The inflow of 234U and 238U from the River Odra drainage basin to the Baltic Sea

In this study the activity of uranium isotopes 234U and 238U in Odra river water samples, collected from October 2003 to July 2004, was measured using alpha spectrometry. The uranium concentrations were different in each of the seasons analysed; the lowest values were recorded in summer. In all seasons, uranium concentrations were the highest in Bystrzyca river waters (from 27.81±0.29 Bq m−3 of 234U and 17.82±0.23 Bq m−3 of 238U in spring to 194.76±3.43 Bq m−3 of 234U and 134.88 ± 2.85 Bq m−3 of 238U in summer). The lowest concentrations were noted in the Mała Panew (from 1.33±0.02 Bq m−3 of 234U and 1.06±0.02 Bq m−3 of 238U in spring to 3.52 ± 0.05 Bq m−3 of 234U and 2.59 ± 0.04 Bq m−3 of 238U in autumn). The uranium radionuclides 234U and 238U in the water samples were not in radioactive equilibrium. The 234U/238U activity ratios were the highest in Odra water samples collected at Głogów (1.84 in autumn), and the lowest in water from the Noteć (1.03 in winter and spring). The 234U/238U activity ratio decreases along the main stream of the Odra, owing to changes in the salinity of the river’s waters. Annually, 8.19 tons of uranium (126.29 GBq of 234U and 100.80 GBq of 238U) flow into the Szczecin Lagoon with Odra river waters.