Transfer factor of Cs and Sr to various crops in semi-arid environment.

This study focuses on evaluating the transfer factor (F) of Cs and Sr from two basic soil types in the country, i.e. Aridisol and Inceptisol, to 18 common crops belong to six groups, i.e. cereals, leafy, non-leafy vegetables, tubers, leguminous fodder and leguminous vegetables. In addition, the variation of Fs of Cs and Sr with crop components, growth stages of plants and the influence of mineral fertilisation were investigated. The experiments were performed in an open field and the results were expressed as geometric means. The data revealed that Fs of both radionuclides were higher in Aridisol than Inceptisol for all crops by about 1.03-4.86 fold. Fs of Sr were more enhanced than those of Cs by one or two orders of magnitude despite plant group and soil type, e.g. Fs ranged 0.12-5.2 for Sr and 0.0035-0.26 for Cs in the vegetative portion of the crops. Among the six crop groups investigated, cereals gave the lowest Fs for both radionuclides, which is compatible with the data reported worldwide. The average Fs observed in cereal grains reached 0.001 for Cs and 0.017 for Sr, in Inceptisol. However, Jew-mallow (one of the major leafy vegetables in the country that is consumed throughout the year) reflected the highest Fs for Cs and Sr, i.e. 0.11 and 2.44 in Inceptisol, respectively. Comparing Fs of the radionuclides through the growing stages of the plants indicated enhanced values at the mid-season than harvest as a consequence of the decrease of the physiological activity of the plants towards maturation and dilution made by the increase of plant biomass; e.g. Fs dropped to about 3.0 fold for Cs and 2.2 for Sr, in Aridisol. Mineral fertilisation of soil (for four crops, i.e. sorghum, barley, spinach and alfalfa) reduced Fs for both radionuclides to an extent of 30% probably because of the competing action of their stable nutrient analogues NH, K or Ca or because of growth dilution. The data presented herein would form a baseline when decision of land-investment or phytoremediation is the preferable countermeasure for the management of Cs and Sr-contaminated soil in semi-arid environment.