Pore waters, iodine concentration

Iodine in sediments is supplied from dead organisms and decayed compounds. When detritus in the sediments is decomposed, iodide is liberated under anoxic conditions and diffused in pore water (the concentration is very high). The iodide is partly diffused in seawater, thus higher concentration of iodide was observed in and near the bottom water and the concentration decreased with the distance from the water-sediment interface. The iodide produced on the bottom is very slowly oxidized to iodate in the deep... 

In pore waters the dissolved T concentrations, which are higher than the total iodine concentration in seawater, can be observed with decomposition of particulate organic matter (e.g., Figure IB). In Figure IB the T pore-water concentrations are in micromolar units, compared to the total iodine concentration in seawater of <0.5 (jlM. Thus, the pore waters contain several times the amount of iodine that is found in seawater. Increased T concentrations and significant amounts of organic iodine are found in anoxic basins such as the Black Sea (29, 39, 40). 

Although iodine in oceans is only 0.8% of the total iodine on the earths crust (Muramatsu and Wedepohl, 1998), it enters the human food chain via three important processes (1) the evaporation of iodine from seawater into the air, its subsequent deposition onto soils and in fresh water, and final incorporation into terrestrial plants and animals (2) a higher incorporation into microorganisms, seaweeds, and fish, which are used as food and nutritional supplements and (3) extraction of iodine from pore water that contains no sediments and higher concentrations of iodine and using it for various purposes, e.g., as an additive to edible salt. 

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