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

Shan Xing; Xiaolin Hou; Keliang Shi; Ala Aldahan; Goran Possnert

doi:10.1016/j.jenvrad.2020.106424

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

J Environ Radioact. 2020 Dec:225:106424. doi: 10.1016/j.jenvrad.2020.106424. Epub 2020 Sep 20.

Authors

Shan Xing¹, Xiaolin Hou², Keliang Shi³, Ala Aldahan⁴, Goran Possnert⁵

Affiliations

¹ State Key Laboratory of Loess and Quaternary Geology, Shaanxi Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi'an AMS Center, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; China Institute for Radiation Protection, Taiyuan, 030000, China.
² State Key Laboratory of Loess and Quaternary Geology, Shaanxi Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi'an AMS Center, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; Department of Environmental Engineering, Technical University of Denmark, Risø Campus, Roskilde, 4000, Denmark; School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; Open Studio for Oceanic-Continental Climate and Environment Changes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237, China. Electronic address: xiho@dtu.dk.
³ School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China.
⁴ Department of Geology, United Arab Emirates University, Al Ain, 17551, United Arab Emirates.
⁵ Tandem Laboratory, Uppsala University, Uppsala, 75120, Sweden.

PMID: 32966942
DOI: 10.1016/j.jenvrad.2020.106424

Abstract

The long-lived anthropogenic ¹²⁹I 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 ¹²⁹I and ¹²⁷I, as well as their species of iodide and iodate. The measured ¹²⁹I concentrations ((1.15-3.43) × 10⁶ atoms/L) and ¹²⁹I/¹²⁷I atomic ratios ((0.53-1.19) × 10^-11) indicate that anthropogenic ¹²⁹I 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 ¹²⁹I^- 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.

Keywords: Amundsen sea polynya; Circumpolar Deep Water; Iodine species; Iodine-129; Marine environment.

MeSH terms

Antarctic Regions
Humans
Iodides
Iodine Radioisotopes / analysis*
Radiation Monitoring*
Water
Water Pollutants, Radioactive / analysis*

Substances

Iodides
Iodine Radioisotopes
Iodine-129
Water Pollutants, Radioactive
Water