Fate of PAHs and Hetero-PAHs during Biodegradation in a Model Soil/Compost-System: Formation of Extractable Metabolites.

The formation of extractable metabolites of PAHs and hetero-PAHs during biodegradation was investigated in three artificially contaminated AhA1-horizon/compost-mixtures spiked with (a) a PAH-mixture consisting of nine compounds, (b) a hetero-PAH-mixture consisting of ten compounds, and (c) a mixture of these nine PAHs and ten hetero-PAHs. 30 PAH-metabolites and 4 hetero-PAHs metabolites were identified by HPLC-DAD and GC-MSD, predominantly aromatic ketones, quinones, hydroxylated and dihydroxylated compounds. Several of these metabolites such as 1-acenaphthenone, 4-hydroxy-9-fluorenone, 9,10-phenanthrenedione, 1-hydroxyacenaphthene, dihydroxyacenaphthene or the hetero-PAH-metabolites 2-hydroxyquinoline, dibenzothiophenesulfoxide, dibenzothiophenesulfone, and hydroxydibenzofuran have not been identified in previous soil degradation studies. The vast majority of extractable metabolites showed only short-time accumulation followed by either further degradation or formation of bound residues, respectively. In the PAH- and hetero-PAH-contaminated soil systems formation of metabolites was delayed due to the delay in degradation of most parent compounds in these soil systems. As some of the PAH-metabolites showed considerable accumulation or persistence at the end of the investigation period, further studies including toxicity testing of metabolites are required to finally assess the relevance of extractable metabolites during bioremediation of contaminated soil. [ABSTRACT FROM AUTHOR]

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