Assessment of Natural and Anthropogenic Radioactivity of the Princes’ Islands in the Sea of Marmara

Abstract

In this study, the activity concentrations of naturally occurring 238U, 232Th and 40K and anthropogenic 137Cs radionuclides were measured for 56 soil and beach sand samples collected from the Princes’ Islands (Istanbul) in the Sea of Marmara, using a gamma-ray spectrometer. In each case, the outdoor gamma-ray dose rates in air were measured at the coordinates where the samples were collected, using a portable gamma-ray detector. In addition, the 210Po specific activity concentrations were measured for 13 different types of fish and 3 black mussel samples that are consumed in the region, using an alpha spectrometer. The mean activity concentrations of natural 238U, 232Th and 40K and artificial 137Cs radionuclides were calculated to be 33.8 ± 0.5 Bq kg−1, 19.3 ± 0.3 Bq kg−1, 429.5 ± 4.5 Bq kg−1 and 8.9 ± 0.1 Bq kg−1, respectively, in the soil and beach sand samples. Activity concentration contour maps of the Princes’ Islands (Istanbul) were constructed. The mean annual effective dose values for natural and artificial radioactive nuclide activity concentrations were determined to be 55.4 μSv y−1 and 1.2 μSv y−1, respectively. The average outdoor gamma-ray dose rate measured in the air was 0.68 mSv y−1. The mean activity concentrations of 210Po in the fish and mussel samples were measured to be 16.2 ± 1.9 Bq kg−1 and 516.1 ± 25.8 Bq kg−1. The average annual effective ingestion doses due to 210Po from the consumption of these seafoods were calculated to be 106.9 μSv y−1 and 619.4 μSv y−1, respectively. The results of this study were compared with the limits proposed by UNSCEAR, ICRP and the values obtained in other similar studies worldwide.