Sorption and speciation of iodine in boreal forest soil

The speciation and sorption of iodine was studied on humus and mineral soil samples in the initial chemical forms of iodide and iodate. Iodate was reduced to iodide in significant amounts especially in anaerobic soil conditions and in low pH. An unidentified, possible organo–iodine species was detected in humus samples and in aerobic mineral soil at incubation times of 1–21 days and in low pH (4–5). The overall retention of iodide and iodate on Olkiluoto mineral soil was very weak and organic matter proved to be the main sorbent for iodine.