ORIGINS OF HYDROCARBONS IN BERING SEA SEDIMENTS .1. ALIPHATIC-HYDROCARBONS AND FLUORESCENCE
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Sixty-three samples from thirteen gravity cores were analyzed by GC/FID, qualitative GC/MS and fluorescence spectroscopy to determine the concentration, distribution and sources of hydrocarbons in Bering Sea sediments. Aliphatic hydrocarbons and fluorescence associated with aromatic compounds were detected in sediments at all locations. The sediments contain variable amounts of marine biological debris, terrigenous plant biowaxes, recycled continental material, petroleum and combustion derived hydrocarbons. Hydrocarbon concentrations were low and similar to previous reports from the Alaskan outer continental shelf (average UCM and total n-alkanes varied from 10.7 to 73.3 and 2.6 to 4.6 g/g, respectively). Olefins, of a presumed biological origin, were widely distributed throughout Bering Sea sediments. The presence of a complete suite of normal alkanes, isoprenoids, an unresolved complex mixture, alkylated PAHs, and mature biological markers suggest that locations in the western and southern Bering Sea are contaminated with petroleum. This petroleum may be derived from natural seepage, recycled mature continental material, autochthonous exposed immature/mature sediments, and/or deposition of water column tarballs. The petroleum at one southern Bering Sea location is typical of a condensate and is significantly different from that observed at western Bering Sea locations. Vertical distributions and the presence of significant amounts of volatile hydrocarbons suggest that petroleum seepage is a likely source of contamination at these locations. 1991.
