Aerobic Bioremediation of PAH Contaminated Soil Results in Increased Genotoxicity and Developmental Toxicity

This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the American Chemical Society and can be found at: http://pubs.acs.org/journal/esthag.The formation of more polar and toxic polycyclic aromatic hydrocarbon (PAH)\ud transformation products is one of the concerns associated with the bioremediation of PAH-contaminated soils. Soil contaminated with coal tar (pre-bioremediation) from a former\ud manufactured gas plant (MGP) site was treated in a laboratory scale bioreactor (post-bioremediation) and extracted using pressurized liquid extraction. The soil extracts were\ud fractionated, based on polarity, and analyzed for 88 PAHs (unsubstituted, oxygenated, nitrated,\ud and heterocyclic PAHs). The PAH concentrations in the soil tested, post-bioremediation, were\ud lower than their regulatory maximum allowable concentrations (MACs), with the exception of\ud the higher molecular weight PAHs (BaA, BkF, BbF, BaP, and IcdP), most of which did not\ud undergo significant biodegradation. The soil extract fractions were tested for genotoxicity using the DT40 chicken lymphocyte bioassay and developmental toxicity using the embryonic\ud zebrafish (Danio rerio) bioassay. A statistically significant increase in genotoxicity was\ud measured in the unfractionated soil extract, as well as in four polar soil extract fractions, post-bioremediation (p < 0.05). In addition, a statistically significant increase in developmental\ud toxicity was measured in one polar soil extract fraction, post-bioremediation (p < 0.05). A series\ud of morphological abnormalities, including peculiar caudal fin malformations and\ud hyperpigmentation in the tail, were measured in several soil extract fractions in embryonic\ud zebrafish, both pre- and post-bioremediation. The increased toxicity measured post-bioremediation is not likely due to the 88 PAHs measured in this study (including quinones), because most were not present in the toxic polar fractions and/or because their concentrations did not increase post-bioremediation. However, the increased toxicity measured post-bioremediation is likely due to hydroxylated and carboxylated transformation products of the 3- and 4-ring PAHs (PHE, 1MPHE, 2MPHE, PRY, BaA, and FLA) that were most degraded