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

Carbonaceous aerosols at a suburban site in Indo-Gangetic plain

218-222Carbonaceous aerosols are emitted by combustion sources and may influence the climate by altering the radiation balance of the atmosphere. The carbonaceous component of the atmospheric aerosols is composed of two main fractions, viz. organic carbon (OC) and black carbon (BC). BC is emitted from the incomplete combustion while OC comes from the primary emission such as traffic exhaust and biomass burning and is also formed through atmospheric chemical conversion processes. Carbonaceous aerosols were monitored at a suburban site, Dayalbagh, Agra from January to October 2009 in the present study. It was found that total suspended particulate mass (TSPM) varied from 79 to 658 g m-3 with an average of 273±179.9 g m-3. Also, daily concentrations of OC and BC ranged from 20.4 to 147.4 g m-3 and from 1.4 to 20.3 g m-3 with the overall average concentrations of 60.9±40.5 g m-3 and 7.5±4.6 g m-3, respectively. OC/BC ratios indicate the emission sources of carbonaceous aerosols. When the OC/BC ratio exceeds 2.0, it indicates that carbonaceous aerosols mainly originate from secondary organic transformation. Daily average OC/BC ratio varied between 5.2 and 16.2 with an average of 8.1. To give an insight into the source contribution of OC and BC, correlation coefficient was determined. The correlation coefficient is found to be 0.79. This indicates that major fraction of OC and BC originates from a common source. Distinct monthly variation was observed in their concentrations

Comparison of BTX Profiles and Their Mutagenicity Assessment at Two

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 interspecies 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