Assessment of natural radionuclide transfer factors and partition coefficients in some Syrian soils.

Transfer factors of radium 226(Ra), lead 210(Pb), polonium 210 (Po), uranium 238 (U) and thorium 234(Th) from five different agricultural soils in Syria to coriander, parsley and mint were investigated in a pot culture experiment. Geometric means of transfer factors (TF)wereRa (0.13),Pb(0.03), Po (0.02) and U (1.76) were within worldwide values, while TF values for Th (1.35) were higher than those recorded globally. The available transfer factor (ATF) values ranged between 0.03 and 1.45, 0.33 and 3.2, 0.10 and 3.36, 1.30 and 16.2 and 1.0 and 6.95 forRa,Pb,Po, U and Th, respectively. However, it is worth mentioning that the data from pot experiments may not represent field conditions. Liquid/solid partition coefficients (K)of Ra, U, Pb and Po for55 soils representing the dominant types of soils in Syria were also determined. Geometric means of K values ranged from 280 to1200, 750 to1600, 350to 4800 and 100-120 L kg for Ra, U, Pb and Po, respectively at pH = 4.0, and from 200 to 6700, 670 to 2400, 150 to 2100 and 100 to 160Lkgat pH = 5.5, and from 370 to 790, 130 to 550, 60 to 330 and370 to 920Lkgat pH = 7.0. The effects of soil mineral content, CEC, ECE, pH and soluble ions on the K values were investigated. In general, there were logarithmic relationships between the activity concentrations in soil and the K values (R ranged from 0.59 to 1.00 at pH 4.0). There were no relationships between the K values and soil pH.