Present status of ~(222)Rn in groundwater in Extremadura

摘要

Radon-222 was measured in groundwater sources of Extremadura (Spain), analyzing 350 samples from private and public springs, wells, and spas by liquid scintillation counting (LSC) and gamma spectrometry. The ~(222)Rn activity concentrations ranged from 0.24 to 1168 Bq L~(-1). The statistical analysis showed a log-normal distribution with a mean of (111 ± 7) Bq L~(-1) and a median of (36 ± 3) Bq L~(-1). A hydrogeological study revealed correlations between the activity concentration and the aquifer material's characteristics. A map of ~(222)Rn in groundwater was elaborated and compared with the natural gamma radiation map for this region. About 35% of the samples showed ~(222)Rn activity concentrations above the Euratom recommended limit of 100 Bq L~(-1). Three uranium series radionuclides (~(238)U, ~(234)U, and ~(226)Ra) were also assayed by alpha-particle spectrometry, estimating the annual effective dose due to the presence of these natural radionuclides in drinking water.