Research Activities

After radioactive substances discharged from the Fukushima Daiichi Nuclear Power Plant accident and deposited on the land, they entered into dynamic processes that continually move the radionuclides by physical (e.g., wind, rain) and biological methods (e.g., uptake by plants). To reduce the risk of radiation, it is necessary to understand the movement processes and be able to predict where the radiation will be in the future.

For example, cesium-137 attaches to soil particles and is transported with the soil by erosion when it rains, flowing into the sea through rivers. In addition, the soil-bound cesium accumulates as sediments in closed water basins like lakes and marshes. The detachment of cesium away from soils is a slow process that is governed by chemical changes. This knowledge was formed from research on radioactive substances in the past.

However, because Fukushima has more rainfall and its geographical features are much steeper, the conditions that govern the movement of radioactive substances are different from those that have been previously studied. On the basis of these differences, and making good use of past knowledge, our research seeks to clarify the original condition of radioactive substances on the land in Fukushima Prefecture so that we can predict where it will reside in the future.

IER’s ecosystem group focuses on radioecological field studies within the human exclusion zones of Fukushima and Chernobyl.

“Radioecology” is a scientific discipline that studies the movement of radionuclides in the environment, and the effects of the environmental radiation on plants, animals and humans.

We are taking a systems approach to our research by linking molecular, individual, population and community level impacts from radiation exposures. We recognize that many confounding variables in field research can cause bias when interpreting research data. For example, the evacuation and resettlement of humans is likely having a profound effect on populations of wildlife. Thus, the dynamics of human residency in the contaminated zones will need to be a co-factor to consider when determining the effects of radiation on populations of wildlife, such as wild boar.

Our group is also specializing in methods to measure radiation dose to free-ranging wildlife. Improved dosimetry is not only important for critical evaluation of long term radiological effects on wildlife populations, but also for assessing potential health effects to humans as they repopulate evacuation zones.

It is very important to accurately measure radionuclides in the environment so that we can better predict their behavior. Knowing their behavior helps predict their potential effects to humans and the environment. However, most radionuclides can occur in several different forms within the environment, and these forms can have widely different behaviors, even if the different forms occur for the same radionuclide.

At the IER, we are taking “existing form” in a broad sense. We study radionuclides based on their bonding states and the environmental substances in which they are associated. Often we use advanced methods to separate the various forms in which a radionuclide resides. Once the various chemical forms of radionuclides are identified and quantified, we can make a better estimate of their environmental transport and fate. This knowledge is critical to improved human and environmental risk analyses.