Radionuclides as tools to study the role of the Arctic Sea Ice in the interception, transport and redistribution of particulate matter and chemical species

• Main Authors: Camara-Mor, P., Masque, P., Garcia-Orellana, J., Cochran, J. K., Mas, J. L., Chamizo, E., Hanfland, Claudia
• Format: Conference Object
• Language: unknown
• Published: 2011
• Subjects: Arctic; Arctic Basin; Arctic Ocean; Sea ice
• Online Access: https://epic.awi.de/id/eprint/23811/; https://hdl.handle.net/10013/epic.36747

The Arctic Ocean is characterized by being covered by sea ice with a large degree of seasonal variability between summer and winter. Along the whole life cycle of sea ice, diverse physical and chemical processes determine the concentration of the sea-ice sediments (SIS) and the chemical species entrapped in it and their final fate. Initially, sea ice incorporates particles (SIS) and associated chemical species (metals, nutrients, contaminants, etc.) during its formation mainly in the continental shelves, while dissolved solutes are excluded. As sea ice drifts offshore to the central Arctic Basin, it intercepts chemical species from the atmosphere and, the sediments in the ice may also incorporate some chemical solute compounds from the surface waters by scavenging (although this is likely small). Eventually, transported components, chemical species and SIS, are released to the underlying water column during melting. Thus, sea ice becomes an important transpo rt and distribution agent. However, the efficiency of interception of atmospheric fluxes by sea ice, the origin of the entrapped SIS and transit times of sea ice in the Arctic, as well as the importance of the transport of chemical species and particulate matter (SIS) and its release in the ablation area are all poorly understood. In an attempt to address these questions, a suite of natural (7Be and 210Po-210Pb) and artificial (137Cs, 239,240Pu) radionuclides were analysed in samples from precipitation, sea ice, surface water, water beneath ice and sea-ice sediments collected during the ARK XXII/2 expedition in 2007. The distributions of 7Be and 210Pb showed enrichment in sea ice (129 ± 90 and 5.1 ± 2.9 Bq·m-3, respectively) with respect to surface water (7.1 ± 1.3 and 1.1 ± 0.36 Bq·m-3, respectively). Given that only 4% of the total amount of 210Pb in sea ice comes from seawater and that any 7Be (T1/2 = 53 days) trapped in sea ice during its formation has decayed during drift, the direct atmospheric flux appears as the most important source of both ...