Effect of Irrigation with Thermal Water on Tomato Uptake of Radium-226, Radium-228 and Potassium-40

The uptake of Radium-226, Radium-228 and potassium-40 by tomato plants as the effect of irrigation with thermal water was studied as pot experiments. Tomato seedlings were grown in 7 L pots filled with four different soil textural classes collected from different locations; silt clay soil (SZ1) and sandy clay loam (SZ2) collected from Zara area at Jordan Valley with 226Ra activity 392 (SZ2) and 5350 (SZ1) Bq∙kg−1. Two control soils also were used; clay loamy soil (SW) and sandy soil (SSa) were collected from Amman with 226Ra activity about 20 Bq∙kg−1 for SW 8.3 Bq∙kg−1. Half of the treatments were irrigated with thermal water while the other half were irrigated with non-thermal water. The average Transfer Factor (TF) for 226Ra values ranged from 0.002 to 0.91 in tomato fruits while in vegetative parts ranging from 0.003 to 2.54 (stems) and from 0.014, to 4.96 (leaves) as a response to irrigation with thermal water. Radium-228 was just detected in tomato leaves that were grown in sandy soil (SSa). High TF was observed for 40K in tomato fruits (8.2 to 133.7) as compared to leaves (1.2 to 16.0) and in stems (1.9 to 11.3). The highest TF values for both 226Ra and 40K were observed in sandy soil. Analysis indicated that source of irrigation water and soil factors affects 226Ra activity in plant tissues while 40K is only affected by its concentration in soil. Although the pot experiment offers controlled conditions for testing, it does not fully replicate field conditions where root depth, soil heterogeneity, and environmental interactions may influence radionuclide uptake. Therefore, the findings should be interpreted with this limitation in mind.