Polycyclic aromatic hydrocarbons in benthos of the northern Bering Sea Shelf and Chukchi Sea Shelf

Eighteen polycyclic aromatic hydrocarbons(PAHs) were detected in benthos collected onboard the ‘Snow Dragon’ in the Northern Bering Sea Shelf and Chukchi Sea Shelf during the 6 th Chinese National Arctic Research Expedition(CHINARE 2014). 18 PAHs for all biota samples ranged from 34.2 to 128.1 ng/g dry weight(dw), with the highest concentration observed in fish muscle( Boreogadus saida) samples close to St. Lawrence Island. The PAH composition pattern was dominated by the presence of lighter 3 ring(57%) and 2 ring(28%) PAHs, indicating oil-related or petrogenic sources as important origins of PAH contamination. Concentrations of alkyl-PAHs(1-methylnaphthalene and 2-methylnaphthalene) were lower than their parent PAH(naphthalene) in all biological tissue, and their percentage also decreased significantly( p < 0.05) compared with those in the corresponding sediment. There were no significant relationships between PAH concentrations and trophic levels, which is possibly due to the combined results of the complex benthic foodweb in the subarctic/Arctic shelf region, as well as a low assimilation/effective metabolism for PAHs. According to toxic potency evaluation results from TCDD toxic equivalents(TEQs) and Ba P-equivalent(Ba PE) values, whelk( Neptunea heros) and starfish( Ctenodiscus crispatus) are two macroinvertebrate species showing relatively higher dioxin-like toxicity and carcinogenic risk.