Speciation and distribution of inorganic iodine in the highly stratified Krka estuary (east coast of the Adriatic Sea) were investigated in the period from December 2000 to April 2001. Conservative behavior of total inorganic iodine was confirmed during the investigated period, but significant temporal and longitudinal variations were also observed. Concentrations of iodate and iodide were less variable in the more saline layers (S ≥10) than in the upper brackish and interfacial layers, indicating lower dynamics and less pronounced influence of secondary processes on the inorganic iodine distribution. An increase in iodate and iodide concentrations toward the estuary mouth was determined in the upper layers. Seasonal variations in iodate and iodide distributions in the brackish layer were indicative of the important role of the freshwater phytoplankton and organic matter for the inorganic iodine cycle in the estuary.Raspodjele kemijskih vrsta anorganskog joda u visoko stratificiranom estuariju rijeke Krke (istočna obala Jadranskog mora) proučavane su u razdoblju od prosinca 2000. do travnja 2001. godine. Kroz promatrano razdoblje potvrđeno je konzervativno ponašanje ukupnog anorganskog joda, a uočene su i značajne vremenske i longitudinalne razlike u raspodjelama. U slanijim slojevima (S ≥10) koncentracije jodata i jodida su znatno manje varirale u usporedbi s onima u bočatom sloju i međusloju, što ukazuje na slabiju dinamiku i slabije izražen utjecaj sekundarnih procesa na raspodjelu anorganskog joda. U gornjim slojevima utvrđen je porast koncentracija jodata i jodida prema izlazu iz estuarija. Sezonske različitosti u raspodjelama jodata i jodida u bočatom sloju pokazatelj su važne uloge riječnog fitoplanktona i organske tvari za kruženje anorganskog joda u estuariju
