Isotopes of polonium (210Po) and uranium (234U and 238U) in the industrialised area of Wilinka (North Poland)

Phosphogypsum is very much enriched in natural polonium 210Po, while the uranium radionuclides (234U and 238U) tend to be in waters around waste dumps. The migration and distribution of uranium and polonium radionuclides in analysed water samples are not uniform. The amounts of uranium isotopes in a retention reservoir around the waste dump are 100 times higher than in typical natural river waters. The concentration of uranium in surface water samples collected near Wilinka (North Poland) ranged widely between 0.05 +/- 0.02 and 430 +/- 5 mu g L-1. In phosphogypsum samples, uranium concentrations varied in the range of 4.03 +/- 0.08 and 0.65 +/- 0.05 mg kg-1 in samples collected in 1997 and 2007, respectively. We observed that the activity ratio 234U/238U is approximately about one in the phosphogypsum (0.90 +/- 0.06 and 0.97 +/- 0.03) and in the water of the immediate surroundings of waste heap (1.00 +/- 0.06 and 1.07 +/- 0.05), while in surface river water from Martwa Wisa River is higher than one (1.10 +/- 0.07 and 1.16 +/- 0.13). The phosphogypsum samples contain much higher 210Po activity in comparison with uranium radionuclides. The concentration of 210Po in phosphogypsum samples is similar or slightly higher in 1997 and 2007 (600 +/- 10 and 700 +/- 10 Bq kg-1, respectively). Finally, the principal sources of 210Po, 234U, 238U radionuclides in the Wilinka area waste dump are phosphorites and phosphogypsum, produced by Phosphoric Fertilisers Industry of Gdansk.