IODINE SPECIATION IN THE NORTHWESTERN MEDITERRANEAN-SEA - METHOD AND VERTICAL PROFILE

Iodine speciation analysis was carried out upon seawater samples colle cted in July 1993 at the Dyfamed station (43-degrees 25'N, 7-degrees 5 2'E) located in the northwestern Mediterranean Sea. Dissolved iodate a nd iodide were directly determined by differential pulse polarography and cathodic stripping square wave voltammetry, respectively, and orga nically bound iodine was estimated by wet-chemical oxidation with sodi um hypochlorite. Iodate is the predominant species ranging from 416 nM in surface waters to 480 nM in bottom waters. Iodide is present in si gnificant concentrations up to 60 nM in surface waters, undetectable b etween 500 and 1000 m depth and present in very low but measurable con centrations (about 6 nM) in deep waters. The vertical profile of total free iodine demonstrates observable removal from surface waters, slig ht enrichment at about 200 m depth and constant there below. Up to 40 nM of organically bound iodine has been estimated between 20 to 30 m. Factorial analysis of different iodine species with biologically relev ant parameters provided strong evidence for iodine biophilic features.