Bluhm K.,Leibniz Institute of Marine Science |
Croot P.L.,Leibniz Institute of Marine Science |
Huhn O.,Institute For Umweltphysik Iup |
Rohardt G.,Alfred Wegener Institute for Polar and Marine Research |
Lochte K.,Alfred Wegener Institute for Polar and Marine Research
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2011
The biogeochemistry of iodine in the waters of the Atlantic sector of the Southern Ocean was investigated during the Polarstern cruise ANTXXIV-3 ZERO&DRAKE. The speciation and distribution of iodine (iodate and iodide) in seawater was examined across gradients of iron concentrations and phytoplankton abundance, ranging from an open ocean region along the Zero Meridian to the Weddell Sea and Drake Passage. Iodine cycling in high latitudes differs from that in low latitudes due to differences in the plankton community composition and the physicochemical characteristics. Iodate concentrations ranged between 400 and 450nmolL -1 from the surface to the bottom. Surface concentrations of iodide (17 to over 60nmolL -1) were about an order of magnitude higher than below the pycnocline. The peak values of iodide lay nearly always within the euphotic zone and showed a weak, positive correlation with nitrite concentrations in the upper 200m. In all vertical profiles a pronounced sub-surface maximum in iodide appears between 50 and 200m depth indicating an iodide drawdown at the near surface. Iodide distribution in the Weddell Sea showed elevated levels in Weddell Sea Bottom Water (WSBW) indicating slow oxidation kinetics and the potential for iodide as a tracer of WSBW formation. © 2011 Elsevier Ltd.