Fuel leakage from underground storage tanks (UST) is a worldwide problem. Gasoline spills introduce contaminates such as BTEX and MTBE. Aquifers contaminated rapidly become anoxic. My research questions were: 1. Does biodegradation of BETX and MTBE occur in Israeli ground water, and if so can we determine its rate? 2. Who are the microbial populations that play a role in natural BTEX and MTBE anaerobic biodegradation in the Israeli coastal aquifer?
To address the first question, groundwater samples from below a gas station, were analyzed for biogeochemical and isotopic indicators of in situ microbial activity. The results indicated manganese, iron and sulfate reduction in the two most contaminated wells .DNA was extracted from water samples from these wells and PCR analysis of the functional gene, bamA, used as biomarker for anaerobic BETX degraders, revealed that the biological potential indeed exists. Initial analysis suggested that these sequences are similar to those found in known anaerobic BTEX degraders. In the case of MTBE, CSIA showed strong carbon isotopic fractionation from δ13C -30‰ to δ13C -14.1‰ and -6.7‰ over one year. This strong enrichment was confirmed in a microcosm experiment with groundwater. Isotopic analysis of this experiment showed strong fractionation of δ13C +10.5‰ and +15.5‰ incubated under methanogenic conditions. MTBE depletion, methane production and production of TBA, were all observed. Thus the results indicate in situ anaerobic biodegradation of MTBE. To address the second question I will perform SIP-DNA with 13C labeled MTBE to try to uncover who are the MTBE anaerobic degraders.
