Soil to plant transfer of 239 + 240Pu, 238Pu, 241Am, 137Cs and 90Sr from global fallout in flour and bran from wheat, rye, barley and oats, as obtained by field measurements.

Crops of wheat, rye, barley and oats were grown on fields where the contamination of the soil with radionuclides resulted exclusively from global fallout debris. After machine harvesting and milling, the concentrations of 239 + 240Pu, 241Am, 137Cs and 90Sr were determined separately in bran and flour, as well as in the soils. The concentrations of 239 + 240Pu in wheat, rye and barley flour were between 59 and 180 microBq kg-1, and in oat flour 1100 microBq kg-1. The range of concentrations of the other radionuclides for the four flours were: 241Am, 5-70 microBq kg-1, 137Cs, 260-380 mBq kg-1; 90Sr, 310-1300 mBq kg-1. The corresponding concentrations of the radionuclides were always considerably higher in the bran than in the flour, with the exception of oats. The range of this factor depends on the cereal: for 239 + 240Pu, 19-25; 241Am, 10-38; 137Cs, 4-6; and for 90Sr, 4-7. Similar differences between flour and bran were observed for stable elements, for example K, Ca and Fe. The soil-to-plant transfer factors of 239 + 240Pu for wheat, rye and barley flour were between 0.00026 and 0.00078 (oats 0.017) and for bran between 0.0048 and 0.02 (oats 0.014). For 241Am the corresponding values were somewhat lower. For the wheat, rye and barley flour the transfer factors of 137Cs were between 0.013 and 0.018 (oats 0.069) and, for the bran, between 0.08 and 0.10 (oats 0.16). The corresponding values for 90Sr were significantly higher: for flour between 0.08 and 0.14 (oats 1.2) and for bran between 0.62 and 0.93 (oats 1.5).