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

Abstract

Transfer factors of radium 226(226Ra), lead 210(210Pb), polonium 210 (210Po), uranium 238 (238U) and thorium 234(234Th) 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)were226Ra (0.13),210Pb(0.03), 210Po (0.02) and 238U (1.76) were within worldwide values, while TF values for 234Th (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 for226Ra,210Pb,210Po, 238U and 234Th, respectively. However, it is worth mentioning that the data from pot experiments may not represent field conditions. Liquid/solid partition coefficients (Kd)of 226Ra, U, 210Pb and 210Po for55 soils representing the dominant types of soils in Syria were also determined. Geometric means of Kd values ranged from 280 to1200, 750 to1600, 350to 4800 and 100-120\xa0L kg-1 for 226Ra, 238U, 210Pb and 210Po, respectively at pH\xa0=\xa04.0, and from 200 to 6700, 670 to 2400, 150 to 2100 and 100 to 160Lkg-1at pH\xa0=\xa05.5, and from 370 to 790, 130 to 550, 60 to 330 and370 to 920Lkg-1at pH\xa0=\xa07.0. The effects of soil mineral content, CEC, ECE, pH and soluble ions on the Kd values were investigated. In general, there were logarithmic relationships between the activity concentrations in soil and the Kd values (R2 ranged from 0.59 to 1.00\xa0at pH 4.0). There were no relationships between the Kd values and soil pH.