Contribution of 137Cs-enriched particles to radiocesium concentrations in seafloor sediment: Reconnaissance experiment.

Takahito Ikenoue,Nobuyoshi Ishii,Masashi Kusakabe,Hyoe Takata,Tim A. Mousseau

doi:10.1371/journal.pone.0204289

Abstract

Autoradiography was used to detect 137Cs-enriched particles in sediment samples. The contributions of 137Cs-enriched particles to 137Cs concentrations in sediment samples ranged from 9% to 64%. These experiments revealed that the variability of 137Cs concentrations was due mainly to the heterogeneous distribution of 137Cs-enriched particles in the samples. Therefore, the heterogeneous distribution of 137Cs-enriched particles is probably one of the main factors responsible for the temporal and spatial variations of 137Cs concentrations in sediment samples.

Highlights

The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident on 11 March 2011 resulted in the release of large amounts of anthropogenic radionuclides into the ocean and atmosphere and onto the land [1, 2]
Radioactivity has been monitored in seafloor sediments off Fukushima and nearby prefectures regularly as a part of projects commissioned by the Japanese Ministry of Education, Culture, Sports, Science and Technology (May 2011 to March 2013) and the Secretariat of the Nuclear Regulation Authority (April 2013 to present)
The 137Cs concentration in surface sediments generally increased with time after the FDNPP accident until the fall of 2011 [4] and began decreasing at variable rates [5]

Summary

Introduction

The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident on 11 March 2011 resulted in the release of large amounts of anthropogenic radionuclides into the ocean and atmosphere and onto the land [1, 2]. Radiocesium-bearing microparticles (CsMPs) have been found since the FDNPP accident in a variety of samples, including aerosols, soil, river water, forest leaves, vegetables, and oceanic zooplankton [7,8,9,10,11,12,13,14,15,16]. It is possible that the variability of radiocesium concentrations in seafloor sediments is due to the presence of heterogeneously distributed radioactive particles. We used an imaging plate for selected samples to evaluate the impact of radioactive particles on radiocesium concentrations in seafloor sediments. We report the heterogeneity of 137Cs concentrations in sediments due to the CsEPs

Material and methods

Results and discussion

17. Marine Ecology Research Institute