Visibility impairing aerosols in the urban atmosphere of Delhi

Abstract

To study the visual air quality of Delhi, size fractionated aerosols - coarse and fine fractions of PM10 - were collected and analysed for SO4(-2), NO(-3), NH4+ and EC at three sites with different background activities. The analysed species constitute a smaller portion of coarse fraction (39%) but a larger portion of fine fraction (69%). The sampling was performed from June 2003 to November 2003 which covers monsoon and post monsoon seasons. Aerosol data was used to describe the spatial variation of Visibility Range as a function of chemical composition of visibility impairing aerosols. During the study period, visibility was found to be poor varying between 4.7 and 13 km with an average value of 9.4 km. It is observed that visibility impairment was more due to carbonaceous aerosol followed by sulphate.

Impacts of meteorological condition and aerosol chemical compositions on visibility impairment in Nanjing, China

“…Meanwhile, this value was also much lower than the measurement in Seoul under stagnant condition (603 Mm À1 , Kim et al, 2006) and in Delhi during summer and autumn seasons (644 Mm À1 , Singh et al, 2008).…”

“…In the eastern United States, sulfates were estimated to contribute most of the visibility degradation, whereas carbon aerosols contributed 35% of extinction as prescribed fire activity in the western United States (Malm and Day, 2000). On average, (NH 4 ) 2 SO 4 was the largest contributor to b ext in Jinan, Guangzhou, Xi'an and Brisbane Cao et al, 2012;Yang et al, 2007;Chan et al, 1999), while OM is highest contributor in Baoji, Xiamen, Beijing and Delhi (Xiao et al, 2014;Zhang et al, 2012a;Huang et al, 2015;Singh et al, 2008). Some studies from tropical and sub tropical countries also reported the organic matter as a major component in visibility impairing aerosols (Castanho and Artaxo, 2001;Lin and Tai, 2001).…”

Seasonal composition of remote and urban fine particulate matter in the United States

“…The importance of the role of aerosols in visibility degradation, climate change, and health effects is well known. Because of their ability to scatter and absorb solar radiation, aerosols degrade visibility in both remote and urban locations [e.g., Malm et al , 1994; Quinn et al , 2001, 2004; Brewer and Adloch , 2005; Tsai , 2005; Malm and Hand , 2007; Singh et al , 2008] and can have a direct effect on climate [e.g., Intergovernmental Panel on Climate Change ( IPCC ), 2007; Ramanathan and Carmichael , 2008; Kopp and Mauzerall , 2010]. Indirect effects on climate include their role in cloud processing and lifetime [e.g., Boucher , 1995; Williams et al , 2001; Lohmann and Feichter , 2005].…”

Regression Analyses between Recent Air Quality and Visibility Changes in Megacities at Four Haze Regions in China

“…Numerous studies around the world have focused on the relationship between visibility and aerosol composition (e.g., Dzubay et al, 1982;Sisler and Malm, 1994;Singh et al, 2008). In China, this relationship has also been widely investigated for individual cities.…”