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(W/EH021) Measuring the spatial distribution of hydrophobic toxic groundwater contaminants and estimating their mobility in aquifer using long-term in situ samplers. Vrana, Branislav1, Altenburger, Rolf1, Paschke, Albrecht1, Popp, Peter1, Schüürmann, Gerrit1, 1 ABSTRACT- Semipermeable membrane devices (SPMDs) present a groundwater sampling method that is convenient for long-term and time-integrated monitoring of dissolved hydrophobic organic contaminants. Using this method, artifacts are avoided which are commonly involved in pumping, transferring and storing of groundwater samples. In this study, SPMDs were used for measuring the spatial distribution and toxic potential of lipophilic groundwater contaminants in a highly polluted industrial area of Bitterfeld in Saxony-Anhalt, Germany. The main groundwater contaminants in Bitterfeld are thought to be water soluble and volatile. However, there is a lack of information about the lipophilic contaminants and their relative contribution to the overall groundwater toxicity. SPMDs were exposed in six sampling wells over a time period of 20 days. Identified and quantified pollutants in the SPMD extracts included halogenated benzene derivates, organochlorine pesticides, polyaromatic hydrocarbons and sulfur containing heterocyclic compounds. Ambient water concentrations were calculated from SPMD concentrations in each sampling well using a model taking into account both the contaminant uptake kinetics by SPMDs and the groundwater flux in the aquifer. In addition to instrumental methods of analysis, SPMD extracts were examined by several short-term bioassays (Microtox, Daphnia immobilization and the algal growth inhibition). The results suggest that the mobility of hydrophobic groundwater contaminants in dissolved form is very limited. The observed toxic effects of the extracts correlate well with the degree of groundwater contamination with hydrophobic chemicals. A coupling of biomimetic extraction with toxicity testing seems to be a promising tool for an easy identification of the toxic potential of the lipophilic groundwater pollutants. Key words: groundwater sampling, persistent organic pollutants, SPMD, bioassays |
