137Cs concentration where sediment continuously deposit】｜Base Info Q&A｜JAEA

Base Information Q&A SiteJAEA

Japanese

Radioactivity Dynamics in River System

（2016）

ＱDo high concentrations of radioactive cesium continue to be deposited on riverbeds? 【137Cs concentration where sediment continuously deposit】

ＡDeposition will continue at high water channel where plants grow thickly and tend to deposit soil containing 137Cs. However, the concentration of 137Cs in newly deposited soil tend to decrease.

Time change of depth distribution of concentration of 137Cs in high water channel in Ukedo river and Kuma river

Fig.1　Time change of depth distribution of concentration of 137Cs in high water channel in Ukedo river (upper) and Kuma river (lower)
■: Primary deposition
■: Deposition until Oct 2013
■: Deposition until Dec 2014

※ Order in the figure means amount of 137Cs deposition per unit area (1m2) per thickness of the deposit (1cm).


● Tendency described below can be seen by investigation case in Ukedo river and Kuma river in Fukushima pref.

  1. A river which upstream area is relatively high 137Cs deposition (Ukedo river) ：
    The concentration of 137Cs in the river bed increased by soil containing 137Cs, which inflow from upstream area and deposit immediately after accident, but thereafter, it tend to decrease.
  2. A river which upstream area is relatively low 137Cs deposition (Kuma river) ：
    The concentration of 137Cs in the surface soil of riverbed tend to decrease by deposition of soil.

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