HYDROCARBONS, STEROLS AND ALKENONES IN SINKING PARTICLES IN THE INDIAN-OCEAN SECTOR OF THE SOUTHERN-OCEAN

Hydrocarbons, sterols and alkenones were analyzed in samples collected from a 10 month sediment trap time series deployed in the Indian Ocea n sector of the Southern Ocean. Fluxes and within-class distributions varied seasonally. During higher mass and organic carbon (OC) flux per iods, which occurred in austral summer and fall, fresh marine inputs w ere predominant. Vertical fluxes were most intense in January, but lim ited to one week in duration. They were, however, low compared with ot her oceanic regions. In contrast, low mass and OC Bur periods were cha racterized by a strong unresolved complex mixture (UCM) in the hydroca rbon fraction and a high proportion of stanols as a result of zooplank tonic grazing. Terrigenous inputs were not detectable. The alkenone co mpositions were consistent with previous data on suspended particles f rom Antarctic waters. However, U-37(K') values diverged from the linea r and exponential fits established by Sikes, E. L, and Volkman, J. K. Calibration of alkenone unsaturation ratios (U-37(K')) for paleotemper ature estimation in cold polar waters. Geochimica et Cosmochimica Acta , 1993, 57, 1883-1889], in the low temperature range. The seasonal pat tern of alkenone production implied that IPT (integrated production te mperature) is likely to be strongly imprinted by austral summer and fa ll SST (sea surface temperature). (C) 1998 Elsevier Science Ltd. All r ights reserved.