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ABSTRACT: The temporal variation of ambient SO2 and the chemical composition of particulate matters (PM2.5 and PM10) were studied at National Physical Laboratory (NPL), New Delhi (28°38′N, 77°10′E). Spatial variation of SO2 at seven air quality monitoring stations over Delhi was also studied simultaneously. Wide range of ambient SO2 was recorded during winter (2.55 to 17.43ppb) compare to other seasons. SO2 mixing ratio was recorded significantly high at industrial sites during winter and summer; however, no significant spatial
difference in SO2 mixing ratio was recorded during monsoon. SO42−/(SO2+SO42−) ratio was recorded high (0.74) during winter and low (0.69) during summer. Monthly variation of PSCF was analyzed using
HYSPLIT seven days backward trajectories and daily average SO2 data. PSCF analysis suggests that, during winter (December, January, February) ambient SO2 at the study site might have contributed from long distance sources, located towards west and southwest directions; during
monsoon (July, August, September) marine contribution was noticed; whereas, during summer (April, May and June) it was from
regional sources (located within few 100km of study site). During winter there was significant contribution from the long
distance sources located in western Asia, northwestern Pakistan, Rajasthan and Punjab provinces of India. Coal used in thermal
power plants at Panipat (in the northwestern side) and Faridabad (in the southeastern side), local industries, soil erosion
and biomass burning may be major contributing factors for SO2 during summer. The study establishes that the transport sector may not be the major source of ambient SO2 in Delhi.
KeywordsSeasonal variation–Ambient SO2
–Aerosols (cations and anions)–Meteorological parameters
Journal of Atmospheric Chemistry 04/2012; 65(2):127-143. · 0.99 Impact Factor
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ABSTRACT: We present diurnal variation of ambient ammonia (NH3) in relation with other trace gases (O3, CO, NO, NO2, and SO2) and meteorological parameters at an urban site of Delhi during winter period. For the first time, ambient ammonia (NH3) was monitored very precisely and continuously using ammonia analyzer, which operates on chemiluminescence method. NH3 estimation efficiency of the chemiluminescence method (>90%) is much higher than the conventional chemical trapping method
(reproducibility 4.5%). Ambient NH3 concentration reaches its maxima (46.17ppb) at night and minimum during midday. Result reveals that the ambient ammonia
(NH3) concentration is positively correlated with ambient NO (r
2 = 0.79) and NO2 (r
2 = 0.91) mixing ratio and negatively correlated with ambient temperature (r
2 = − 0.32). Wind direction and wind speed indicates that the nearby (~500m NW) agricultural fields may be major source of
ambient NH3 at the observational site.
Environmental Monitoring and Assessment 04/2012; 162(1):225-235. · 1.40 Impact Factor
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Journal of Environmental Sciences 01/2010; 22:1023-1028. · 1.66 Impact Factor
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Environmental Monitoring and Assessment 01/2010; 162:225-235. · 1.40 Impact Factor
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ABSTRACT: We present the diurnal and seasonal variability of ambient NH3, NO, NO2 and SO2 over Delhi, India. Ambient NH3, NO and NO2 were measured continuously during winter, summer and autumn seasons using NH3- and NOx-analyzer, which operates by chemiluminescence method with a higher estimation efficiency (> 90%) than the chemical trap method (reproducibility 4.7%). Prominent diurnal, day-to-day and seasonal variations of ambient mixing ratio of NH3, NO, NO2 and SO2 were observed during the study period. Seasonal variation with higher mixing ratio in winter was observed for all measured trace gases except NO. Day-night variation of all measured trace gases observed was higher in winter in comparison with summer. Late morning increase in NO2 mixing ratio might be attributed to conversion of NO to NO2 with the interaction of O3.
Journal of Environmental Sciences 01/2010; 22(7):1023-8. · 1.66 Impact Factor
