The significance of radiolarian isotopic signals for paleoceanographic reconstructions

• Applicant: Dr. Andrea Abelmann
• Subject Area: Oceanography
• Term: from 2006 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 27111597

The proposed study aims to further develop the novel approach to reconstruct past nutrient utilization and productivity based on silicon isotopes (δ30Si) from radiolarian and diatom opal. Such reconstruction is crucial for the understanding of past nutrient and carbon cycling in areas characterized by strong deposition of biogenic opal, such as the Southern Ocean, and its effect on global biogeochemical cycles and climate development. Currently we have started the funded one-year study (November 2006), which will concentrate on the establishment of isotope records from sediment cores PS2498-1 and PS1778-5, located in the Subantarctic and the Polarfront Zone of the Atlantic Southern Ocean, respectively. This will provide first information on glacial-interglacial variability in different Southern Ocean zones and from heterotrophous and autotrophous siliceous microplankton. Following the reviewer’s suggestions, this pioneering study will be augmented during a second year (requested herein) by the systematic study of surface sediments from different physical and biological settings in the Atlantic, the Indian and the Pacific sectors of the Southern Ocean. This will include the investigation of the δ30Si signal from specific size class radiolarians and diatoms as well as a radiolarian census. The proposed project will provide the first information about latitudinal changes of isotopic signals in siliceous microorganisms in comparison to the different hydrographic and biological regimes of the Southern Ocean. Such results will provide the basic reference for further paleoceanographic interpretation of siliceous microplankton isotope records. This study is part of the International Polar Year 2007/08 BIPOMAC (“Bipolar Climate Machinery”) network aimed to document and decipher polar processes regulating climate development and variability.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Infrastructure area - Antarctic Research with Comparative Investigations in Arctic Sea Ice Areas
• Participating Person: Dr. Christina de la Rocha