Effects of Nereis diversicolor on the Transformation of 1-Methylpyrene and Pyrene: Transformation Efficiency and Identification of Phase Ⅰ and Ⅱ Products

摘要

Transformation of nonsubstituted and alkyl-substituted polycydic aromatic hydrocarbons (PAHs) by the benthic invertebrate Nereis diversicolor was compared in this study. Pyrene and 1-methylpyrene were used as model compounds for nonsubstituted and alkyl-substituted PAHs, respectively. Qualitative and quantitative analyses of metabolites and parent compounds in worm tissue, water, and sediment were performed. Transformation of 1-methylpyrene generated the benzylic hydroxylated phase Ⅰ product, 1-pyrenecarboxylic acid that comprised 90% of the total metabolites of 1-methylpyrene, and was mainly found in water extracts. We tentatively identified 1-methylpyrene glucuronides and 1-carbonylpyrene glycine as phase Ⅱ metabolites not previously reported in literature. Pyrene was biotransformed to 1-hydroxypyrene, pyrene- 1-sulfate, pyrene-1-glucuronide, and pyrene glucoside sulfate, with pyrene- 1-glucuronide as the most prominent metabolite. Transformation of 1-methylpyrene (21% transformed) was more than 3 times as efficient as pyrene transformation (5.6% transformed). Because crude oils contain larger amounts of C_1-C_4-substituted PAHs than nonsubstituted PAHs, the rapid and efficient transformation of sediment-associated 1-methylpyrene may result in a high exposure of water-living organisms to metabolites of alkyl-substituted PAHs, whose toxicities are unknown. This study demonstrates the need to consider fate and effects of substituted PAHs and their metabolites in risk assessments.