Radioprotection 2025, 60( 4), 360 – 369 © J. Seo et al., Published by EDP Sciences 2025 https:// doi. org / 10.1051 / radiopro / 2025017
Available online at: www. radioprotection. org
ARTICLE
Distribution of 137 Cs in fishes from the seas surrounding Korea: its bioaccumulation and annual effective dose
Junhyeong Seo 1, Huisu Lee 1, 2, Jaeeun Lee 1, 2, Hyunmi Lee 1, Suk-Hyun Kim 1 and Intae Kim 1, 2,*
1 Marine Environmental Research Department, Korea Institute of Ocean Science and Technology( KIOST), Busan 49111, South Korea. 2 Department of Ocean Science, University of Science and Technology( UST), Daejeon 34113, South Korea.
Received: 3 February 2025 / Accepted: 27 May 2025
Abstract – The distribution of artificial radionuclide 137 Cs in fish from the seas surrounding the Korean Peninsula was investigated to estimate the bioaccumulation and annual effective dose rate according to size. The activity of 137 Cs in the muscles of seven fish species( armored weaselfish, croaker, flounder, hairtail, catfish, conger, and mackerel) was in the range of 50 – 269 mBq kg �1, which was similar to that observed in Korean Seas between 2017 and 2021(< 22 to 288 mBq kg �1). The results showed no particular enrichment pattern based on the fish body size. The activity of 137 Cs in dissected parts, such as the skin, inner organs, gills, and gonads, was in the range of 29 – 311 mBq kg �1, and the parts where 137 Cs was most enriched varied among fish species and growth stages. The annual effective dose rate of 137 Cs provided by the seafood consumption of these fish in South Korea was estimated to be 0.10 – 4.81 10 �6 mSv y �1, which is insignificant relative to that of natural radionuclides such as 210 Po. Thus, these results indicated that annual dose rate by the 137 Cs dose not have a noticeable impact on marine organisms, however, continuous monitoring with various species of fish is necessary to evaluate possible future nuclear power plant accidents.
Keywords: Cs-137 / fishes / Korean Seas / bioaccumulation / annual effective dose
1 Introduction
Cesium-137( 137 Cs; t 1 / 2 = 30.17 yrs) is mainly produced through nuclear fission via the decay of uranium-235( 235 U) from nuclear power plants( NPPs) and nuclear weapons. In marine environments, 137 Cs has been used as a tracer to estimate water residence time( Hirose et al., 1992; Zhang et al., 2019) and identify the long-range transport of water masses( Aoyama et al., 2008; Sanchez-Cabeza et al., 2011) because of its high solubility. In addition, 137 Cs is widely used to trace sedimentation rates based on its depositional history and substantial input signals to marine sediments( Alvarez-Iglesias et al., 2007; Huh and Su, 1999). Therefore, the distribution of 137 Cs can provide useful information for understanding
various oceanic processes.
Although 137 Cs is a good tracer in the marine environment, it is considered a radionuclide harmful to biota because it has a relatively long half-life and a high gamma energy level( 662 keV). Additionally, 137 Cs can be assimilated and accumulated alongside potassium in the human body because of its chemical similarity to potassium, an essential alkaline
* Corresponding author: ikim @ kiost. ac. kr element in the human body( Cao et al., 2022). The biological half-life of 137 Cs in the human body, defined as the time required to eliminate 50 % of its initial activity, ranges from 30 to 165 days, depending on gender and age( Cahill and Wheeler, 1968; Uchiyama, 1978). Consequently, the determination of 137 Cs in marine products is important because it can be easily consumed by living organisms( Ashraf et al., 2014; Iwamoto and Minoda, 2018) and accumulate at trophic levels( Heldal et al., 2003; Sundbom et al., 2003).
South Korea began operating its first NPP in 1977 and has become one of the world’ s leading producers of nuclear energy. Presently, South Korea had 25 NPPs in operation, generating approximately 24 GWe of electricity and accounting for more than 30 % of the annual domestic electricity consumption( Rand and Siegel, 2020). Geographically, the Korean Peninsula is surrounded by China, Japan, and Russia, all of which are highly dependent on nuclear power. After the Fukushima Daiichi NPP( FDNPP) accident caused by the Great East Japan Earthquake on March 11, 2011, higher radiocesium( 134 Cs and 137 Cs) concentrations were introduced into the waters close to the marginal seas of the North Pacific( Hirose, 2016; Takata and Kumamoto, 2022). Approximately, 15 – 18 PBq of 137 Cs is released into the North Pacific and eventually transported to North America and the Arctic Ocean
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