Radiological and hydrological implications of dissolved radon in alluvial aquifers of western India

Radon concentration measurement and effective dose assessment in drinking groundwater for the adult population in the surrounding area of a thermal power plant

Radon in the household water collected from hand pumps is measured using a continuous radon monitor. Water samples are collected from 25 villages from the surrounding regions of the National Capital Power Cooperation (NTPC), Dadri. The radon concentration ranges from 17±1 to 68±3 Bql^-1 with a mean value of 33±13 Bql^-1. The measured radon concentration in all collected samples lies well within the limit of 100 Bql^-1as set by the World Health Organization (WHO). The mean values of the annual effective dose due to ingestion of radon and due to the inhalation of radon released from water are 84±33 and 167±65 μSvy^-1, respectively. In addition, the mean values of estimated total annual effective doses are found to be 167±65 μSvy^-1. The mean value of total annual effective doses is found to be higher than the reference dose level of 100 μSvy^-1 recommended by the WHO and the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR). The mean values of effective doses per annum to the lungs and stomach are 9.9±3.9 and 10.1±3.9 μSv, respectively.

Distribution and correlation of radon and uranium and associated hydrogeochemical processes in alluvial aquifers of northwest India

The spatial and vertical distributions of radon and uranium are evaluated in relation to the hydrogeology, geomorphology, and hydrochemistry of southwest Punjab. Radon activity of the groundwater ranges from 580 to 3633 Bq/m³ (shallow groundwater 580 to 2438 Bq/m³ and deep groundwater 964 to 3633 Bq/m³), and uranium concentration varies from 24.4 to 253 μg/L (shallow groundwater 24.4 to 253 μg/L and deep groundwater 27.6 to 76.3 μg/L). Shallow groundwater shows higher U concentration compared with deeper ones, which can be attributed to the presence of dissolved oxygen (DO) and NO₃^- as oxidants and HCO₃^- as stabilizing agent in shallow zone. Unlike uranium, the radon activities were found to be similar in both shallow and deep groundwater. Rn_excess over secular equilibrium was used to confirm the possibility of additional sources of radon, such as secondary minerals present in the subsurface. Surface manifestations show significant influence on radon and uranium distributions in the shallow zone but not in deep zone due to limited hydraulic connectivity. Depth profiles and correlations of radon and uranium with trace elements and hydrochemical parameters indicate that groundwater exhibits different redox characteristics in shallow (younger and oxidizing) and deep zones (older and reducing). The present study provides critical information that can be helpful for planning sustainable groundwater development in this region and other similar regions without contaminating the relatively safer deep aquifers.