Promieniotwórczość naturalna wód źródlanych uzdrowisk południowej Polski

Abstract

The publication deals with the occurrence of 238U- and 232Th-series radionuclides in natural groundwater from the areas of the Polish parts of the Sudety and Karpaty Zewnętrzne Mountains so as to evaluate the annual and long-term effective doses caused by these radionuclides in drinking water. In order to be able to reduce radiation exposure and avoid high doses, it is important to examine the activity levels of natural radionuclides in groundwater. The activity concentrations of radon (222Rn), radium (226,228Ra) and also uranium (234,235,238U) in one chosen region, Świeradów — Czerniawa health resort, were repeatedly measured in 154 intakes from 24 Sudety health resorts and 5 Karpaty Zewnętrzne health resorts. On the basis of the results, the correlations between investigated radionuclides were studied and the radiation exposure from drinking water to inhabitants and tourists was evaluated. In order to obtain accurate results and correct estimates of effective doses, particular attention was paid to the sampling of 222Rn and other radionuclides. Additionally, in Świeradów — Czerniawa health resort radium and uranium isotopes were studied in reservoir rocks infiltrated by underground water. The results allowed for the calculation of transmission coefficients in rock — to water environment. The results revealed that in Poland, the highest radioactivity in water may be found in the Sudety Mountains. The averaged activity concentrations of 222Rn observed ranged from 4,2 ±0,4 Bq/l to 1703 ±55 Bq/l. In the Karpaty Mountains, radon water was not found. The activity concentrations of 222Rn were up to 50 ±5 Bq/l. The activity concentrations of 226Ra isotope studied in the same intakes were from 0,010 ±0,001 to 1,013 ±0,070 Bq/l for the Sudety spring waters, and of 228Ra from 0,03 ±0,01 to 0,534 ±0,110 Bq/l. For the Karpaty Mts. the observed activity concentrations of 226Ra were lower, from 0,010 ±0,001 to 0,49 ±0,14 Bq/l, and for 228Ra from 0,018 ±0,004 to 0,40 ±0,24 Bq/l. The activity concentrations of 234,235,238U isotopes studied in 20 intakes in the Świeradów — Czerniawa region were most frequently one magnitude lower than the 228Ra concentrations. A new method using U/Ra-discs produced by Sarad company was examined for the easier and less expensive determination of 234U and 238U simultaneously with 226Ra. Preliminary results show that the method may be used for low — and medium — mineralized water. In Poland, there is a population of people who permanently use natural spring water from private intakes for daily drinking and household requirements. This group may receive nearly half (25,6 mS/70y) of the collective long-term effective dose due to only radium isotopes presence in drinking water. It should be noted that other radionuclides may also contribute to this dose. The equivalent doses on bone surface, due to radium intake with drinking water, are one magnitude higher. This work constitutes the first complex study of the natural radioactivity in underground water environment in the Polish mountains.