Hydrocarbons and metabolites in english sole (Parophrys vetulus) exposed simultaneously to [3H]benzo[a]pyrene and [14C]naphthalene in oil-contaminated sediment

English sole (Parophrys vetulus) were exposed to ${}^3\text{H]benzo}\text{a]}\text{pyrene (B}\text{a]}\text{P}\text{)}$ and ¹⁴C]naphthalene (NPH) in sediment containing 1% Prudhoe Bay crude oil (PBCO). Bioeoncentration values (pmoles of hydrocarbon equivalents in g of dry tissue/pmoles of hydrocarbon equivalents in g of sedimentassociated water (SAW)) for NPH were greater than corresponding values for Ba]P in tissues of fish exposed for 24 h. However, from 24 to 168 h of the exposure, a substamial decline (P < 0.05) in NPH-derived radioactivity and a significant (P < 0.05) increase in Ba]P-derived radioactivity occurred in most of the tissues examined. When fish were transferred for 24 h to sediment free of radioactivity and PBCO, the retention of Ba]P-derived radioactivity in the tissues of fish was considerably greater than that for NPH.Metabolites of Ba]P and NPH in sediment, SAW, liver and bile of fish were characterized by thinlayer chromatography (TLC). For liver, a two-dimensional TLC was devised to separate Ba]P and its metabolites from liver lipids. An important finding was that liver of English sole metabolized Ba]P to a far greater extent than NPH; at 24 h after the exposure, the ratio of concentrations of Ba]P to its metabolites was 1 to 49 whereas that for NPH was 6 to 1. Larger proportions of glucuronide conjugates than sulfate conjugates of both NPH and Ba]P were present in bile of English sole. Naphthalene was largely converted into a glucuronide conjugate of l,2-dihydro-l,2-dihydroxynaphthalene. A number of metabolites of Ba]P known to be toxic to mammals were detected in both liver and bile including 7,8-dihydro-7,8-dihydroxy Ba]P and its conjugates.These findings of extensive metabolism of Ba]P by fish liver very probably explain why Ba]P is usually not detected in liver of fish even when considerable concentrations of Ba]P are detected in the environment of the fish.