Sustainable agricultural use of natural water sources containing elevated radium activity

• The environmental implications of using water containing Ra for irrigation were investigated.
• Radium was found to accumulate in crops leaves following the evapotranspiration current.
• Sorption of 226Ra to soil particles hinders its matrix mobility.
• Crops can be irrigated with the activity of 226Ra of 0.6–1.6 Bq L−1.

Relatively elevated concentrations of naturally occurring radium isotopes (226Ra, 228Ra and 224Ra) are found in two main aquifers in the arid southern part of Israel, in activity concentrations frequently exceeding the limits set in the drinking water quality regulations.We aimed to explore the environmental implications of using water containing Ra for irrigation. Several crops (cucumbers, melons, radish, lettuce, alfalfa and wheat), grown in weighing lysimeters were irrigated at 3 levels of 226Ra activity concentration: Low Radium Water (LRW) < 0.04 Bq L−1; High Radium Water (HRW) at 1.8 Bq L−1 and (3) Radium Enriched Water (REW) at 50 times the concentration in HRW. The HYDRUS 1-D software package was used to simulate the long-term 226Ra distribution in a soil irrigated with HRW for 15 years. Radium uptake by plants was found to be controlled by its activity in the irrigation water and in the soil solution, the physical properties of the soil and the potential evapotranspiration. The 226Ra apeared to accumulate mainly in the leaves of crops following the evapotranspiration current, while its accumulation in the edible parts (fruits and roots) was minimal. The simulation of 15 years of crop irrigation by HYDERUS 1-D, showed a low Ra activity concentration in the soil solution of the root zone and a limited downward mobility. It was therefore concluded that the crops investigated in this study can be irrigated with the natural occurring activity concentration of 226Ra of 0.6–1.6 Bq L−1. This should be accompanied by a continuous monitoring of radium in the edible parts of the crops.