Plutonium in the Southern Baltic Sea and Its Budget and Inflow to the Gulf of Gdansk and the Gdansk Basin. Chapter 8

This study presents the ²³⁸Pu, ^239+240Pu, and ²⁴¹Pu isotopes activity concentrations in different coastal compartments of the southern Baltic Sea. Also, ^239+240Pu inflow, its inventory in the Gulf of Gdansk and the Gdansk Basin, as well as the most important sources, are given, allowing the establishment of the trend in Pu contamination assessment of these areas. The Baltic Sea organisms of different taxonomy or trophic levels did not accumulate plutonium to the same extent. The highest amount of ^239+240Pu existed in the middle pails of sediments, came from global atmospheric fallout and occurred in the mobile, connected to carbonates, fraction. Opposite, the most considerable amount of ²⁴¹Pu appeared in the surface layers of sediments and came from the Chernobyl accident. The Vistula and the Odra River were significant sources of plutonium in the southern Baltic Sea. Annually in 2002 and 2003, the Vistula River enriched its estuary in 10.3 MBq ²³⁸Pu, 89.0 MBq ^239+240Pu and 1.65 GBq of ²⁴¹Pu. The annual inflow of ²³⁸Pu, ^239+240Pu, and ²⁴¹Pu with the Odra River in 2002 and 2003 to the Pomeranian Bay was 9.51 MBq, 45.86 MBq and 0.62 GBq, respectively. The total ^239+240Pu activity deposited in the Gulf of Gdansk and the Gdansk Basin sediments was estimated at 1.18 TBq and 3.77 TBq. Based on the calculations and data available in the literature, the sediments of both regions were highly enr iched with plutonium - the sediments of the Gulf of Gdansk and the Gdansk Basin contained 6.4% and 22.0% of ^239+240Pu deposited in whole Baltic Sea sediments, whereas their areas constituted only 1.2% and 4.4% of its total area.