Radon levels in groundwater in the Tuticorin district of Tamil Nadu, South 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.

Measurement of submarine groundwater discharge (SGD) into Tiruchendur coast at southeast India using 222Rn as a naturally occurring tracer

Application of natural tracers such as radon isotope mass balance has been useful in estimating the submarine groundwater discharge (SGD). This study used ²²²Rn and evaluated the magnitude of SGD at Tiruchendur coast of southeast India in the Gulf of Mannar (Indian Ocean). Higher magnitudes of ²²²Rn in the porewater and seawater in comparison with the groundwater suggest simultaneous SGD with fluxes of 0.1-0.25 m³ m^-2 d^-1 at offshore and 0.4-0.20 m³ m^-2 d^-1 at the near shore. These baseline data would contribute to the management and protection of the Gulf of Mannar region in near future.

Role of lithology in the presence of natural radioactivity in drinking water samples from Tarragona province

One hundred and ninety-six drinking water samples from the different regions of Tarragona province (Catalonia, Spain) were analysed to determine the gross alpha and beta activity. Individual alpha emitting isotope activities were also determined to evaluate a possible relationship between their radiological content and the lithological and hydrogeological formations present in the studied area. The results obtained showed that approximately 23% of the analysed samples, mainly from five of the evaluated regions, had a gross alpha index exceeding the parametric value of 0.1 Bq/L for waters intended for human consumption according to the current legislation. This could be related to the presence of natural radionuclides in these water samples. The differences between the radiological content in these samples could be related to the different lithological conditions of the areas included in this study. High activity levels of ²³⁴U, ²³⁸U, ²²⁴Ra, ²²⁶Ra and ²²⁸Ra were detected in specific samples, mainly from granitic and carbonate areas. This research also focuses on evaluating the radiological risk associated with water ingestion. In this regard, consuming 95.5% of the drinking water samples analysed would not imply a health risk to the population as the annual effective doses calculated were below 0.1 mSv/year. There was only one sample that exceeded this level with a value of 0.33 mSv/year. ²²⁶Ra activity concentration was the radionuclide that mainly contributed to this dose.

A STUDY ON THE RADIATION DOSE DUE TO DISSOLVED 222RN IN WATER SAMPLES OF MANDYA CITY, KARNATAKA, INDIA

Measurement of dissolved radon concentrations in the water samples collected from selected borewells (depth ~300 ft), wells (depth ~25 ft) and overhead tanks (height ~30 ft) of Mandya city, Karnataka, India, has been carried out by using Emanometry method. The radon concentrations in the waters of borewell, well and overhead tank ranges from 1.5 ± 0.1 to 102.8 ± 5.1, 1.3 ± 0.1 to 3.8 ± 0.4 and 2.5 ± 0.2 to 9.7 ± 1.1 Bq l-1 with the mean values of 16.8, 2.5 and 6.2 Bq l-1, respectively. Majority of borewell water samples showed higher concentrations of dissolved 222Rn compared to waters of well and overhead tank. The overall mean value of dissolved radon concentration of 12.2 Bq l-1 is found to be close to the maximum contaminant level of 11 Bq l-1 suggested by US Environment Protection Agency. The physicochemical parameters like pH, TDS and conductivity were also measured, and dependence of dissolved 222Rn on these parameters has been studied. Using the mean value of dissolved radon concentration, a new attempt has been made to compute the doses imparted to different organs and tissues of the human body. Dosimetric calculations showed that stomach and small intestine receive greater doses due to dissolved radon compared to other organs.

Evaluation of radiation dose from radon ingestion and inhalation in groundwater of a small tropical river basin, Kerala, India

A comprehensive study was conducted to understand the radon (²²²Rn) distribution and associated radiation doses to the public in a small tropical river basin partly set in the western slope of the Southern Western Ghats of Kerala, India. Radon, though detected in all the 71 monitored wells (0.17-68.3 Bq L^-1), exceeded the maximum contamination level (MCL) of 11.1 Bq L^-1 for drinking water recommended by United States Environmental Protection Agency (USEPA) in eight samples from isolated pockets of highland, midland and lowland of the Karamana River Basin (KRB) and found to be well within 100 Bq L^-1, the parametric value suggested by the World Health Organization (WHO) and the European Union (EU). The age-wise total annual effective doses (AEDs) of groundwater radon activity ranged from 0.5-208.4 μSv a^-1 for infants, 0.4-172.2 for children and 0.5-189.7 μSv a^-1 for adults. The results reveal that effective doses due to groundwater radon pose no potential public health risk in the study region. Since there is no previous background information on radon-induced radiation dose in the KRB, this work is a newfangled attempt from a public health point of view.

Factors controlling the distribution of radon (222Rn) in groundwater of a tropical mountainous river basin in southwest India

Studies on occurrence of radon in the environment are receiving growing attention worldwide due to its adverse impact on human health. Despite that, the dissolved radon in water is found to be a useful tracer in many hydrogeological studies. Although, several studies focused on the occurrence of high ²²²Rn in groundwater, the processes responsible for its variation is still not well understood. Hence, an attempt has been made in the present study to elucidate the underlying factors influencing the abundance ²²²Rn in hard rock (gneissic) aquifers of Karamana River Basin, southwest India. ²²²Rn in groundwater was analyzed in 71 dug wells during the pre-monsoon period of 2017. A large variability in ²²²Rn activities (170-68,350 Bq/m³) was noticed in groundwater and high activities were mainly seen in the khondalite formation. No significant dependencies between ²²²Rn activity and depth to water table, groundwater temperature and electrical conductivity were observed. However, majority of the presence of high ²²²Rn activity in groundwater matches with the location of lineaments. Furthermore, radium content in the host rock, degree of weathering and fracturing and the emanation coefficient of the rock were found to have an important bearing on the occurrence of radon in groundwater. The underlying factors influencing the abundance of radon in hard rock aquifers were also conceptualized. Thus, the study highlights the usefulness of ²²²Rn as a potential tool in delineating the macro-structural features like fractures/lineaments that are significant repositories of groundwater, which could be explored for groundwater development in hard rock terrains.

RADON IN GROUNDWATER OF MAGADI TALUK, RAMANAGARA DISTRICT IN KARNATAKA

Radon is a water-soluble radioactive noble gas produced from the alpha decay of 226Ra in uranium series. Its presence in drinking water and open air increases the risk of lung and intestinal cancers in human beings. In view of this, radon concentration in groundwater and its dose due to inhalation and ingestion to the population of Magadi taluk of Ramanagara district in Karnataka state, India was studied. The groundwater samples were analyzed for radon concentration using emanometry technique. The study showed that the radon concentration in this area varied from 27.4 ± 1.0 to 167.5 ± 3.9 Bq/L and the effective dose ranged from 104.2 ± 2.7 to 636.2 ± 11.0 μSv/a. The study also revealed that 95% of the 37 samples studied showed higher radon concentration compared to the UNSCEAR recommendation (40 Bq/L) and all the samples showed higher than the USEPA recommendation (11.1 Bq/L). Ten samples have concentration above the maximum permissible level prescribed by WHO (100 Bq/L). The groundwater samples are found to be slightly alkaline within the permissible limit of Indian Standards.