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MUTAGENICITY OF PAH-CONTAMINATED SOILS DURING BIOREMEDIATION
WHITE, P. A., K. LYNES, I. LAMBERT, S. LUNDSTEDT, L. OBERG, AND L. D. CLAXTON. MUTAGENICITY OF PAH-CONTAMINATED SOILS DURING BIOREMEDIATION. Presented at 20th International Symposium on Polycyclic Aromatic Compounds, Toronto, ON, CANADA, August 21 - 26, 2005.
Bioremediation of contaminated soils is considered an effective method for reducing potential health hazards. Although it is assumed that (bio)remediation is a detoxifying process, degradation products of compounds such as polycyclic aromatic compounds (PACs) can be more toxic than the parent compounds. Remediation of a PAC� contaminated soil contaminated from an aged gasworks site in Stockholm, Sweden was carried out using a pilot-scale (750 L) bioslurry. Subsequent chemical analyses followed changes in the concentrations of PACs and PAC derivatives at remediation days 0, 3, 7, 24 and 29. Extract fractions, enriched non-polar neutrals and polar aromatics respectively, were also examined for Salmonella mutagenicity. Mutagenicity assessment employed standard Salmonella tester strains (e.g., TA100 and TA98) as well as strains that have been metabolically enhanced for the detection of nitroarenes and aromatic amines (e.g., YG1041 and YG1042). Extensive chemical analysis at remediation days 0, 3, 7, 24, and 29 revealed noteworthy carcinogenic PACs such as benz[a]anthracene, benzo[a]pyrene and dibenz[ah]anthracene, as well as other PACs, alkyl-PACs, 0- and S�heterocyclics, N-heterocyclics, and oxy-PACs. The concentrations of most low molecular weight PACs (e.g., anthracene, benz[a]anthracene) decreased by 30-90% over the course of the remediation. However, several oxy-PACs (e.g., 4-oxapyrene-5-one, 1-acenaphthenone) increased in concentration during the remediation, and several homocyclic PACs (e.g., indeno[1,2,3,cd]pyrene, benzo[ghi]perylene) remained virtually unchanged. The mutagenicity results revealed an increase in frameshift mutagenicity (e.g., TA98 and YG1041) both with and without S9 activation between remediation day 0 and day 29. YG1041 results with S9 showed 8- to 32-fold increases in mutagenic activity, suggesting an increase in the concentration of aromatic amines. More moderate increases in mutagenicity were observed for TA98 with and without S9 (i.e., 3- to 8-fold), and YG1041 without S9 (i.e., 2-fold). Chemical fractionation suggests an increase in the concentration of hitherto unidentified non-polar neutrals and polar aromatics that are Salmonella mutagens.