Source apportionment of polycyclic aromatic hydrocarbons in urban atmosphere of South Delhi, India

Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous persistence organic pollutants (POPs). Several PAHs are known toxic, mutagenic and carcinogenic compounds. Understanding the contributions of the various emission sources is critical to appropriately managing PAH levels in the environment. In the present study, PM10 samples were collected at two sampling sites (UA and CR) in Delhi during the period of monsoon and winter season from July 2013 to January 2014. The concentrations of 10 selected PAHs in aerosols were quantified for source apportionment analysis. Their total amount at CR ranged from 18 to 161 ngm-3 whereas at UA it varies from 15 to 116 ngm-3. The sources of PAHs in Delhi were determined by using source apportionment methods (molecular diagnostic ratios). At CR, vehicular emissions in the form of diesel and gasoline exhaust were major emission sources. On the contrary, mixed type of sources (coal combustion, wood combustion and gasoline and diesel engine emissions) were the contributor of particulate PAHs at UA in Delhi. The results clearly indicate that the major PAHs emission sources in the Delhi are traffic emission, coal combustion, and wood combustion related sources. These sources are responsible for high levels of PAHs which draws attention towards immediate measures for PAHs control in Delhi.

Keywords: PAHs; Source apportionment; Diagnostic ratio; Delhi