Volume 12, No. 4, August 2012, Pages 662-671 PDF(965 KB)
Impact of Nitrogen Oxides, Volatile Organic Compounds and Black Carbon on Atmospheric Ozone Levels at a Semi Arid Urban Site in Hyderabad
Y.V. Swamy1, R. Venkanna1, G.N. Nikhil1, D.N.S.K. Chitanya1, P.R. Sinha2, M. Ramakrishna1, A.G. Rao1
1 Indian Institute of Chemical Technology (IICT), Bioengineering and Environmental Centre, Hyderabad-500607, AP, India
2 Tata Institute of Fundamental Research (TIFR), National Balloon Facility, Hyderabad, AP, India
The surface level ozone (O3), nitrogen oxides (NOx = NO2 + NO), volatile organic compounds (VOCs), black carbon (BC) and meteorological parameters were continuously monitored for the period of one year (2010) at an urban site in Hyderabad using different trace gas monitors. The local emissions and meteorology have been found to play a significant role in diurnal variations of O3. The average peak time mixing ratios of O3 were observed in the range of 23 ± 8 to 67 ± 13 ppbv. Diurnal-seasonal variation of O3 and its precursors were also reported. The observed O3 concentrations were higher during the day than in the night. Maximum O3 concentrations in the three seasons i.e., summer, winter and monsoon were 56 ± 14 ppbv, 50 ± 9 ppbv, and 28 ± 10 ppbv, respectively. Weekday/weekend variation of O3 and its precursors were studied during the three seasons. High O3 concentrations were observed on weekends compared to weekdays, however, NOx and BC levels were found low during weekends. The weekend effect of O3 was high during winter. The annual average afternoon peak time O3 levels on weekends were 11% higher than the weekday concentrations. Weekday/weekend variations of NOx at morning traffic rush hour were 14%, 9% and 8% in winter, summer and monsoon, respectively. The annual mean of NOx and BC concentrations at weekend were observed to be lower than weekday about 10% and 9% respectively. VOC/NOx ratio is more (5) during weekend than weekday (4) which resulted in enhanced O3 formation.
Trace gas; Ozone; Volatile organic compounds; Black carbon; Meteorology and oxides of nitrogen.