A comparative study of riverine Cs dynamics during high-flow events at three contaminated river catchments in Fukushima.

This study presents the temporal variations in riverine Cs concentrations and fluxes to the ocean during high-flow events in three coastal river catchments contaminated by the Fukushima Daiichi Nuclear Power Plant accident. River water samples were collected at points downstream in the Niida, Ukedo, and Takase Rivers during three high-flow events that occurred in 2019-2020. Variations in both the dissolved and particulate Cs concentrations appeared to reflect the spatial pattern of the Cs inventory in the catchments, rather than variations in physico-chemical properties of water and suspended solid.

Importance of desorption process from Abukuma River's suspended particles in increasing dissolved Cs in coastal water during river-flood caused by typhoons.

Desorption of radiocesium (Cs) from riverine particles into seawater strongly influences Cs concentrations in coastal seawater. This process is important for quantifying the input of radionuclides to marine environments. Here we quantify the particulate Cs flux from the Abukuma River, Japan, during typhoon Hagibis and following typhoons in 2019 and estimate the resulting increased dissolved Cs levels in coastal seawater.