• Investigation at Ogaki dam in Fukushima pref. revealed that the concentration of ¹³⁷Cs in bottom sediment and precipitation particle was high just after accident and tend to gradually decreasing with time.
• This finding is in good agreement with the tendency for cesium flowing from forests into mountain rivers to be gradually decreasing with time (see Q Is there a continuous input of cesium contamination to rivers from forests?).

Fig.1　Map of Ogaki dam and sampling position of bottom sediment and precipitation particle
Map is cited from Map data by Geographical Survey Institute

Fig.2　Time change of radioactive cesium concentration of these sediment and sedimented particles

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