[H-CG26] What scientists should do for reconstruction after Fukushima Daiichi Nuclear Power Plant Accident

[HCG26-P09] Radiocesium transport on the hillslope of a backyard mountain

*Kosuke Noborio¹, Yuki Sunakawa¹, Ryuta Honda¹, Yuki Takagi¹, Masaru Mizoguchi², Taku Nishimura² (1.Meiji University, 2.The University of Tokyo)

Keywords:soil, hydrology, colloid

The radiocesium (Cs) fallout from the Fukushima Dai-ichi Nuclear Power Plant was scraped off from the surface layer on a hillslope of a backyard mountain in Iitate Village, Fukushima Prefecture. Since the fallout radiocesium was removed from the soil surface within a 20 m range from houses, we continued to monitor changes in Cs concentration at the surface layer from the foothill to the Cs-remaining part along the hillslope. Just after the Cs-removing process, Cs concentration on the whole slope was similar from the foothill to the uphill. Radiocesium transport on the hillslope of a backyard mountain seemed to increase during big rainfall events. With time elapsed, Cs concentration seemed to increase in the middle and upper hillslopes. Interestingly, Cs concentration in the Cs-remaining part increased with time, meaning that Cs was transported from the further upper part of the hillslope. Long-term monitoring on the hillslope and vertical transport to the deeper soil layers should be needed.