Spatial modelling of transfer of long-lived radionuclides from soil to agricultural products in the Chernigov region, Ukraine

Within the RESTORE project ('restoration strategies for radioactive contaminated ecosystems') funded by the European Commission Nuclear Fission Safety Programme, environmental models are being developed to identify regions that are vulnerable to increased radionuclide transfer as a consequence of the Chernobyl nuclear power plant accident and nuclear weapons testing at the Semipalatinsk test site in Kazakhstan. Since radionuclide transfer varies in space and time depending on deposition processes, soil type, land use, and resulting contamination in food products, the radionuclide transfer through food chains derived from a variety of ecosystems is analysed by the use of models embedded in a Geographical Information System. The Chernigov region in northern Ukraine was affected by the Chernobyl fallout resulting in deposition levels ranging from 15 to 300 kBq m-2. GIS-based steady state and dynamic transfer models within an environmental decision support system (EDSS) were run for this region to model radiocaesium transfer from soil to various agricultural products on a collective farm level and on a district level within this region using spatial data sets of soil attributes, soil contamination and land use. Observed agricultural product contamination was available for comparison with model predictions. This paper presents examples of radiocaesium transfer from soil to fodder grass and potatoes to make an initial assessment of the radioecological situation in the Chernigov region to identify critical gaps in the model structure and data required for model input and validation. It highlights the feasibility of applying spatial and temporal data sets to make predictions of the present radioecological situation, as an alternative to approaches commonly used which categorise such data sets, thereby losing valuable information.