UPTAKE OF 226Ra FROM IRRIGATION WATER BY BASIL CROPS

The transfer of Ra-226 from irrigation water to basil crops was studied in field conditions. A dedicated basil plot was established and divided into test and control subplots irrigated with water having high (2.1 Bq L-1) and low (0.05 Bq L-1) activity concentrations of Ra-226, respectively. The experiment was performed over a period of 18 months during the autumn, winter and spring seasons, altogether eight cycles of growth and harvest. The activity concentration of Ra-226 in basil grown in the test subplots was found to increase from a value of 0.6 Bq kg(-1) up to 5.1 Bq kg(-1) with successive cycles, compared to a mean value of 0.2 Bq kg(-1) for basil grown in the control subplots. The increase in activity concentration of Ra-226 in basil grown in the test subplots is mainly attributed to its build-up in the soil in which the level of Ra-226 was found to increase by similar to 40%. The effective uptake of Ra-226 from the irrigation water (via soil) by the basil plants was found to be approximately 0.4%. The maximal radiation dose following consumption of basil crops grown in the test subplots is negligible (similar to 3 mu Sv/y).