Dynamics of Radioactive Cesium in Coastal Area Linked with River Discharge

• Published in: Journal of coastal research Vol. 114; no. sp1; pp. 315 - 319
• Main Authors: Misonou, Toshiharu, Tsuruta, Tadahiko, Shiribiki, Takehiko, Nakanishi, Takahiro, Nagao, Seiya, Ochiai, Shinya, Sanada, Yukihisa
• Format: Journal Article
• Language: English
• Published: Fort Lauderdale Coastal Education and Research Foundation 06.10.2021; Allen Press Publishing; Allen Press Inc
• Subjects: Caesium; Caesium 137; Carbon isotope ratio; Carbon isotopes; Cesium; Cesium 137; Cesium isotopes; Coastal area; Coastal inlets; Coastal management; COASTAL POLLUTION; Coastal research; Coastal zone; Coasts; Dynamics; Hurricanes; Inflow; Isotope ratios; Measuring instruments; Mooring systems; Particulate flux; Rain; River discharge; Rivers; Sediment; Sediment traps; Sinking; sinking particle; stable carbon isotope ratio; Water depth; Water discharge; Water quality
• ISSN: 0749-0208; 1551-5036
• DOI: 10.2112/JCR-SI114-064.1

Misonou, T.; Tsuruta, T.; Shiribiki, T.; Nakanishi, T.; Nagao, S.; Ochiai, S., and Sanada, Y., 2021. Dynamics of radioactive cesium in coastal area linked with river discharge. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 315–319. Coconut Creek (Florida), ISSN 0749-0208. For understanding the dynamics of future radioactive cesium (Cs) and its distribution in the coastal area of Fukushima Prefecture, radioactive Cs supply from river discharge must be evaluated. Particulate radioactive Cs supplied by floods could significantly affect the coastal area. Therefore, the effect of particulate radioactive Cs supplied from the river was clarified by installing mooring systems (sediment traps and water quality meters) at four points (water depths of St.1: 10 m, St.2: 27 m, St.3: 30 m, and St.4: 60 m) in the coastal area of Fukushima Prefecture from October 22 to 28, 2019. During the observation period, a large typhoon (Bualoi) accompanied by torrential rain struck Fukushima Prefecture. The 137Cs concentrations of the sinking particles collected by the sediment trap at the observation point installed in front of the river (St.1) were collected immediately after typhoon Bualoi (October 25) and were approximately three times higher than before the typhoon. However, the 137Cs concentration of the sinking particles collected two days after the typhoon (October 27) was almost the same as before the typhoon. Local increases in 137Cs were not observed at other stations. The stable carbon isotope ratio (δ13C) of the sinking particles during the typhoon was approximately –30 to –26‰ at the measurement points installed in front of the Ukedo, Ohta, and Kuma Rivers (St.1, St.2, and St.3). It was assumed that there was an influence of inflow from the river on St.1, St.2, and St.3 after precipitation. The impact of rivers on coastal areas during torrential rain is extremely limited.