Geochemical significance of the lipid assemblages from the Laguna de las Madres (Huelva, Spain) peat deposit

7 páginas, 3 figuras, 1 tabla, 32 referencias.-- Comunicación presentada al citado congreso internacional, celebrado del 15-18 de julio 2002, en Alcalá de Henares, Madrid, España.-- [email protected]

Vertical distributions of Iipid compounds along a sediment core from Laguna de las Madres (Huelva, Southern Spain) peat bog was analysed by gas chromatography-mass spectrometry (GC-MS). Two peat sections taken at different depths were studied in order to get information on the structure of the trophic system and the diagenetic processes of organic matter (OM) in this depositional environment. No qualitative f1uctuations downcore were observed in the patterns of the numerous alkyl series {n-alkanes, n-fatty acids. n-alkanols and n-alkan-2-ones} identified. Longchain alkylcompounds (>C24) typical of epicuticular waxes from herbaceous plants, predominate in these series. The presence of short-chain n-alkanes, bacterial fatty acids (Cl4' C15 , iso- and unsaturated acids), des-A-triterpenoid hydrocarbons, hopanoids and sorne steroid ketones indicate that intense microbial reworking of the OM took place for the whole range of the geochemical record analysed in this study. Diterpenoid and triterpenoid hydrocarbons with C-backbones assigned to higher plant sources were also present, as well as hopanoids of bacterial origino Steroid ketones and alkanols are dominated by C29 homologues similar, comparable to those derived from Sphagnum species and vascular plants. In general, the distributions of the different biomarker families were not distind enough to be considered as diagnostic tracers of any particular input, and therefore no c1ear chemotaxonomic descriptors of the biodiversity changes on the palaeoecosystem along the period of the peat deposit formation could be made.

Peer reviewed