Circulation of Circumpolar Deep Water and marine environment traced by 127I and 129I speciation in the Amundsen Sea Polynya, Antarctica. (December 2020)

• Record Type: Journal Article
• Authors: Xing, Shan; Hou, Xiaolin; Shi, Keliang; Aldahan, Ala; Possnert, Goran
• Is Part Of: Journal of environmental radioactivity. Volume 225(2021)
• Publication Date: 2020-12
• Subjects: Iodine-129 -- Iodine species -- Circumpolar Deep Water -- Marine environment -- Amundsen sea polynya; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2020.106424
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: The long-lived anthropogenic 129 I released from human nuclear activities has been widely employed as an effective oceanographic tracer to investigate circulation of water masses in marine environment. Depth profiles of seawater collected from the Amundsen Sea Polynya, Antarctica were analyzed for total 129 I and 127 I, as well as their species of iodide and iodate. The measured 129 I concentrations ((1.15–3.43) × 10 6 atoms/L) and 129 I/ 127 I atomic ratios ((0.53–1.19) × 10 −11 ) indicate that anthropogenic 129 I has not only reached the Antarctic surface marine environment but also the deep water due to a strong vertical mixing of water masses. The Circumpolar Deep Water (CDW) flowed southward along continental shelf towards the ice shelf zone (74.25°S) at a depth of 1025 m and then migrated upward and northward to the polynya and finally to the sea ice zone (71.95°S). The maximum upwelling depth of the CDW was around 200 m in the polynya. The source of 129 I − in the polynya is predominantly the intrusion of source waters rather than the in-situ reduction of iodate by phytoplankton, implying a considerably slow reduction process of iodate to iodide in this region. Graphical abstract: Image 1 Highlights: Anthropogenic 129 I has not only reached the Antarctic surface water but also the deep water with a depth of at least 1025 m. The transport pathway of CDW was firstly investigated in the Amundsen Sea Polynya, and its maximum upwelling depth was around 200 m. The reduction of iodate to iodide in the polynya might be a relatively slow process.