PAHs: Rapid estimation of their bioavailability in soil

The present work focuses on the setup of an extraction technique using supercritical carbondioxide for the selective removal of accessible pollutants out of soil. Data obtained under 'mild' and 'rough' extraction conditions are correlated to bioavailability studies. Hence, biodegradation experiments have been accomplished determining the influence of the contract time (ageing) of pollutants (phenanthrene, anthracene, fluoranthene and pyrene) in two different types of soil (silty loam and loamy sand) on the bioavailability of respective PAHs and thus their biodegradation kinetics. The ageing of pollutants in loamy sand soil exhibits only a modest reduction of the degradation rate of respective pollutants, and ageing phenomena could not be detected by the application of the developed Supercritical Fluid Extraction (SFE) method. However, in aged silty loam soil results indicate good correlation between reduced SFE-extractability and a decrease in biodegradation as a consequence of reduced bioavailability of contaminants. In this case long term degradation procedures using microorganisms can now be supported by chemical-physical methods to estimate the bioavalability of ubiquitous contaminants like PAHs in soil and hence predict the bioremediation success of a respective contaminated site.