Hydrocarbons in the Sediments of the Bermuda Region: Lagoonal to Abyssal Depths

Abstract

Gas chromatographic analyses of the pentane fraction derived from surface sediments collected from 20 stations (50 cores) around Bermuda from the subtidal zone to 40 m depth and one deep-water sediment sample from 1400 m depth showed that outside the protective boiler reef, the total aliphatic (pentane-extractable) hydrocarbon content was less than inside the reef (3-10 jg/g dry weight outside vs. 10-65 jg/g inside). Samples from the 1400 m depth showed < 1.0 jg/g aliphatic hydrocarbon content. The chromatograms from the shipping channels showed fresh petroleum source concentrations of 8-31 jg/g; harbors yielded chromatograms typical of chronic petroleum contamination, with 30-110 jg/g concentrations. Several biogenic compounds (including C15 and C17 n-alkanes and most probably derived from marine algae) were observed, in addition to the petroleum-derived hydrocarbons. The criteria adopted for distinguishing biogenic and petroleum hydrocarbons are given.