量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Accidental leakage of radionuclides from the Fukushima Nuclear Power Plant (FNPP1) took place in the aftermath of the catastrophic tsunamis associated with the Great East Japan Earthquake that occurred on March 11, 2011. Significant amount of radionuclides released into the atmosphere were reportedly transported and deposited on land located near FNPP1. The Niida River, Fukushima, Japan, has been recognized as a terrestrial source of highly contaminated suspended radiocesium adhering to sediment particles in the ocean through the river mouth as a result of hydrological processes.
Particularly, we investigated the storm and subsequent floods associated with Typhoon 201326 (Wipha) that passed off the Fukushima coast in October 2013, and subsequently promoted precipitation to a considerable extent and associated riverine freshwater discharge along with sediment outfluxes to the ocean. Using in situ bed sediment core data obtained from regions near the river mouth, we conducted a quantitative assessment of the accumulation and erosion of the sediments and explored the resultant suspended radiocesium distribution around the river mouth and nearshore areas along the Fukushima coast. We identified three major accumulative areas, near the river mouth within an area < 1 km, around the breakwaters in the north of the river mouth, and along the southern coastal area, while offshore and northward transports were minor. The present study clearly exhibits substantial retention of the land-derived radiocesium adhered to the sediments in the coastal areas, leading to possible long-term influences on the surrounding marine environment.
A storm-induced flood and associated nearshore dispersal of the river-derived suspended 137Cs
