title: Initial flux of sediment-associated radiocesium to the ocean from the largest river impacted by Fukushima Daiichi Nuclear Power Plant.
abstract: This study aimed to quantify the flux of radiocesium in the Abukuma Basin (5,172 km(2)), the largest river system affected by fallout from the Fukushima Daiichi Nuclear Power Plant (FDNPP) event. In the period from 10 August 2011 to 11 May 2012 an estimated 84 to 92% of the total radiocesium transported in the basin's fluvial system was carried in particulate form. During this monitoring period Typhoon Roke (September 2011) was observed to induce a significant and temporally punctuated redistribution of radiocesium. The storm-mobilised radiocesium was an estimated 6.18 Terabecquerels corresponding to 61.4% of the total load delivered to the coastal zone during the observation period. The total flux of radiocesium into the Pacific Ocean estimated at the outlet station (basin area 5,172 km(2)) was 5.34 TBq for (137)Cs, and 4.74 TBq for (134)Cs, corresponding to 1.13% of the total estimated radiocesium fallout over the basin catchment (890 TBq). This was equivalent to the estimated amount of direct leakage from FDNPP to the ocean during June 2011 to September 2012 of 17 TBq and the Level 3 Scale Leakage on 21 August 2013 (24 TBq).
authors.affiliation: 1] Graduate School of Advanced Integrated Studies in Human Survivability, Kyoto University [2] Application Laboratory, Japan Agency for Marine-Earth Science and Technology.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Yamashiki
authors.affiliation: Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Onda
authors.affiliation: School of Environmental Sciences, University of Liverpool, UK.
authors.forename: Hugh G
authors.initials: HG
authors.lastname: Smith
authors.affiliation: School of Geography, Earth and Environmental Sciences, Plymouth University, UK.
authors.forename: William H
authors.initials: WH
authors.lastname: Blake
authors.affiliation: Institute of Symbiotic Science and Science, Tokyo University of Agriculture and Technology.
authors.forename: Taeko
authors.initials: T
authors.lastname: Wakahara
authors.affiliation: Meteorological Research Institute.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Igarashi
authors.affiliation: Yachiyo Engineering Co. Ltd.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Matsuura
authors.affiliation: Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yoshimura