Investigation of U-235, Ra-226, Th-232, K-40, Cs-137, and heavy metal concentrations in Anzali international wetland using high-resolution gamma-ray spectrometry and atomic absorption spectroscopy

摘要

Measurements of natural radioactivity levels and heavy metals in sediment and soil samples of the Anzali international wetland were carried out by two HPGe-gamma ray spectrometry and atomic absorption spectroscopy techniques. The concentrations of U-235, Ra-226, Th-232, K-40, and Cs-137 in sediment samples ranged between 1.05 +/- 0.51-5.81 +/- 0.61, 18.06 +/- 0.63-33.36 +/- .0.34, 17.57 +/- 0.38-45.84 +/- 6.23, 371.88 +/- 6.36-652.28 +/- 11.60, and 0.43 +/- 0.06-63.35 +/- 0.94 Bq/kg, while in the soil samples they vary between 2.36-5.97, 22.71-38.37, 29.27-42.89, 472.66-533, and 1.05-9.60 Bq/kg for U-235, Ra-226, Th-232, K-40, and Cs-137, respectively. Present results are compared with the available literature data and also with the world average values. The radium equivalent activity was well below the defined limit of 370 Bq/kg. The external hazard indices were found to be less than 1, indicating a low dose. Heavy metal concentrations were found to decrease in order as Fe > Mn > Sr > Zn > Cu > Cr > Ni > Pb > Co > Cd. These measurements will serve as background reference levels for the Anzali wetland.