Late Quaternary variability in sea ice cover, primary productivity and terrigenous input along the Transpolar Drift System, Arctic Ocean: A biomarker approach

• Main Author: Hörner, Tanja
• Format: Thesis
• Language: unknown
• Published: 2016
• Subjects: Arctic; Arctic Ocean; Global warming; Kara Sea; laptev; Laptev Sea; Phytoplankton; Sea ice
• Online Access: https://epic.awi.de/id/eprint/42997/; https://hdl.handle.net/10013/epic.49550

Arctic sea ice and river run-off contribute to the Transpolar Drift System of the Arctic Ocean and affect substantially Arctic and global climate. Given the recent environmental changes in the Arctic with drastic sea ice reductions and strongly increasing river run-off, paleoenvironmental investigations are essential to assume prospective impacts resulting from the current global warming. The ideal region to observe paleo-sea ice cover and river run-off within the Arctic are the Siberian marginal seas where enormous amounts of freshwater are drained onto the shelves and sea ice is produced. Therefore, the overall aim of this thesis is to examine how sea ice cover, river run-off and biological production (influenced by both parameters) varied on the Siberian shelves and if they might have affected the Transpolar Drift System during the Deglacial to Holocene. To achieve these objectives molecular biomarkers (sea ice biomarker IP25 the phytoplankton biomarker-IP25 (PIP25 index); the HBI-diene (highly-branched isoprenoids); brassicasterol and dinosterol as indicators for marine organic matter; campesterol and β -sitosterol as indicators for terrigenous organic matter) , were analyzed on five well-dated, continuous sediment cores from the Laptev Sea (Core PS51/154-11, Core PS51/159-10) and Kara Sea (Core BP99-04/7, Core BP00-07/7, Core BP00-36/4) shelves. These biomarker records revealed high-resolution sea ice, river run-off and biological production variability over the last ~17 and ~12 ka, respectively. During the Deglacial, when the sea level was low, a significantly different environment compared to the modern prevailed on the Laptev Sea shelf. The upper continental slope was mostly covered with permanent sea ice (probably landfast ice) between 17.2 and 16 ka. In addition, river run-off and biological production were extremely restricted. In the course of the Holocene transgression the proportion of the organic carbon sources changed on the Laptev Sea shelf reflected by a long-term decrease of terrigenous ...