ORGANIC GEOCHEMISTRY OF MARINE-SEDIMENTS OF THE SUB-ANTARCTIC INDIAN-OCEAN SECTOR - LIPID CLASSES - SOURCES AND FATE

Nine sections of core KTB16 (47 degrees 59'98 S, 55 degrees 59'74 E, 4 240 m) taken from the Indian Ocean sector of the Antarctic Polar Front Zone were analyzed for their lipid class and total chlorin contents u sing thin-layer chromatography-flame ionisation detection (TLC/FID). T he following series were included: hydrocarbons, chlorins and chlorin eaters, alcohols, sterols, triacylglycerols, free fatty acids and phos pholipids. For these major classes, the distribution of their individu al components was determined to evaluate the source and fate of each l ipid class. Relationships between the lipid composition of overlying p articles and of buried material were investigated. The sediment-water interface was found to be of primary importance in the biogeochemical transformations occurring in organic matter, such as loss of the major part of the lipids, and formation of a notable unresolved complex mix ture (UCM), of biological origin. Some classes such as chlorin esters appeared to convey their lipid contents from the upper layers without major alteration. In contrast, several other classes, such as storage lipids, appeared to be degraded during sedimentation, indicating exten sive recycling of labile lipids in the water column. The burial effici ency and bacterial inputs downcore were highly variable depending on t he class considered. Several novel compounds are reported. They consis t of alkyl chlorin esters and include a wide variety of saturated and unsaturated long-chain alcohols. Owing to the lack of lipid data in th e study area, these results provide an insight into the various biolog ical and chemical processes occurring in open-sea Antarctic sedimentar y environments. (C) 1997 Elsevier Science Ltd.