The distribution of iodine in the Baltic Sea during summer

Iodate and total inorganic iodine concentrations have been measured in near surface and intermediate waters (0-200 m) of the Baltic Sea, south of lati tude 59 degreesN, during August 1999. Additionally, organic-iodine was meas ured at seven selected stations in August 2000. Overall, iodine's behaviour is not conservative and is consistent with its pattern of biogeochemical c ycling observed elsewhere in the oceans coupled with the particular hydrogr aphic characteristics of this fjord. Thus, total inorganic iodine concentra tions rationalised to salinity 35 were higher (similar to 0.60 muM) in wate rs on the bottom or at about 200 m, above the Deeps, presumably as a result of re-mineralisation. Meanwhile, iodate was more concentrated near the sur face than on the bottom, suggesting iodate reduction in the near bottom wat ers. Despite the overall non-conservative pattern, in much of the water bod y total inorganic iodine appeared to mix conservatively between water outsi de the main, Darss Sill (SigmaI = 0.16 muM, 13 S) and that within the Sea, itself (SigmaI = 0.09 muM, 6 S) Meanwhile, iodate concentrations were high in the intruding water but very low behind the sills (similar to 0.04 muM), showing little change at salinities less than 12. organic iodine was gener ally low (0.010 muM) but as high as 0.040 muM at 60 m at one station. (C) 2 001 Elsevier Science B.V. All rights reserved.