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1B+C Abiotic Transformations + Biodegradation (MOP/37) Biodegradation of BTEX in subsurface environments in relation to geochemistry and microbial ecology of ecosystems. Parsons, John1, Botton, Sabrina 1, van Verseveld , Henk2, 1 University of Amsterdam, IBED, Dept. Environmental and Toxicological Chemistry, Amsterdam, The Netherlands2 Free University of Amsterdam, Dept. Molecular Cell Physiology, Amsterdam, The Netherlands ABSTRACT- The resilience of subsurface ecosystems towards pollution is to a large extent determined by the ability of the intrinsic microbial communities to mineralise chemical contaminants in groundwater. The chemicals of greatest concern as groundwater pollutants are relatively soluble and mobile organic pollutants such as the BTEX group (benzene, toluene, ethylxylene and xylene). The objectives of this research are to characterise the in situ biodegradation of selected contaminants in subsurface ecosystems in relationship to the geochemistry and microbial ecology of these systems and to contribute to the development of a combined geochemical, ecological and environmental chemical framework for the evaluation of the natural attenuation capacity of subsurface environments. In the present study, microcosms and continuous reactor are used to evaluate different aspects of the biodegradation process: 1. Degradation rates in samples from both contaminated and uncontaminated sites. 2. BTEX oxidation coupled with different terminal electron acceptor processes (TEAP). 3. Identification of metabolic pathways and incorporation into biomass by means of 13C-labelled substrates. 4. Detection of the natural isotopic fractionation process. Preliminary experiments with groundwater and sediment samples collected at Banisweld landfill (Boxtel, the Netherlands) are started. Microcosms were prepared with groundwater and Fe-reducing growth medium and spiked with BTEX. An anaerobic continuous reactor characterized by the presence of a filter membrane (0.2 Key words: biodegradation, btex, groundwater |
m) was also started. This retentostat is running with a pure culture of Geobacter Metallireducens, a Fe(III) reducing bacteria able to use toluene as sole carbon source and whose presence in the field was previously observed. Results of the preliminary experiments will be presented at the meeting.