Environmental Metabolism of Pyrene and 1-Methylpyrene by Nereis diversicolor

Mineral oils from spills contain magnitudes higher proportions of alkylated Polycyclic Aromatic Hydrocarbons (PAHs) compared to unsubstituted PAHs. Despite this, assessments of contaminations are often limited to only consider the “16 USEPA priority PAHs”, which are all unsubstituted. We studied the metabolism of 1-methylpyrene by exposure to the benthic invertebrate Nereis diversicolor in laboratory mesocosms. Analyses of worm, water and sediment extracts were performed by use of Gas Chromatography Mass Spectrometry (GC-MS) and Ultra Performance Liquid Chromatography with UV, Fluorescence and Quantitative Time of Flight Mass Spectrometry detection (UPLC-UV/FLR/QToF). These analyses show formations of known phase II metabolites such as sulphate, glucoronide and glucoside conjugates. However, more than 90% of the metabolites excreted by the organism to water consist of the double benzylic hydroxylated 1COOH-pyrene, not previously reported in relation to ecotoxicology. This metabolite can act as a source to the unsubstituted PAH, pyrene, through environmental decarboxylation processes.