Assessment of radionuclides and heavy metals in marine sediments along the Upper Gulf of Thailand

International Nuclear Science and Technology Conference 2014

Khuntong, S.^1 ; Phaophang, C.^2 ; Sudprasert, W.^3

Faculty of Science at Si Racha, Kasetsart University Si Racha Campus, 199 Sukhumvit Rd., Si Racha, Chonburi

20230, Thailand^1

Radioisotope Center, Thailand Institute of Nuclear Technology, Vibhavadi Rangsit Rd., Chatuchak, Bangkok

10900, Thailand^2

Department of Applied Radiation and Isotopes, Faculty of Science, Kasetsart University, Ngam Wong Wan Rd., Chatuchak, Bangkok

10900, Thailand^3

关键词: Artificial radionuclides;    Effective dose rate;    External hazard index;    Gamma spectrometers;    Naturally-occurring radionuclides;    Organic matter content;    Radium equivalent activity;    Statistical evaluation;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/611/1/012023/pdf
DOI  :  10.1088/1742-6596/611/1/012023

来源: IOP

【 摘 要 】

Due to the Fukushima Daiichi nuclear disaster in 2011 and the development of nuclear power plant in neighboring countries such as Vietnam in the near future, radionuclide assessment in marine sediment during 2010 - 2011 may be useful as background levels for radiation protection in Thailand. Marine sediments (10 samples) were collected approximately 1 km away from the coastline along Chonburi to Pattaya, Chonburi Province. The sediments were ground and sieved through 2-mm test sieve after air drying. Radionuclides were measured with a gamma spectrometer equipped with a well-calibrated HPGe detector. The samples were prepared in the same geometry as the reference material. The optimal counting time was 60,000 - 80,000 s for statistical evaluation and uncertainties. No contamination of137Cs as an artificial radionuclide was found. Naturally-occurring radionuclides including238U,232Th and40K were found. The mean specific activities of238U,232Th and40K were 44 ± 10, 59 ± 17 and 463 ± 94 Bq/kg in the rainy season (2010); 41 ± 6, 50 ± 9 and 484 ± 83 Bq/kg in the winter (2010), and 39 ± 6, 41 ± 7 and 472 ± 81 Bq/kg in the summer (2011), respectively. The mean specific activities were higher than the values in the UNSCEAR report of 35, 30 and 400 Bq/kg for238U,232Th and40K, respectively. From the measured specific activities, the absorbed dose rate, radium equivalent activity, external hazard index and annual external effective dose rate were calculated in order to assess the health risk. No radiation hazards related to the radioactivity in the sediment were expected. The accumulation of radionuclides varied with the particle size and the organic matter content in the sediment. The accumulation of heavy metals showed similar results to that of the radionuclides in the sediment.