Anthropogenic ¹²⁹I in the Baltic Sea

We report here data on the distribution of ¹²⁹I in water of the Baltic Sea and Skagerrak-Kattegat basins obtained through sampling campaigns during the years 2000 and 2001. ¹²⁹I in the water of the Skagerrak-Kattegat shows persistently high concentrations in both the surface and deep parts. A decreasing trend in surface water ¹²⁹I concentration is observed away from the Kattegat basin and into the Baltic Sea. Inventory calculations indicate that at least 95% of the isotope supply to the Baltic Sea is from the North Sea marine water via Skagerrak-Kattegat and only minor part is from riverine inflow and the Chernobyl accident. As the discharges from the nuclear reprocessing facilities were not decreased during the last decade, it is expected that more ¹²⁹I will accumulate in the Baltic Sea and related basins in the future. Consequently, systematic sampling is needed to reevaluate the concentration levels not only in the water, but also in the sediments and biota of the region.