Natural radioactivity in various surface waters in İstanbul, Turkey

Gross- α and gross- β, activities of eight well and five tap water samples taken in İstanbul were determined. Ra 226, Rn 222, Pb 214, Bi 214, K 40, Cs 137 activity concentrations in four lake, four sea water, one snow and one rain water samples were also analyzed in order to determine their radioactivity. The results obtained showed that, in general, natural activities in drinking water samples did not exceed WHO and ITS guidelines. In sea and lake water, four samples were over WHO and TSI guidelines. Concentrations ranging from 0.007 to 0.04 Bq l −1 and from 0.02 to 0.1 Bq l −1 were observed for drinking water and the gross- α and gross- β activities, respectively. For all samples the gross- β activities were higher than the corresponding gross- α activities. In order to evaluate the annual effective dose equilavent of ingestion of these waters, a conservative dosimetric calculation was carried out using dose conversion factor suggested by the ICRP. An average annual effective dose equivalent of 0.84 μSv y −1 for Ra 226 was calculated.