Fate of pyrene in contaminated soil amended with alternate electron acceptors

Creosote-contaminated soil samples from the Libby Ground Water Contaminatio n Superfund Site in Libby, MT, were amended with the potential alternate el ectron acceptors (AEA) nitrate (KNO3), manganese oxide (MnO2), and amorphou s iron oxyhydroxide (FeOOH) and incubated at low oxygen tensions (0-6% O-2) . The fate of C-14-pyrene was evaluated with respect to the different soil amendments. The fate of C-14 from the radiolabeled pyrene with regard to mi neralization and bound residue formation within soil humic fractions was no t significantly different from controls for the iron and manganese amended soils. Nitrate amendments appeared to stimulate C-14-pyrene mineralization at a level of 170 mg NO3-N kg(-1), and inhibit mineralization at 340 Ing NO 3-N kg(-1). The stimulatory effect did not appear to be the result of nitra te serving as an electron acceptor. Although AEA amendments did not signifi cantly affect the rate or extent of C-14-pyrene mineralization, results of oxygen-deprived incubations (purged with N-2) indicate that AEA may be util ized by the microbial community in the unsaturated contaminated soil system . (C) 2001 Elsevier Science Ltd. All rights reserved.