Dissolved iodate and total iodine along the British east coast

The distribution of iodine in the North Sea, along the east coast of the Britain in late winter (March 1999) was found to be largely consistent with that reported earlier for the British west coast during various seasons. This supports the contention of a steady state condition for iodine in British waters with mixing between three end-members, one immediately offshore, and others in the central North Sea and the ocean proper (the North Atlantic Current). In the English Channel the oceanic end-member seems to be a more southerly Atlantic water containing significantly lower iodate concentration than the North Atlantic Current. This observation shows that the steady-state condition is limited to high latitudes. In this survey the beginnings of an estuarine mixing system was encountered and, for the first time, this paper has been able to link estuarine iodine chemistry directly to that well offshore. It is deduced that the iodine chemistry of coastal water is established on a longer time scale than that needed for estuarine mixing, and that it is the iodine chemistry of coastal waters which determines the behaviour of iodine in the estuary.