Water Circulation and Marine Environment in the Antarctic Traced by Speciation of 129I and 127I

Emissions of anthropogenic 129 I from human nuclear activities are now detected in the surface water of the Antarctic seas. Surface seawater samples from the Drake Passage, Bellingshausen, Amundsen, and Ross Seas were analyzed for total 129 I and 127 I, as well as for iodide and iodate of these two isotopes. The variability of 127 I and 129 I concentrations and their species ( 127 I − / 127 IO 3 − , 129 I − / 129 IO 3 − ) suggest limited environmental impact where ((1.15–3.15) × 10 6 atoms/L for 129 I concentration and (0.61–1.98) × 10 −11 for 129 I/ 127 I atomic ratios are the lowest ones compared to the other oceans. The iodine distribution patterns provide useful information on surface water transport and mixing that are vital for better understanding of the Southern Oceans effects on the global climate change. The results indicate multiple spatial interactions between the Antarctic Circumpolar Current (ACC) and Antarctic Peninsula Coastal Current (APCC). These interactions happen in restricted circulation pathways that may partly relate to glacial melting and icebergs transport. Biological activity during the warm season should be one of the key factors controlling the reduction of iodate in the coastal water in the Antarctic.