A preliminary study on the environmental monitoring, and estimation of the environmental dose in a high natural background radiation area of Ramsar, Iran.

Abstract

High natural background radiation areas (HNBRAs) worldwide contribute additional radiation doses to humans, plants, and land animals. Among these regions, Talesh Mahalleh in Ramsar, Iran, is notable for having the highest levels of natural background radiation in the world. This study aimed to assess the natural radioactivity in this region. The study was performed in three phases: (i) analyzing the activity concentrations of radioactive elements in samples of soil, water, and plants, collected from various parts of Talesh Mahalleh, by gamma spectroscopy using a high-purity germanium detector. (ii) Measurement of the environmental radiation doses in different locations of the high background area using thermoluminescence dosimetry (TLD), for 2 months. (iii) The environmental radiation monitoring using a calibrated survey meter. The concentrations of natural radioactive materials, like Ra-226, Th-232, and K-40 activity were measured in soil, water, and plants. Based on the results, the maximum concentration of Ra-226 in the soil samples prepared from Talesh Mahalleh was found to be 16 687 Bq/kg. The survey meter indicated the dose rates of 2.51 to 8.43 μSv/h in the high background area of Talesh Mahalleh, which is much higher than the average natural background in the world. The results of TLD are in consistent with the online environmental monitoring. This preliminary research highlights the critical need for further studies on the measurement of external and internal dosimetry for terrestrial animals of this HNBRA.