Résumé des résultats (Abstract)
(Anglais)
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This European project deals on groundwater risk assessment at contaminated sites. The objective of the contribution of the EPFL is to quantify the potential for intrinsic bioremediation (=natural attenuation) of volatile and semivolatile organic pollutants in the unsaturated zone above groundwater resources. In a large-scale lysimeter, the natural attenuation of fuel compounds has been studied in a sandy unsaturated zone (Pasteris et al., 2002). Biodegradation rates were determined for 12 petroleum hydrocarbons under warm summer conditions. It was found that the gasoline additive Methyl-tert-butyl-ether (MTBE) was the least biodegradable and most water-soluble compound, posing a significant risk for groundwater resources even at sites with only small amounts of gasoline spilled to soil. The study stimulated a broad discussion about the environmental risk of gasoline additives on the Swiss Radio DRS1 and in several Swiss newspapers. Furthermore, a new test to detect and quantify liquid fuel in the unsaturated zone has been developed (Werner and Höhener, 2002). The test is based on gaseous tracers migrating by diffusive transport through the soil. The test was successfully applied to quantify a buried mass of jet fuel in a sandy soil at an Air Force Base. Further work is performed in 2002 to use diffusive gaseous tracers for the determination of apparent diffusion coefficients in soils and for measuring biodegradation rates and kinetics of volatile organic pollutants.Pasteris, G., Werner, D., Kaufmann, K. Höhener, P., 2002. Vapor phase transport and biodegradation of volatile fuel compounds in the unsaturated zone: a large scale lysimeter study. Environ. Sci. Technol., 36, 30-39.Werner, D. Höhener, P., 2002. Diffusive partitioning tracer test for nonaqueous phase liquid (NAPL) quantification in the unsaturated zone. Environ. Sci. Technol., 36, 1592-99.
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