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 bio degradation was investigated in three: artificially contaminated AhA1-horiz on/compost-mixtures spiked with (a) a PAH-mixture consisting of nine compou nds, (b) a hetero-PAH-mixture consisting of ten compounds, and (c) a mixtur e of these nine PAHs and ten hetero-PAHs. 30 PAH-metabolites and 4 hetero-P AHs metabolites were identified by HPLC-DAD and GC-MSD, predominantly aroma tic ketones, quinones, hydroxylated and dihydroxylated compounds. Several o f these metabolites such as 1-acenaphthenone, 4-hydroxy-9-fluorenone, 9,10- phenanthrenedione, 1-hydroxyacenaphthene, dihydroxyacenaphthene or the hete ro-PAH-metabolites 2-hydroxyquinoline, dibenzothiophenesulfoxide, dibenzoth iophenesulfone, and hydroxydibenzofuran have not been identified in previou s soil degradation studies. The vast majority of extractable metabolites sh owed only short-time accumulation followed by either further degradation or formation of bound residues, respectively. In the PAH- and hetero-PAH-cont aminated 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.