Assessment of natural radioactivity in drinking water in South Lebanon.

Abstract

Groundwater contains certain levels of radioactivity that arise from the decay of naturally occurring radioactive materials in the adjacent rocks. Radiation is known to have deleterious health effects. As such, assessment of the radioactive concentration levels is essential for determining the suitability of the water for human consumption. The Southern region of Lebanon relies primarily on groundwater sources to fulfill its drinking water requirements. However, information on the radiological properties of the water is lacking. Consequently, this study was initiated to formulate a baseline assessment for natural radioactivity in the area’s water sources. In this context, radioactivity concentrations were determined using liquid scintillation counter for gross alpha, gross beta and radon activity concentrations, and using alpha spectroscopy for those of uranium isotopes. Measurement of gross alpha, gross beta, uranium (238U, 234U) and radon (222Rn) activity concentrations in 42 drinking water supplies (wells, springs, and tap water), sampled over the wet and the dry seasons, showed that all concentrations levels were below the WHO guidance levels. The maximum recorded radioactivity concentrations were 42.9±3.7 BqL-1 for radon, 53.7±2.1 mBqL-1 for 238U, 55.9±2.3 mBqL-1 for 234U, 374.6±11.5 mBqL-1 for gross alpha activities and 418±12 mBqL-1 for gross beta activities; concentrations values, which indicate the suitability of the water for human consumption. Seasonal variations were investigated with only gross alpha activity concentrations showing significant variation between the wet and the dry seasons. Whereas, radon was the only radionuclide to produce significant variation when comparing the radioactivity concentration levels between sources and tap water. On the other hand, no significant variation in radionuclides concentrations was observed between water from springs and that from wells. The calculated effective dose in few locations was relatively high and the radiatio