Aparna Satsangi

Comparison of BTX Profiles and Their Mutagenicity Assessment at Two Sites of Agra, India

In the present study, the concentrations of three volatile organic compounds (VOCs), namely, acronym for benzene, toluene, and xylenes (BTX) were assessed because of their role in the tropospheric chemistry. Two representative sites, a roadside and a petrol pump, were chosen for sample collection. VOCs were collected using SKC-activated charcoal tubes and SKC personal sampler and characterized by gas chromatograph using flame ionization detector. Among BTX, benzene had the highest concentration. At the roadside, mean concentration of benzene, toluene, o-,m-xylene, and p-xylene were 14.7 ± 2.4 μgm−3, 8.1 ± 1.2 μgm−3, 2.1 ± 0.8 μgm−3, and 5.1 ± 1.2 μgm−3, respectively. At the petrol pump, the mean concentrations of benzene, toluene, o-,m-xylene and p-xylene were 19.5 ± 3.7 μgm−3, 12.9 ± 1.1 μgm−3, 3.6 ± 0.5 μgm−3 and 11.1 ± 1.5 μgm−3, respectively, and were numerically higher by a fraction of 2. Monthly variation of BTX showed maximum concentration in winter. Inter-species ratios and inter-species correlation indicated traffic as the major source of BTX. Extracts of samples were positive in both Salmonella typhimurium tester strains TA98 and TA100 without metabolic activation suggesting the presence of direct mutagens in ambient air that can cause both frame-shift and base-pair mutation. The mutagenic response was greater for TA100 than TA98 suggesting greater activity for base-pair mutagenicity than frame-shift mutagenicity and was found to be statistically significant.

Characterization and Mutagenicity Assessment of PM2.5 and PM10 PAH at Agra, India

Fine airborne particulate matter and bound chemical compounds are potential mediators of adverse health effects. In this study, PM2.5 and PM10 were characterized for bound polycyclic aromatic hydrocarbons (PAHs) and the mutagenic potential of extracts was assessed. PM2.5 and PM10 samples were collected on glass fiber filters at Agra from July to December 2010 using a fine particulate sampler (Envirotech, APM 550). The content of PAH was analyzed by gas chromatography and the extract were tested for mutagenicity by the Ames test without using S9. Individual PAH concentration varied from 13–172 ng m−3 with concentration for Chrysene and a dominance of low molecular weight compounds. Both PM and PAH concentrations were higher in the winter and were negatively correlated with temperature and wind speed. Diagnostic ratio analysis indicated contributions from vehicular exhaust and emissions from combustion of domestic fuel like coal and wood. Mutagenicity assays indicated the presence of mutagens capable of causing base pair and frame shift mutagenicity; however, within the range of tested concentrations no significant toxic effects were detected.

Surface ozone concentrations in Agra: links with the prevailing meteorological parameters

Measurements of surface ozone (O3), nitric oxide (NO), nitrogen dioxide (NO2), oxides of nitrogen (NOx=NO+NO2) and meteorological parameters have been made at Agra (North Central India, 27°10’N, 78°05’E) in post monsoon and winter season. The diurnal variation in O3 concentration shows daytime in situ photochemical production with diurnal maximum in noon hours ranging from 51 to 54 ppb in post monsoon and from 76 to 82 ppb in winter, while minimum (16–24 ppb) during nighttime and early morning hours. Average 8-h O3 concentration varied from 12.4 to 83.9 ppb. The relationship between meteorological parameters (solar radiation intensity, temperature, relative humidity, wind speed and wind direction) and surface O3 variability was studied using principal component analysis (PCA), multiple linear regression (MLR) and correlation analysis (CA). PCA and MLR of daily mean O3 concentrations on meteorological parameters explain up to 80 % of day to day ozone variability. Correlation with meteorology is strongly emphasized on days having strong solar radiation intensity and longer sunshine time.

Polycyclic Aromatic Hydrocarbon Emissions and Mutagenicity Assessment of Exhaust from a Diesel Generator

Diesel fuel and diesel exhaust are known to be highly mutagenic partly because of the presence of polyaromatic hydrocarbons (PAHs) and their derivatives. The present study investigated the PAHs content in the diesel fuel fed to a diesel generator and also in the gas and particulate phase of generator emissions. Mutagenicity of the exhaust was also determined. Exhaust emissions were collected by a stack sampler: gas phase on XAD-2 resin while particulate phase on glass fibre thimble. PAHs were characterized by a gas chromatograph by using a flame ionization detector. The low molecular weight PAHs dominated in the fuel, whereas the high molecular weight PAHs dominated in the exhaust with a greater emission factor in the particulate phase. The results reveal the pyrosynthesis of high molecular weight PAHs during the combustion process. Emissions also increased with increase in load. Extract of exhaust emissions were positive in both Salmonella typhimurium tester strains TA 98 and TA 100 without metabolic act...

Assessment of Surface Ozone levels at Agra and its impact on Wheat Crop

Ozone is currently the most important air pollutant that negatively affects growth and yield of agricultural crops in most parts of the world, and wheat is arguably the most important food crop in the Northern India. The higher ozone concentration in different regions is posing threat to food production. Measurement of surface ozone was made during the growing season (January-March 2011) of wheat crop at Agra. The daytime maximum was found to vary from 62–72 ppb and minima varied from 20–23 ppb. The effect of ozone on crop yield has been examined using exposure indices AOT40 and SUM06. The calculated AOT40 (2562 ppbh) and SUM06 (7470 ppbh) were found below the critical levels thereby indicating that wheat crop grown in Agra is safe from the threats of existing surface ozone levels.