Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa-Ku, Tokyo, 116-8551, Japan.
Institute for Radiological Sciences, National Institutes for Quantum Science and Technology (QST), Inage-Ku, Chiba, 263-8555, Japan.
Environ Monit Assess. 2024 Mar 1;196(3):330. doi: 10.1007/s10661-024-12456-x.
The Kanyakumari coast is known to be a high background natural radiation area due to the placer deposits of heavy minerals such as ilmenite, monazite, and rutile. The Kanyakumari river sediments that could be the source of the elevated amounts of natural radionuclides in the coastal sands have been studied in this paper. The activity concentrations of primordial radionuclides Ra, Th, and K were determined using high-purity germanium (HPGe) gamma-ray spectrometry. The mean activity concentrations of Ra, Th, and K were found to be 75 Bq kg, 565 Bq kg, and 360 Bq kg, respectively. The mean absorbed dose rate was 395 nGy h. Radiological hazard parameters were studied and compared with the world average values. The contribution of Th to the total dose rate was found to be higher than that of the two other radionuclides. The high mean ratio of Th/Ra suggested an enrichment of Th and the occurrence of Ra leaching due to an oxidizing environment. Principal component analysis (PCA) was carried out for the radionuclides in order to discriminate the source of the sediments. This study provides new insights into the distribution of natural radionuclides in sediments of rivers and streams.
楠奇库马里海岸由于重矿物（如钛铁矿、独居石和金红石）的砂矿沉积而被认为是一个高天然本底辐射区。本文研究了可能是海岸砂中高含量天然放射性核素来源的楠奇库马里河沉积物。使用高纯锗（HPGe）伽马能谱法测定了原生放射性核素 Ra、Th 和 K 的活度浓度。发现 Ra、Th 和 K 的平均活度浓度分别为 75 Bq kg、565 Bq kg 和 360 Bq kg。平均吸收剂量率为 395 nGy h。研究了放射性危害参数，并与世界平均值进行了比较。发现 Th 对总剂量率的贡献高于其他两个放射性核素。高的 Th/Ra 平均值表明 Th 的富集和由于氧化环境导致的 Ra 浸出的发生。为了区分沉积物的来源，对放射性核素进行了主成分分析（PCA）。本研究为河流和溪流沉积物中天然放射性核素的分布提供了新的见解。
