Transfer factors of 137Cs and 90Sr from soil to trees in arid regions

Transfer factors of 137Cs and 90Sr from contaminated soil (Aridisol) to olive, apricot trees and grape vines were determined under irrigated field conditions for four successive years. The transfer factors (calculated as Bq kg−1 dry plant material per Bq kg−1 dry soil) of both radionuclides varied among tree parts and were highest in olive and apricot fruits. However, the values for 90Sr were much higher than those for 137Cs in all plant parts. The geometric mean of the transfer factors in olives, apricots and grapes were 0.007, 0.095 and 0.0023 for 137Cs and 0.093, 0.13 and 0.08 for 90Sr, respectively, and were negligible in olive oil for both radionuclides. The transfer factors of both radionuclides were similar to, or in the lower limits of, those obtained in other areas of the world. This could be attributed to differences in soil characteristics: higher pH, lower organic matter, high clay content, and higher exchangeable potassium and calcium.