Radioactivity Dynamics in River System
ＱWhat kinds of places have high concentrations of cesium dissolved in river water?
ＡWe analyzed cesium concentrations in river water sampled at 66 locations in eastern Japan, mainly Fukushima Prefecture, over a period from August to September 2017. The results show that the concentration of cesium dissolved in river water is correlated with the average cesium deposition amount in the river basin.
We have also found that the smaller the ratio of the land area with buildings is in the basin, the lower the cesium concentration is.
The concentration of cesium dissolved in river water (dissolved cesium) is far below the limits for drinking water (1 Bq/L).
However, with shipping restrictions still imposed on some freshwater fish species and freshwater fish caught in some areas, studies are ongoing to investigate the situation of river water in detail.
Fig.2 Concentration of Cs-137 dissolved in river water in relation to average Cs-137 deposition amount in the river basin
The larger the cesium deposition amount in the river basin is, the higher the concentration of cesium dissolved in river water is.
Fig.3 Concentration of Cs-137 dissolved in river water in relation to the ratio of the land area with buildings
The higher the ratio of the land area with buildings is (i.e., more flatlands), the higher the concentration of cesium dissolved in river water is.
(Research results from the National Institute for Environmental Studies and others)
- Do radioactive cesium concentrations in trees increase over time? If so, can such trees be used as timber?
- In future, what will be radiation exposures to forest workers? Are there any methods to reduce it?
- How much amount of radiocesium discharges into the ocean?
- Dose the radiocesium discharge ratio from rivers depend on the local environment?
- Any method to evaluate damaged location by the forest fire?