title: Do forests represent a long-term source of contaminated particulate matter in the Fukushima Prefecture?
abstract: The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident resulted in radiocesium fallout contaminating coastal catchments of the Fukushima Prefecture. As the decontamination effort progresses, the potential downstream migration of radiocesium contaminated particulate matter from forests, which cover over 65% of the most contaminated region, requires investigation. Carbon and nitrogen elemental concentrations and stable isotope ratios are thus used to model the relative contributions of forest, cultivated and subsoil sources to deposited particulate matter in three contaminated coastal catchments. Samples were taken from the main identified sources: cultivated (n = 28), forest (n = 46), and subsoils (n = 25). Deposited particulate matter (n = 82) was sampled during four fieldwork campaigns from November 2012 to November 2014. A distribution modelling approach quantified relative source contributions with multiple combinations of element parameters (carbon only, nitrogen only, and four parameters) for two particle size fractions (<63 μm and <2 mm). Although there was significant particle size enrichment for the particulate matter parameters, these differences only resulted in a 6% (SD 3%) mean difference in relative source contributions. Further, the three different modelling approaches only resulted in a 4% (SD 3%) difference between relative source contributions. For each particulate matter sample, six models (i.e. <63 μm and <2 mm from the three modelling approaches) were used to incorporate a broader definition of potential uncertainty into model results. Forest sources were modelled to contribute 17% (SD 10%) of particulate matter indicating they present a long term potential source of radiocesium contaminated material in fallout impacted catchments. Subsoils contributed 45% (SD 26%) of particulate matter and cultivated sources contributed 38% (SD 19%). The reservoir of radiocesium in forested landscapes in the Fukushima region represents a potential long-term source of particulate contaminated matter that will require diligent management for the foreseeable future.
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL), Unité Mixte de Recherche 8212 (CEA/CNRS/UVSQ), Université Paris-Saclay, Centre de Recherche du CNRS - Bât, 12 - Avenue de la terrasse, 91 198 Gif-sur-Yvette, France. Electronic address: placeby@lsce.ipsl.fr.
authors.forename: J Patrick
authors.initials: JP
authors.lastname: Laceby
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, Institut d'Ecologie et des Sciences de l'Environnement de Paris (iEES), Case 120, 4 Place Jussieu, 75252 Paris Cedex 05, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Huon
authors.affiliation: Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Onda
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, Institut d'Ecologie et des Sciences de l'Environnement de Paris (iEES), Case 120, 4 Place Jussieu, 75252 Paris Cedex 05, France.
authors.forename: Veronique
authors.initials: V
authors.lastname: Vaury
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL), Unité Mixte de Recherche 8212 (CEA/CNRS/UVSQ), Université Paris-Saclay, Centre de Recherche du CNRS - Bât, 12 - Avenue de la terrasse, 91 198 Gif-sur-Yvette, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Evrard
mesh_terms: D002588:Cesium Radioisotopes / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods; D065928:Forests; D062406:Fukushima Nuclear Accident; D019015:Geologic Sediments / Q000032:analysis; D007564:Japan; D008962:Models, Theoretical; D009587:Nitrogen Isotopes / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis*; D011834:Radiation Monitoring; D012990:Soil Pollutants, Radioactive / Q000032:analysis; D014875:Water Pollutants, Radioactive / Q000032:analysis
chemical_list: D002588:Cesium Radioisotopes; D009587:Nitrogen Isotopes; D052638:Particulate Matter; D012990:Soil Pollutants, Radioactive; D014875:Water Pollutants, Radioactive
keywords: FDNPP; Japan; Organic matter; Sediment fingerprinting; Sediment tracing; Stable isotopes