Currently, decisions concerning agricultural countermeasures are mostly based on empirical and semi-mechanistic models of soil-to-plant transfer that were developed for European soils under temperate conditions in the aftermath of the Chernobyl accident. But these models do not predict radiocaesium transfer from Japanese soils realistically as post Fukushima experience has shown, indicating influence of regional characteristics (e.g. climate conditions, soil properties, crop type, land management practices) on Cs bioavailability.
As new countries in Asia, Africa and South America are adopting nuclear energy, radiocaesium soil-plant transfer models will be required to make predictions under diverse environmental conditions (e.g. tropical, arid). Recently, the International Atomic Energy Agency (IAEA) has initiated the Coordinated Research Project (CRP) “Monitoring and predicting radionuclide uptake and dynamics for optimizing of radioactive contamination in agriculture” to improve the robustness of these soil-plant transfer models for the underexplored areas, crops and climates.
This PhD proposal is in line with the IAEA CRP. It aims to better understand radiocesium mobility and availability to plants in a wide range of soil and plant types, especially for non-temperate environments, and to use this understanding to improve or develop soil-plant transfer models that can predict radiocesium transfer across environments with minimum adjustment. We hypothesize that radiocesium mobility and availability to plants are controlled by a unique set of soil parameters that can be measured with simple soil tests. Models using these parameters will be able to predict radiocesium transfer across different environments with few inputs.
To test this hypothesis, the candidate will:
- Re-analyze soil and soil-plant transfer data from Chernobyl, Japan and other past experimental studies and measuring missing important soil parameters (e.g. clay mineralogy, RIP/unit clay, ageing effect) on the soils that are still available from these studies. The aim is to get better quantitative insights in the radiocesium behavior in soils and its uptake by plants. These data will be used to make an updated soil-plant transfer model that is valid for both the European (Chernobyl) and Japanese data.
- Develop a more robust soil-plant transfer model by
- Exploring georeferenced samples of soils worldwide with properties not covered by the existing model. Our focus will be on underexplored environments on other continents (e.g. tropical, monsoon, arid).
- Understanding the radiocaesium sorption and ageing properties on these soils and relate these to soil mineralogy, soil classification (soil map data) and traditional physico-chemical properties
- Translating the better understanding of the radiocesium behavior in soils and its uptake by plants into a new, more robust, version of the soil-plant model
- Refining and testing the overall validity of the new soil-plant model by setting up soil-plant experiments with a selective subset of soils with distinct soil parameters and representative for the soil types present around nuclear power plants (NPPs) world-wide for different plant categories (grass, cereals, leafy vegetables, root vegetables) to include plant properties.