title: Occurrence and partition ratios of radiocesium in an urban river during dry and wet weather after the 2011 nuclear accident in Fukushima.
abstract: After the 2011 nuclear accident in Fukushima, radiocesium was released from the Fukushima Dai-ichi Nuclear Power Plant and contaminated waters in urban areas near Tokyo. By intensive field monitoring during 3 years, this study investigated the temporal trends and the occurrence of radiocesium during dry and wet weather, and analyzed the variations in radiocesium during rainfall events and factors controlling them. Concentrations of particulate radiocesium decreased rapidly from May 2012 to March 2013 and reached an equilibrium in 2014. Concentrations of particulate (137)Cs during wet weather were almost double those during dry weather in the same period. In contrast to the small variations in (137)Cs concentrations in the particulate phase on a suspended solids (SS) weight basis during events, those in the dissolved phase on a liquid-volume basis fluctuated greatly, resulting in variations in the partition coefficient (apparent Kd). The apparent Kd of (137)Cs during wet weather ranged from 30,000 to 150,000 L kg(-1) and showed a significant negative correlation with SS concentrations during wet weather. Specific surface area in solids contributed to the variations in apparent Kd.
authors: Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo, 153-8505, Japan; Department of Health Risk Communication, School of Medicine, Fukushima Medical University, 1 Hikarigaoka, Fukushima City, 960-1295, Japan. Electronic address: michio@fmu.ac.jp.
authors: Michio
authors: M
authors: Murakami
authors: Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
authors: Nao
authors: N
authors: Shibayama
authors: Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
authors: Keisuke
authors: K
authors: Sueki
authors: Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo, 153-8505, Japan.
authors: Goro
authors: G
authors: Mouri
authors: Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8563, Japan.
authors: Haechong
authors: H
authors: O
authors: Faculty of Arts and Sciences Programs in English at Komaba (PEAK), The International Program on Environmental Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo, 153-8902, Japan.
authors: Mihiro
authors: M
authors: Nomura
authors: Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8563, Japan.
authors: Yukio
authors: Y
authors: Koibuchi
authors: Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo, 153-8505, Japan.
authors: Taikan
authors: T
authors: Oki
mesh_terms: D002588:Cesium Radioisotopes / Q000032:analysis*; D062406:Fukushima Nuclear Accident; D005843:Geography; D007700:Kinetics; D052638:Particulate Matter / Q000032:analysis; D045483:Rivers / Q000737:chemistry*; D013997:Time Factors; D014041:Tokyo; D014875:Water Pollutants, Radioactive / Q000032:analysis*; D014887:Weather
chemical_list: D002588:Cesium Radioisotopes; D052638:Particulate Matter; D014875:Water Pollutants, Radioactive
keywords: Coefficient of partition; Radionuclides; Rainfall; Specific surface areas; Temporal trend; Urban areas