Monitoring geothermal springs and groundwater of Pir Panjal, Jammu and Kashmir, for radon contamination

Characterization of thermostable carboxypeptidase from high-altitude hot spring metagenome

This study explored the metagenome of the Pir Panjal Hot Spring (PPHS) to identify thermostable hydrolases. The carboxypeptidase (CarP) gene was successfully amplified and cloned into Escherichia coli DH5-α cells, followed by expression in E. coli BL21-DE3 cells. The CarP enzyme was comprehensively characterized in vitro. Sequencing analysis revealed an open reading frame encoding a functional protein of 504 amino acids, with a molecular weight of 58.65 kDa and an isoelectric point of 4.81. The CarP protein was purified using Ni-His affinity chromatography, and the experimental molecular weight matched in silico predictions. The enzyme exhibited significant thermostability and alkaliphilic properties, with optimal activity at 70 °C and pH 10.0. Additionally, the presence of Zn+2 ions at concentrations of 5 and 10 mmol/L enhanced protease activity by 1.4 and 1.5-fold, respectively. This study reports the discovery of a novel, multifunctional, and thermostable CarP from hot-spring metagenomes. The enzyme's stability against high temperatures, metal ions, surfactants, and inhibitors, along with its specific substrate interactions, highlights its potential for various biotechnological applications.

Radiological assessment of radon in groundwater of the northernmost Kashmir Basin, northwestern Himalaya

This study investigates the radon concentration in groundwater in Kupwara, the northernmost district of the Kashmir valley. It further assesses the annual effective dose experienced by the district's diverse population-infants, children, and adults-attributable to both inhalation of airborne radon released from drinking water and direct ingestion. In addition to this, the calculation of gamma dose rate is also carried out at each of the sampling site of radon. A portable radon-thoron monitor and a portable gamma radiation detector were respectively employed to estimate the activity concentration of radon in water samples and to measure the gamma dose rate. The radon concentration was found to exhibit variability from a minimum of 2.9 BqL-1 to a maximum of 197.2 BqL-1, with a mean of 26.3 BqL-1 and a standard deviation of 23.3 BqL-1. From a total of 85 samples, 10.6% of the samples had radon activity concentrations exceeding the permissible limits of 40 BqL-1 set by the United Nations Scientific Committee on Effects of Atomic Radiations as reported by UNSCEAR (Sources and effects of ionizing radiation, 2008) and only 1.2% of the samples have radon activity concentration exceeding the permissible limits of 100 BqL-1 set by the World Health Organization as reported by WHO (WHO guidelines for drinking-water quality, World Health Organization, Geneva, 2008). The mean of the annual effective dose due to inhalation for all age groups as well as the annual ingestion dose for infants and children, surpasses the World Health Organization's limit of 100 μSv y-1 as reported by WHO (WHO guidelines for drinking-water quality, World Health Organization, Geneva, 2008). The observed gamma radiation dose rate in the vicinity of groundwater radon sites ranged from a minimum of 138 nSv h-1 to a maximum of 250 nSv h-1. The data indicated no significant correlation between the dose rate of gamma radiation and the radon levels in the groundwater. Radon concentration of potable water in the study area presents a non-negligible exposure pathway for residents. Therefore, the judicious application of established radon mitigation techniques is pivotal to minimize public health vulnerabilities.

Radon activity and their radiological doses in drinking water of Chitradurga district, Karnataka, India

In this investigation, radon activity concentration, inhalation and ingestion doses due to intake of radon in drinking water have been estimated in the Chitradurga district drinking water by using radon Emanometry technique. The average radon concentrations vary from 1.81 ± 0.11 to 300.33 ± 4.56 Bql-1 with a mean value of 56.01 ± 2.44 Bql-1. Most of the radon concentration levels are within the World Health Organization (WHO) and European Union (EU) commission recommended level of 100 Bql-1. About 70% of the drinking water had radon concentration level higher than the United States Environmental Protection Agency (USEPA) recommended Maximum Contamination Limit (MCL) of 11.1 Bql-1. The annual ingestion dose varies from 0.38 to 63.03 μSvy-1 with an average value of 11.75 μSvy-1. The estimated annual ingestion dose is well within the WHO recommended reference level of 100 μSvy-1.

A study on measuring the 222Rn in the Buriganga River and tap water of the megacity Dhaka

Radon (222Rn), an inert gas, is considered a silent killer due to its carcinogenic characteristics. Dhaka city is situated on the banks of the Buriganga River, which is regarded as the lifeline of Dhaka city because it serves as a significant source of the city's water supply for domestic and industrial purposes. Thirty water samples (10 tap water from Dhaka city and 20 surface samples from the Buriganga River) were collected and analyzed using a RAD H2O accessory for 222Rn concentration. The average 222Rn concentration in tap and river water was 1.54 ± 0.38 Bq/L and 0.68 ± 0.29 Bq/L, respectively. All the values were found below the maximum contamination limit (MCL) of 11.1 Bq/L set by the USEPA, the WHO-recommended safe limit of 100 Bq/L, and the UNSCEAR suggested range of 4-40 Bq/L. The mean values of the total annual effective doses due to inhalation and ingestion were calculated to be 9.77 μSv/y and 4.29 μSv/y for tap water and river water, respectively. Although all these values were well below the permissible limit of 100 μSv/y proposed by WHO, they cannot be neglected because of the hazardous nature of 222Rn, especially considering their entry to the human body via inhalation and ingestion pathways. The obtained data may serve as a reference for future 222Rn-related works.

Radiological risk assessment to the public due to the presence of radon in water of Barnala district, Punjab, India

Various research studies have shown that exposure to radon gas is a cause of concern for health effects to the public. The present work has been carried out for the radiological risk assessment to the public due to the presence of radon isotopes in drinking water of Barnala district of Punjab, India, for the first time using scintillation-based radiation detector. A total of 100 samples were collected from different sources of water (canal and underground water) from 25 villages on grid pattern of 6 × 6 km² in the study area for uniform mapping. In situ measurements were carried out to find out Rn-222 concentration in water samples. The measured values have been found to vary from 0.17 ± 0.01 to 9.84 ± 0.59 BqL^-1 with an average value of 3.37 ± 0.29 BqL^-1, which is well below the recommended limit of 100 BqL^-1(WHO 2004). The annual effective dose due to ingestion and inhalation of radon has also been calculated for various age groups like infants, children and adults to understand the age-wise dose distribution. The calculated values suggest that there is no significant health risk to the general public from radon in water.

Effect of heat treatment on the emission rate of radon from red sandstone

High temperature and pore structure are important factors affecting the emission rate of radon in rocks. This study mainly focused on the correlation between radon emission rate and temperature in red sandstone. The results showed that in the temperature range of 25-400 °C, as the temperature increased, the connectivity of the internal pores of the sample became better, resulting in a significantly increased radon emission rate. The radon emission rate at 400 °C was 2.86 times the original. To explain the changes that occurred in the internal structure of the samples, the porosity characteristics of the samples after heat treatment were studied by nuclear magnetic resonance (NMR). It was found that the pore structure was also an important factor affecting the rate of radon emission. The smaller pore size of the micropores (r < 0.1 μm) inhibited the emission of radon in the sandstone. These results helped in understanding the mechanism of radon emission rate and provide an important basis for predicting rock fragmentation and coal fire.