Atmospheric deposition and riverine load of (90)Sr and (137)Cs to the Gulf of Gdańsk (southern Baltic Sea) in the period 2005-2011.

In the period 2005-2011 total atmospheric fallout and the riverine input to the Gulf of Gdańsk was 1168.8 GBq of (90)Sr and 424.1 GBq (137)Cs. The major source of both radionuclides to the Gulf of Gdańsk is the Vistula river; its contribution reached 99.7% in the case of (90)Sr and 95.8% regarding (137)Cs. The atmospheric load of (137)Cs, 18.1 GBq, was nearly 4 times bigger than in the case of (90)Sr (3.75 GBq). In the period 2005-2010, the average annual atmospheric load were at the levels 2-3 GBq for (137)Cs and 0.4-0.6 GBq for (90)Sr, while in 2011, due to the Fukuchima Dai-ichi power plant break down, an increase of annual atmospheric loads was noted to 5.3 GBq of (137)Cs and to 0.87 GBq of (90)Sr. The additional loads did not have an increasing effect on the activity concentrations of (137)Cs and (90)Sr in seawater of the Gulf of Gdańsk, where mean activity concentrations in seawater were equal to 31.1 Bq m(-3) and 7.6 Bq m(-3) in the case of (137)Cs and (90)Sr respectively.