A càrrec de Mònica ROSELL (Department of Isotope Biogeochemist Helmholtz Centre for Environmental Research, Alemanya)
Organitzat conjuntament CSIC-UB

Data: 12/11/2010
Hora: 12:00
Lloc: Sala d'actes de l'Institut Jaume Almera

Descripció:
Historically, fuel oxygenates (commonly ethers and alcohols) were developed in the 1970s as octane enhancers to replace toxic additives like tetraalkyl lead compounds, which were phased out of gasoline. Methyl tertiary (tert-) butyl ether (MTBE) has been by far the most commonly used oxygenate. As a result of its intense use and physico-chemical properties, MTBE has become one of the most frequently detected volatile organic compounds in groundwater. Accidental spills and tank corrosion leakage from gasoline stations and refineries are the main sources of MTBE entering the environment. Reliable methods for detecting in situ MTBE biodegradation are crucial for evaluating remediation technologies based on the activities of indigenous MTBE degrading microorganisms.

In the last decade, compound-specific stable isotope analysis (CSIA) has been employed as a tool for demonstrating in situ biodegradation of organic pollutants including fuel oxygenates in contaminated aquifers. This concept relies on the higher kinetic isotope fractionation during microbial biodegradation among other natural attenuation processes and uses the enrichment of heavy isotopes (13C and 2H) in the residual fraction as an indicator for in situ biodegradation. Systematic work in closed system-reference experiments with a variety of MTBE bacterial degraders has shown distint fractionation patterns which are useful for investigating degradation pathways and reaction mechanisms. For example, the variations found among aerobic MTBE degraders suggest more than one reaction mechanism and this might be linked to the involvement of different monooxygenases in the initial enzymatic attack. To confirm this hypothesis, CSIA was applied in combination with molecular methods for examinin