OPEN JOURNAL OF ATMOSPHERIC AND CLIMATE CHANGE Temporal Changes in Particulate Matter and Trace Gas Concentrations: A Case Study of Delhi

The Study was conducted to understand the temporal changes in particulate matter and trace gases in different seasons using High Volume Sampler (HVS) from November 2005 to February 2008. Average suspended particulate matters (SPM), NO2 and SO2 concentration during the study period was 384±232, 33±15 and 15±7 µgm3 (excluding the dust storm events) respectively. The maximum concentration of SPM, NO2 and SO2 was 1968 (29 April 2006), 77 (18 August 2006) and 52 µgm3 (9 January 2008), whereas minimum concentration was 95 (26 September 2007), 9 (23 December 2005) and 2 µgm3 (18 March 2006) respectively. SPM concentration shows seasonal variation with highest concentration during summer 2006 (437±133 µgm3) followed by winter 2007-08 (433±131 µgm3) and monsoon 2007 (228±106 µgm3) irrespective of the fact that high winds and convective atmospheric conditions in summer encourages dispersion of particulates. During monsoon (rainy season), the washout of the pollutants by rains is the main reason for low SPM concentrations. A decreasing trend has been observed in concentration of SO2 in Delhi during last few years whereas concentration of NO2 has increased steadily in line with the increase in number of diesel vehicles. Keywords: SPM; SO2; NO2; High Volume Sample