The lipid chemistry of sediments from the St Lawrence estuary. Acyclic unsaturated long chain ketones,diols and ketone alcohols

Long chain unsaturated ketones (C₃₇C₃₉) and two limited series of alkan-1,15-diols and alkan-15-one-1-ols (chain lengths of 30, 31 and 32 carbon atoms) have been isolated from extracts of sediments from the Gulf of St Lawrence and an associated continental slope sample. The detection of these compound classes in these sediments further extends the range of environments within which these compound classes occur. Differences in the absolute abundance of these lipid classes are probably due to variations in the abundances of E. huxleyi or related algae (in the case of the unsaturated ketones). These lipid components were below the limits of detection, however, in all sediments collected from a third, estuarine sampling site. This observation is one feature distinguishing the lipid distribution and thus differences in the contributing biota at the three sites. These data highlight the use of the biological marker approach for assessing the spatial distribution of a contributing organism to sediments within an open estuarine system. The absolute abundance of long chain ketones, diols and ketone alcohols decreased with depth in Gulf sediments (≈2.3 to less than 0.001 μg/g for long chain ketones).