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Establishment and Application of Taiwan's First Marine Data Buoy for In Situ Automated Gamma Radioactivity Monitoring: A Case Study of Cesium-137 and Bismuth-214
Bo-Shian Wang 1*, Christos Tsabaris 2, Ke-Hsien Fu 1, Wen-Chang Yang 1, Sheng-Hsueh Chen 3, Mong-Hsien Shih 3, Chien-Ming Lee 3, Yi-Fang Lee 1, Kun-I Lin 1 and Kuo-Ching Jao 3
1National Academy of Marine Research (NAMR), Ocean Affairs Council, Taiwan
2Hellenic Centre for Marine Research (HCMR), Institute of Oceanography, Greece
3Coastal Ocean Monitoring Center (COMC), National Cheng Kung University, Taiwan
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Abstract:
To establish a technology for near-continuous and near-real-time monitoring of marine radioactivity and to enhance early warning of abnormal radioactivity in the ocean, we constructed a marine in situ automated gamma radioactivity monitoring buoy station off the northeastern coast of Yilan, Taiwan, in 2022. The data is transmitted via 4G and automatically converted into activity concentrations using an automatic alarm module that determines and issues threshold concentration alerts, thus establishing a comprehensive procedure for marine radioactivity alarms. Data reliability was ensured through the use of the naturally occurring nuclide 40K. During the monitoring period, from August to December 2021, activity concentrations of the anthropogenic nuclide 137Cs remained consistently below the instrumental detection limit. This observation provides conclusive evidence of the absence of safety concerns related to 137Cs contamination in the seawater off the coast of Yilan. Furthermore, the dose rates of naturally occurring nuclide 214Bi exhibited a correlation with precipitation, especially during rainfalls caused by typhoons passing through the buoy deployment area and the East Asian Monsoon in winter. However, for typhoon-induced precipitation events that did not traverse the study area, substantial amounts of 214Bi were generated, yet no significant relationship was observed between the rainfall amount and the corresponding 214Bi activity concentration. The underlying mechanism behind this preliminary observation requires further investigation.
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Keywords: Marine gamma radioactivity, cesium-137, bismuth-214, data buoy, automated monitoring.
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*Corresponding author; e-mail: bswang@namr.gov.tw
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©
2023
Marine Research , ISSN 2709-6629
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