemical data alone. Key words: chemical/biological monitoring, groundwater toxicity, in vitro assays, natural attenuation |
