Jordfysiske egenskabers påvirkning af mikrobiologisk olienedbrydning i dieselolieforurenet jord

The effect of basic soil-physical properties such as soil texture, soil-water content, effective oxygen diffusivity and permeability on biological oil degradation in two artificially polluted soils was investigated. Experiments were carried out during a six months period in large-scale laboratory lysimeters using packed soils with an initial oil content of 1.5% and using two different strategies for water, nitrogen and phosphorus application. A significant oil degradation was obtained only in the top few cm of the soils where the water content in periods was sufficiently low to allow a large oxygen diffusion from the atmosphere into the soil. The largest oil removal was obtained in the most coarse-textured soil due to more rapid water drainage and oxygen diffusion. The content of easily biodegradable oil compounds and the permeability both decreased during the experiments suggesting an increase in bioactivity and biomass during the six months. The oil degradation was clearly limited by the oxygen supply to the biomass and thus, an additional passive or active soil ventilation seems necessary to obtain any significant in-situ biological oil removal at polluted sites