Variability of ozone and oxides of nitrogen in the tropical city, Bengaluru, India.

Bengaluru, also considered India's Silicon Valley, has seen steady growth in population over the years. Bengaluru's rapid development has resulted in dwindling reservoirs, increased traffic congestion, high levels of air pollution, and, to some measure, a rise in summer temperatures. As a result of these changes in urban form over the last decade, anthropogenic heat fluxes for ozone production have increased. However, an observational study on the effects of growing urbanisation on trace gases in Bengaluru for various seasons and periods of the day is missing. Hence, in situ measurements of O3, NO, NO2, and NOX concentrations were carried out at Bengaluru, India, from January 2015 to December 2018. The data were examined for diurnal and interannual variations in trace gas mixing concentrations. The diurnal trend in O3 exhibits unimodal behaviour. Changes in photochemistry, local meteorology, and the planetary boundary layer's distinctive features cause a rise in the value of concentrations and lead to a peak. In contrast, the diurnal trend in NO, NO2, and NOX displayed a bimodal peak due to the combined effect of vehicular emissions and the planetary boundary layer. The link involving the oxidant OX (O3 + NO2) and NOx levels were investigated to determine the NOx-independent regional and NOx-dependent local contributions to OX in the atmosphere. Daytime contributions are higher than night-time contributions, according to the present study. The observed anomalies could be the consequence of photochemical processes that produce OX.

ASSESSMENT OF RADON AND THORON EXHALATION FROM SOILS AND DISSOLVED RADON IN GROUND WATER IN THE VICINITY OF ELEVATED GRANITIC HILL, CHIKKABALLAPUR DISTRICT, KARNATAKA, INDIA.

In this paper, we intend to evaluate the rate of radon and thoron exhalation from soil with reference to the underlying bedrock and gamma dose rate in the environment of elevated granitic hill-Nandi hills of Karnataka. The measurement of exhalation rates for all the soil samples collected from study area was carried out using a continuous radon-thoron monitor (Smart RnDuo monitor). The surface exhalation rate of thoron from soil samples were found to vary from 4160 ± 326 to 21 822 ± 634 mBq m-2 s-1. The mass exhalation rate of radon from soil samples were found to vary from 76 ± 6 to 269 ± 19 mBq kg-1 h-1. Concentrations of radon activity measurements were carried out for all the groundwater samples from study area. A detailed analysis along with physicochemical parameters of water has been made and discussed in this research paper.

A MODEL TO PREDICT 238U IN AQUIFER ROCK BASED ON 222Rn AND 226Ra MEASUREMENT IN GROUNDWATER SAMPLES: A CASE STUDY AT SOUTH BENGALURU CITY, KARNATAKA, INDIA.

Naturally occurring 222Rn and 226Ra concentrations were investigated in groundwater samples collected from different parts of South Bengaluru city using Smart RnDuo monitor developed indigenously by Bhabha Atomic Research Centre (BARC), India. The study area has been divided into two zones on the basis of external gamma radiation dose rates as zone A (100-200 nSv/h) and zone B (above 200 nSv/h). Radon concentration in groundwater for various sites, both supported (contribution from dissolved 226Ra in water) and unsupported (contribution from aquifer rock), was estimated. Assuming that 238U and 226Ra are roughly in secular equilibrium in the aquifer rock, a model has been proposed to predict the uranium (238U) content in the aquifer rocks using onsite measured 222Rn concentration and dissolved 226Ra concentration in the groundwater. Results of a case study carried out at South Bengaluru city, Karnataka, India have been discussed in the paper.