Differences in the Proportional Contributions of Particulate Radiocesium Sources under Base- and High-Flow River Conditions: A Case Study in the Central Region of Fukushima

Due to the Fukushima Daiichi Nuclear Power Plant accident in 2011, large amounts of radiocesium were deposited over forest ecosystems in the headwater regions of rivers in Fukushima Prefecture, Japan. There is considerable concern about whether the runoff from these regions will result in recontamin...

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Autores principales:	Hirotsugu Arai, Kazuki Fujita, Hirofumi Yoshita, Keisuke Taniguchi
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	suspended solids cesium-137 stable carbon isotope mixing model Hydraulic engineering TC1-978 Water supply for domestic and industrial purposes TD201-500
Acceso en línea:	https://doaj.org/article/96f5a36eb301414891cfa64be15249fd
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spelling	oai:doaj.org-article:96f5a36eb301414891cfa64be15249fd2021-11-11T19:54:50ZDifferences in the Proportional Contributions of Particulate Radiocesium Sources under Base- and High-Flow River Conditions: A Case Study in the Central Region of Fukushima10.3390/w132130212073-4441https://doaj.org/article/96f5a36eb301414891cfa64be15249fd2021-10-01T00:00:00Zhttps://www.mdpi.com/2073-4441/13/21/3021https://doaj.org/toc/2073-4441Due to the Fukushima Daiichi Nuclear Power Plant accident in 2011, large amounts of radiocesium were deposited over forest ecosystems in the headwater regions of rivers in Fukushima Prefecture, Japan. There is considerable concern about whether the runoff from these regions will result in recontamination of lower-lying areas further downstream after heavy rainfall events and typhoons. This study examined the sources and levels of cesium-137 (<sup>137</sup>Cs), the most abundant radioisotope in river sediments, in total suspended solids (TSS) in river water. In addition, changes in the predominant source of TSS associated with changes in river conditions were investigated. The properties of total organic carbon (TOC) in TSS (concentrations and isotopic compositions) were also measured to identify differences among sources. The results showed reductions in <sup>137</sup>Cs and TOC properties in TSS when the river conditions changed from base flows to high flows, indicating the existence of a dilution effect through the addition of mineral particles from extraneous sources. Simulation results obtained using a mixing model suggested that forest soils are the primary source of TSS regardless of river conditions, but that the relative contribution of TSS from forest soils was decreased under high-flow conditions. Meanwhile, the relative contributions of both riverbank soil and river sediments were increased under high-flow conditions. Due to the low <sup>137</sup>Cs concentrations in riverbank soils and river sediments, it is unlikely that heavy rainfall events will cause serious recontamination of areas downstream in the study area.Hirotsugu AraiKazuki FujitaHirofumi YoshitaKeisuke TaniguchiMDPI AGarticlesuspended solidscesium-137stable carbon isotopemixing modelHydraulic engineeringTC1-978Water supply for domestic and industrial purposesTD201-500ENWater, Vol 13, Iss 3021, p 3021 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	suspended solids cesium-137 stable carbon isotope mixing model Hydraulic engineering TC1-978 Water supply for domestic and industrial purposes TD201-500
spellingShingle	suspended solids cesium-137 stable carbon isotope mixing model Hydraulic engineering TC1-978 Water supply for domestic and industrial purposes TD201-500 Hirotsugu Arai Kazuki Fujita Hirofumi Yoshita Keisuke Taniguchi Differences in the Proportional Contributions of Particulate Radiocesium Sources under Base- and High-Flow River Conditions: A Case Study in the Central Region of Fukushima
description	Due to the Fukushima Daiichi Nuclear Power Plant accident in 2011, large amounts of radiocesium were deposited over forest ecosystems in the headwater regions of rivers in Fukushima Prefecture, Japan. There is considerable concern about whether the runoff from these regions will result in recontamination of lower-lying areas further downstream after heavy rainfall events and typhoons. This study examined the sources and levels of cesium-137 (<sup>137</sup>Cs), the most abundant radioisotope in river sediments, in total suspended solids (TSS) in river water. In addition, changes in the predominant source of TSS associated with changes in river conditions were investigated. The properties of total organic carbon (TOC) in TSS (concentrations and isotopic compositions) were also measured to identify differences among sources. The results showed reductions in <sup>137</sup>Cs and TOC properties in TSS when the river conditions changed from base flows to high flows, indicating the existence of a dilution effect through the addition of mineral particles from extraneous sources. Simulation results obtained using a mixing model suggested that forest soils are the primary source of TSS regardless of river conditions, but that the relative contribution of TSS from forest soils was decreased under high-flow conditions. Meanwhile, the relative contributions of both riverbank soil and river sediments were increased under high-flow conditions. Due to the low <sup>137</sup>Cs concentrations in riverbank soils and river sediments, it is unlikely that heavy rainfall events will cause serious recontamination of areas downstream in the study area.
format	article
author	Hirotsugu Arai Kazuki Fujita Hirofumi Yoshita Keisuke Taniguchi
author_facet	Hirotsugu Arai Kazuki Fujita Hirofumi Yoshita Keisuke Taniguchi
author_sort	Hirotsugu Arai
title	Differences in the Proportional Contributions of Particulate Radiocesium Sources under Base- and High-Flow River Conditions: A Case Study in the Central Region of Fukushima
title_short	Differences in the Proportional Contributions of Particulate Radiocesium Sources under Base- and High-Flow River Conditions: A Case Study in the Central Region of Fukushima
title_full	Differences in the Proportional Contributions of Particulate Radiocesium Sources under Base- and High-Flow River Conditions: A Case Study in the Central Region of Fukushima
title_fullStr	Differences in the Proportional Contributions of Particulate Radiocesium Sources under Base- and High-Flow River Conditions: A Case Study in the Central Region of Fukushima
title_full_unstemmed	Differences in the Proportional Contributions of Particulate Radiocesium Sources under Base- and High-Flow River Conditions: A Case Study in the Central Region of Fukushima
title_sort	differences in the proportional contributions of particulate radiocesium sources under base- and high-flow river conditions: a case study in the central region of fukushima
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/96f5a36eb301414891cfa64be15249fd
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Differences in the Proportional Contributions of Particulate Radiocesium Sources under Base- and High-Flow River Conditions: A Case Study in the Central Region of Fukushima

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