Planktic foraminifera iodine/calcium ratios from plankton tows

Planktic foraminifera test iodine to calcium ratios represent an emerging proxy method assess subsurface seawater oxygenation states. Several core-top studies show lower planktic I/Ca in locations with oxygen depleted waters compared well oxygenated environments. The reasoning behind this trend is that only the oxidized species of iodine, iodate, incorporated foraminiferal calcite. calcite thought reflect iodate contents seawater. To hypothesis, we compare ratios, obtained from plankton tows, published and new concentrations 1) Eastern North Pacific extensive depletion, 2) Benguela Current System moderately concentrations, 3) South Atlantic. We find lowest (0.07 µmol/mol) retrieved Pacific, higher values for samples (up 0.72 tow environments waters, however, are order magnitude core-tops similarly well-oxygenated regions. This would suggest gain post-mortem, either when sinking through water column, or during burial.