Comparison of the vertical distributions of Fukushima nuclear accident radiocesium in soil before and after the first rainy season, with physicochemical and mineralogical interpretations

► The first rainy season effect on Fukushima accident 137Cs in soil was found limited. ► The 137Cs relaxation lengths were almost unchanged before and after the rainy season. ► The sum of water soluble and exchangeable 137Cs in soil was limited to about 10%. ► Mineralogical effects may be masked by the soil physicochemical properties.