Influence of Oil-Contamination on N-Mineralisation in Soils

The mineralisation of soil organic matter depends on the activity of fungi and bacteria. The different organisms degrade and transform the organic matter by various processes resulting in an availability of nutrients as part natural nutrient cycles. The activity of microorganisms, and thus the intensity of mineralisation, is strongly related to the physicochemical environment (pH, temperature, water content a.o.) and the existence of appropriate substrate and energy sources. As the natural degradation of organic matter includes various hydrocarbons, microorganisms are used to purify soils and wastewater on a technical scale. Investigations of these techniques mostly focus on the degree of mineralisation caused by the activity of heterotrophic microorganisms neglecting those autotrophic organisms (e.g. nitrifying bacteria) that are not directly involved in mineralisation. The strongly increased activity of heterotrophic microorganisms in oil contaminated soil may result in a considerable change of environmental conditions for the anaerobic autotrophic nitrifying bacteria, especially with regard to oxygen supply and the availability of NH3 as electron donator for the first step of nitrification.