The Arctic Ocean marine reservoir age from historic mollusk collections
To study variability and stability of the Arctic Ocean over longer timescales, beyond historic observations, we rely on environmental reconstructions through analysis of marine sediment cores. Fundamental to these reconstructions is the establishment of chronologies for the records, i.e. dating of sedimentary layers. The standard method for this purpose is radiocarbon dating, but accurate calibrations require knowledge of the regional marine radiocarbon reservoir age offset (ΔR). The reservoir age represents the time lag between the age of radiocarbon in the atmosphere and that of the ocean, and extremely little data for this parameter exists in the Arctic Ocean. The primary aim of this project is to determine the marine reservoir age of large parts of the eastern Arctic Ocean and coastal waters around Greenland.
The main reason why there is so little existing data is that it is impossible to determine the reservoir age from analysis of modern samples. Extensive testing of nuclear weapons in the second half of the 20th century caused major disruptions to the global carbon cycle, and lead to the enrichment of radiocarbon (14C) in modern organic material. To circumvent this problem, this project will use mollusk samples from museum collections, collected during historical expeditions to the Arctic Ocean during the late 19th and early 20th Century. These samples contain a geochemical fingerprint of the ocean in which they lived and are not affected by the modern anthropogenic input of 14C, which makes the historic collections invaluable.
contact: Christof Pearce
