Challenges in radioecology.

Today, radioecology covers a broad scientific field; from the source to long term environmental impact from ionizing radiation. To summarize key challenges within radioecology, the present paper focuses upon knowledge gaps related to processes, mechanisms and variables contributing most to the overall uncertainties in environmental impact assessments. A series of sources related to the nuclear weapon cycle and the civil nuclear cycle has contributed, is still contributing or can potentially contribute to release of radionuclides to the environment in the future. The speciation of most radionuclides depends on the source and release conditions, and will influence ecosystem transport, biological uptake, doses and effects in flora and fauna. Radionuclides may also co-occur in contaminant mixtures (e.g., metals, organics), which potentially could lead to synergisms or antagonisms. Thus, challenges associated with the links between the source or release term - radionuclide speciation - ecosystem transfer - exposure - response relationships are highlighted.