title: Behaviour of radiocaesium in coastal rivers of the Fukushima Prefecture (Japan) during conditions of low flow and low turbidity--Insight on the possible role of small particles and detrital organic compounds.
abstract: To investigate riverine transfers from contaminated soils of the Fukushima Prefecture in Japan to the marine environment, suspended sediments, filtered water, sediments and detrital organic macro debris deposited onto river beds were collected in November 2013 within small coastal rivers during conditions of low flow rates and low turbidity. River waters were directly filtered on the field and high efficiency well-type Ge detectors were used to analyse radiocaesium concentrations in very small quantities of suspended particles and filtered water (a few mg to a few g). For such base-flow conditions, our results show that the watersheds studied present similar hydro-sedimentary behaviours at their outlets and that the exports of dissolved and particulate radiocaesium are comparable. Moreover, the contribution of these rivers to the instantaneous export of radiocaesium to the ocean is similar to that of the Abukuma River. Our preliminary results indicate that, in the estuaries, radiocaesium concentrations in suspended sediments would be reduced by more than 80%, while radiocaesium concentration in filtered waters would be maintained. Significant correlations between radiocaesium concentrations and radiocaesium inventories in the soils of the catchments indicate that there was at that time little intra and inter-watershed variability in the transfer processes of radiocaesium from lands to rivers at this regional scale. The apparent liquid-solid partition coefficient (KD) values acquired for the lowest loads/finest particles complement the values acquired by using sediment traps and highlight the strong capacity of the smallest particles to transfer radiocaesium. Finally, but not least, our observations suggest that there could be a significant transfer of highly contaminated detrital biomass from forest litter to the downstream rivers in a rather conservative way.
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV, SESURE/LERCM, SERIS/LM2E, L2BT, STEME/LMRE, BP 3, 13115, Saint Paul Lez Durance, France. Electronic address: frederique.eyrolle-boyer@irsn.fr.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Eyrolle-Boyer
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV, SESURE/LERCM, SERIS/LM2E, L2BT, STEME/LMRE, BP 3, 13115, Saint Paul Lez Durance, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Boyer
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV, SESURE/LERCM, SERIS/LM2E, L2BT, STEME/LMRE, BP 3, 13115, Saint Paul Lez Durance, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Garcia-Sanchez
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV, SESURE/LERCM, SERIS/LM2E, L2BT, STEME/LMRE, BP 3, 13115, Saint Paul Lez Durance, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Métivier
authors.affiliation: Center for Research in Isotopes and Environmental Dynamics (CRIED), Tsukuba University, Tsukuba, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Onda
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV, SESURE/LERCM, SERIS/LM2E, L2BT, STEME/LMRE, BP 3, 13115, Saint Paul Lez Durance, France.
authors.forename: Anne
authors.initials: A
authors.lastname: De Vismes
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV, SESURE/LERCM, SERIS/LM2E, L2BT, STEME/LMRE, BP 3, 13115, Saint Paul Lez Durance, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Cagnat
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV, SESURE/LERCM, SERIS/LM2E, L2BT, STEME/LMRE, BP 3, 13115, Saint Paul Lez Durance, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Boulet
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV, SESURE/LERCM, SERIS/LM2E, L2BT, STEME/LMRE, BP 3, 13115, Saint Paul Lez Durance, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Cossonnet
mesh_terms: D002588:Cesium Radioisotopes / Q000032:analysis*; D062406:Fukushima Nuclear Accident; D019015:Geologic Sediments / Q000032:analysis*; D007564:Japan; D011834:Radiation Monitoring; D045483:Rivers / Q000737:chemistry*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D002588:Cesium Radioisotopes; D014875:Water Pollutants, Radioactive
keywords: Estuaries; Fukushima; KD; Litter; Organic compounds; Radiocaesium; Rivers; Suspended sediment