Oxygenated PAHs in Tokyo Bay sediments: distributional contrast with parent PAHs and their effect evaluations with fish embryos

Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are a group of PAHs derivatives formed by chemical or microbial oxidation that can negatively affect benthic organisms. However, their distribution in coastal sediments remains poorly understood. In the present study, we examined the distribution and ecological risks of oxy-PAHs in sediments collected from 18 sites in Tokyo Bay, Japan. Concentrations of target oxy-PAHs ranged from 10.2 to 1299 ng/g dry weight, generally exceeding previously reported values. Strong correlations were found between oxy-PAHs and sediment carbon content and between oxy-PAHs and parent PAHs, possibly showing common sources or transformation pathways. Lethal and developmental effects were observed in Java medaka (Oryzias javanicus) embryos exposed to the artificial sediments spiked with two oxy-PAHs (7,12-benz(a)anthraquinone and 1,4-naphthoquinone) found at several locations in Tokyo Bay. Both risk quotient indices exceeding 1 were shown at more than 10 sites, and suggest that these 2 substances may pose potential threats to benthic organisms at a number of sites in Tokyo Bay.