Die Bodenkultur - Journal for Land Management, Food and Environment

A. P. Loibner, M. Holzer, M. Gartner, O. H. J. Szolar and R. Braun:

The Use of Sequential Supercritical Fluid Extraction for Bioavailability Investigations of PAH in Soil


The influence of soil organic matter (SOM) content on the bioavailability of polycyclic aromatic hydrocarbons (PAH) was investigated by performing biodegradation experiments and comparing these data to results from a sequential supercritical fluid extraction (SSFE) method. Two model soils with different SOM (soil 1: 2.1 %, soil 2: 8 %) were contaminated using anthracene oil containing fluoranthene as the major high molecular weight PAH. After spiking, soils were stored for 135 days in order to assess the influence of aging on the biodegradation and extractability of fluoranthene.

Moreover, experiments were also performed on an industrial soil, which was already contaminated several decades ago. For non-aged samples, advanced degradation was achieved in soil 2 (higher in SOM). However, for aged samples, degradation was lower in soil 2 indicating that sequestration was more pronounced in the high organic matter soil. Ta evaluate the retention/release behavior of PAH in soil as an important factor influencing their bioavailability, a SSFE method was developed comprising eight subsequent extraction steps. For aged spiked soils extraction data indicate a reduced recovery when high in SOM. These findings are in line with the respective microbial degradation results. However, for non-aged samples no difference in extraction recovery could be observed for both, low and high organic matter soils. Finally, for industrially contaminated soil an inverse relationship between the molecular weight of PAH and their extraction recovery was observed.

Key words:  PAH, fluoranthene, biodegradation, bioavailability, soil, supercritical fluid extraction, soil organic matter.