ORGANIC-MATTER IN DEEP-SEA SEDIMENTS FROM THE PORCUPINE ABYSSAL-PLAIN IN THE NORTHEAST ATLANTIC-OCEAN .1. LIPIDS

The extractable lipids of four undisturbed sediment cores from the Porcupine Abyssal Plain, in the north-eastern Atlantic Ocean, have been analysed. Several compound classes including n-alkanes, n-alcohols, alkanoic and alkenoic acids, sterols, triterpenoids and alkenones were present in most of the samples. Surficial sediments showed evidence of mixed marine and terrigenous organic matter, the latter presumably being higher plant-derived. There was, however, considerable variability in the distributions of lipids in the surficial sediments; this is consistent with photographic evidence of the patchiness of the Porcupine Abyssal Plain sediments, which are strongly influenced by the benthic faunal community. In general, the concentrations of most compounds (with respect to total organic carbon) are attenuated with depth in the sediments, although the ''higher plant'' signal is apparently more recalcitrant than the ''marine'' signal. There is also evidence of significant down-core variability in some of the cores.