|Average concentration in ocean:||460 nmol/kg|
|Residence time:||340,000 yearrs|
The iodate ion (IO3-) is the stable form of iodine in seawater. However, in the euphotic zone, some of IO3- is reduced to I- as phytoplankton reduce NO3- to NO2-.
Distribution in ocean
The vertical profile of IO3- is slightly depleted at the surface due to uptake and removal, while the I- concentation has a surface maximum (data).
The iodine residence time is from Tracers in the Sea (Broecker, W. S. and Peng, T.-H., 1982. Eldigo Press, Palisades, NY). It was calculated from the global average river input.
Iodine has been determined by neutron activation analysis, electrochemical analysis and by inductively coupled plasma mass spectrometry.