A Numerical Study on Oceanic Dispersion and Sedimentation of Radioactive Cesium-137 from Fukushima Daiichi Nuclear Power Plant

Abstract

We discussed a numerical model for oceanic dispersion and sedimentation of radioactive cesium-137 (Cs-137) in shallow water regions to clarify migration behavior of Cs-137 from Fukushima Daiichi Nuclear Power Plant. Our model considered oceanic transport by three dimensional ocean current, adsorption with large particulate matter (LPM), sedimentation and resuspension. The simulation well reproduced the spatial characteristics of sea surface concentration and sediment surface concentration of Cs-137 off Miyagi, Fukushima, and Ibaraki Prefectures during May-December 2011. The simulated results indicated that the adsorption-sedimentation of Cs-137 significantly occurred during strong wind events because the large amount of LPM was transported to upward layer by resuspension and vertical mixing.