Radiological characterization of drinking water sources in copper belt, Aravalli hill and mining-affected regions of Northern Rajasthan.

This paper gives an evaluation of the concentration of dissolved 222Rn in groundwater samples of Copper belt and Aravalli hill regions of Jhunjhunu district and red granite mining areas of Bikaner district of Northern Rajasthan in India and provides an assessment of the radiological health risks. Total 200 water samples were collected from various depths, 10 locations from mining sites belonging to Bikaner district and 10 from copper belt and Aravalli hills belonging to Jhunjhunu district (5 deep borewells and 5 tap water systems/storage water from each location) were analyzed using a RAD7 detector with a smartly attached degassing unit. The measured 222Rn activity less than 2.1 Bq L-1 in tap/storage water and as high as 586 ± 105 Bq L-1 in a deep borehole tapping uranium-enriched fractured aquifers. Deep groundwater had the highest concentrations, while open wells and tap water usually having low radon because of the degrees of radon storage/transport. Annual doses due to ingestion and inhalation were calculated using standard dose conversion factors for different age groups like infants, children, and adults. For all type of ages, annual effective doses from all the deep groundwater samples due to ingestion and inhalation exceed the guideline limits of World Health Organization limit (0.1 mSv y-1) for drinking water. These findings further bring to the fore possible lung-cancer hazard and emphasize mitigation strategies.