Linking Paleo-Observations with Climate Models in order to understand Holocene environmental variability of coastal East Antartica (HoloAnt)
Final Report Abstract
The reliability of sediment-based paleoclimate reconstructions is particularly depending on the quality of the age determination of these records. Sediment sequences from the Late Pleistocene and Holocene are commonly dated by 14C-analysis. This approach, however, faces some difficulties in the Antarctic region. Core top 14C-ages of sediment records from the Southern Ocean, which are supposed to represent the modern sediment surface often provide ages of up to several thousand years. This is caused by deposition of reworked organic carbon, which is especially relevant in proximity to ice sheets or glaciers, were erosional processes are active. Secondly, the ocean around the Antarctic continent hosts a high and not well-quantified reservoir effect, which is estimated to be around 1100-1300 years in the late Holocene. The objective of the project was to investigate 14C-signatures of different biomarkers (compound-specific radiocarbon analysis, CSRA) in marine sediments to improve chronologies of sedimentary records from Antarctica and thereby enable a better correlation of paleoclimate reconstructions. Within the project we sought to develop new methods for CSRA and for the isolation of diatom sterols in particular. We suggest that sterols derived from phytoplankton reflect the 14C-signal of surface waters and therefore provide a more accurate measure of sedimentation age than bulk 14C-ages. A combination of wet chemical and gas chromatographic (preparative gas-chromatography) methods was used for the purification of sterols.
