ABSTRACT
The soil complex discussed in this chapter is characterized by a high self-purification potential even under conditions of high contamination. Actually, most organic contaminants can be degraded by the autochthonic microflora, i.e., by microorganisms that are normally present in the contaminated soil. This could be confirmed by the results of investigations of the biological vitality and degradative activity of a black sandy soil sample (l00 kg) taken from a former tar oil processing plant extremely heavily contaminated with PAH (104,000 mg of analytically detectable PAH per kilogram of soil dry matter) [1]. The high respiration activity established at the beginning of the experiment and the relatively high respiration toward the end of the experiment (in 307 days) were evidence that PAH degradation essentially resulted in complete oxidation to CO2 , About 92% detoxification of the soil was detected (test with luminescent bacteria). However, aromatics containing five or more rings were not degraded. High molecular weight PAHs or PAH transformation products can be absorbed by the soil organic matter or form a covalent bond with it and thus remain in soil in the composition of humus substances.
