THE CHEMICAL-REDUCTION OF MOLECULAR-IODINE ADDED TO SEAWATER, MODELEDAS A SYSTEM OF LINKED 1ST-ORDER REACTIONS

The reduction of molecular iodine added to seawater is modelled as a s ystem of three pseudo-first-order reactions: two in a reversible react ion between hypoiodous acid and another iodine species, possibly the h ypoiodite ion; a third between one of the iodine species and a substra te. The study eliminates molecular iodine as a viable species in the r eduction step. The behaviour of the model toward various settings of i ts mte constants is simulated in detail. The effects of varying the pH of both the receiving seawater and the iodine inoculum are described. Investigations at various temperatures lead to activation energies of 38, 10 and 37 kJ K-1 mol-1 for the reduction reaction and the interco nversion reactions of the iodine species. The apparent rate constant f or reduction of molecular iodine added to oceanic and inshore surface seawaters is found to vary between 0.030 and 2.31 min-1.