A COMPARISON OF DISSOLVED IODINE CYCLING AT THE BERMUDA ATLANTIC TIME-SERIES STATION AND HAWAII OCEAN TIME-SERIES STATION

The results of analyses of samples from the Bermuda Atlantic Time Seri es (BATS) and Hawaii Ocean Time-series (HOT) for dissolved iodine spec iation are presented. At both sites iodate is reduced to iodide in sur face waters by biological processes, but the iodide concentrations in the upper 100 m at the HOT site are approximately twice those at the B ATS site. Using published estimates of surface water residence times a nd primary productivity at each station we use the differences between the two sites to derive an estimate of the in situ rate of iodide oxi dation and the relationship between iodate reduction and primary produ ction using a simple mass balance model. The model results suggest tha t on an annual basis iodide oxidation is relatively fast (half-life ab out 70 days) and that biological iodate reduction to iodide is about 1 00 times faster than iodide incorporation into particulate organic car bon. Copyright (C) 1996 Elsevier Science Ltd