4 research outputs found
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