Aerosol acidity and secondary organic aerosol formation during wintertime over urban environment in western India

作者：Rengarajan R^*; Sudheer A K; Sarin M M

来源：Atmospheric Environment, 2011, 45(11): 1940-1945.

DOI：10.1016/j.atmosenv.2011.01.026

• Urban aerosol
• Elemental and organic carbon
• Aerosol acidity
• Secondary organic aerosol

Atmospheric mass concentration of ambient PM2.5, its chemical composition and aerosol acidity have been studied during the wintertime from an urban site in a semi-arid region of western India. The concentration of PM2.5 ranged from 32 to 106 mu g m(-3) during the 30-day sampling period: and carbonaceous species (EC, OC) and water-soluble inorganic constituents (WSIC) account for similar to 58% and similar to 29% of the mass, respectively. The contribution of SO42- to PM2.5 is significant (Average: 17.5%) and that of NO3- is minor (Average: similar to 2%). The ratio of water soluble to particulate organic carbon (WSOC/OC) varies from 0.26 to 0.52 (Average: 0.41) and provides evidence for the significant role of secondary organic aerosol (SOA) in an urban environment. Measured concentration of [H+](air), used as an index of aerosol acidity, varies from 0.25 to 11 mu mol m(-3) and exhibits linear increase with the secondary organic carbon (SOC). Our field-based data provide the direct evidence for enhanced SOA formation at high level of acidity, consistent with laboratory studies.

• 出版日期2011-4