Frequently Asked Questions Joint FAO/IAEA Programme

Publications

Classification of Soil Systems on the Basis of Transfer Factors of Radionuclides from Soil to Reference Plants Classification of Soil Systems on the Basis of Transfer Factors of Radionuclides from Soil to Reference Plants.
IAEA TECDOC Series No. 1497.

Summary

The IAEA, together with the United Nations Food and Agriculture Organization (FAO) and the International Union of Radiologists (IUR), conducted a Coordinated Research Project (CRP) on Transfer of Radionuclides from Air, Soil and Freshwater to the Foodchain of Man in Tropical and Subtropical Environments. This produced a set of values for key transfer parameters of radionuclides between the various components of tropical and sub-tropical ecosystems that can be used in dose assessment models. It concentrated on what are considered as the key parameters in assessment models—radionuclide transfer from soil to plant and from freshwater to fish.

A data bank was developed of transfer factors for radionuclides, principally 137Cs and 90Sr, from soil to cereals, fodder crops including grass, legumes, root crops, green vegetables, and plantation crops. Account was taken of soil properties, nature of the contamination (artificial, weapons testing fallout, Chernobyl fallout and so on) and the type of experiment (field, pot or lysimeter) that generated the values.

For soil-to-plant transfer the following conclusions were drawn:

  1. there are no systematic differences between soil-to-plant transfer factors in temperate, subtropical and tropical environments;
  2. the effect on transfer of a) soil pH, b) nutrient status of the soil and c) time elapsed since the soil was contaminated with radionuclides, is generally independent of the climatic zone;
  3. there exist, however, ecosystems with a relatively high or low uptake (by a factor 10 or even 100 higher or lower than average values);
  4. a higher or lower uptake condition is nuclide specific; an ecosystem may show a relatively high or low uptake for a particular radionuclide and not at all for other radionuclides;
  5. a higher or lower uptake condition is not crop specific. If an ecosystem shows a relatively high or low uptake for one crop, all crops show this behaviour qualitatively.