Seasonal determination of anthropogenic 137 Cs specific activities, radiological risks, and elemental analysis in the sediments of Darbandikhan Lake in Kurdistan, Iraq

Throughout the four seasons, 100 sediment samples (25 each season) were collected from Darbandikhan Lake. The specific activity of the artificial radioisotope 137Cs was measured using a HPGe detector. The seasonally measured average activity concentration of 137Cs radionuclide in sediment samples were (1.656 ± 0.055, 1.634 ± 0.055, 2.321 ± 0.061 and 1.66 ± 0.056) Bq kg−1 in spring, summer, autumn and winter, respectively. These values are significantly lower than the recommended threshold of 10 Bq kg−1 stated by UNCEAR (2000). Small variations in specific activity of this anthropogenic radionuclide were seen, ranging from below the minimum detection activity to a certain value during each season, except autumn in which some fluctuations have been observed in compare to other seasons. The ANOVA test shows a low F-statistic (0.69) and a high p-value (0.56), revealing a non-significant variation in 137Cs sediment activity between seasons. The radiological parameters, including: absorbed dose, annual effective dose, and cancer risk associated with the activity of 137Cs, were evaluated for the studied sediment samples and all values are significantly below the recommended limits. The statistical analysis revealed that 137Cs shows a strong positive correlation with Fe, Mn, and Ti. Conversely, Ca, P, Mg and Si display a weak negative correlation with 137Cs. The results show that the sediments of Darbandikhan Lake are safe from radiological contamination linked to 137Cs pollution. These findings establish baseline data for tracking any future changes in 137Cs levels.