Chemical characteristics of PM2.5 at a source region of biomass burning emissions: Evidence for secondary aerosol formation

Rastogi, N.; Singh, A.; Singh, D.; Sarin, M.M.

Chemical characteristics of PM2.5 at a source region of biomass burning emissions: Evidence for secondary aerosol formation

2014

Rastogi, N. | Singh, A. | Singh, D. | Sarin, M.M.

A systematic study on the chemical characteristics of ambient PM2.5, collected during October-2011 to March-2012 from a source region (Patiala: 30.2°N, 76.3°E; 250 m amsl) of biomass burning emissions in the Indo-Gangetic Plain (IGP), exhibit pronounced diurnal variability in mass concentrations of PM2.5, NO3−, NH4+, K+, OC, and EC with ∼30–300% higher concentrations in the nighttime samples. The average WSOC/OC and SO42−/PM2.5 ratios for the daytime (∼0.65, and 0.18, respectively) and nighttime (0.45, and 0.12, respectively) samples provide evidence for secondary organic and SO42− aerosol formation during the daytime. Formation of secondary NO3− is also evident from higher NH4NO3 concentrations associated with lower temperature and higher relative humidity conditions. The scattering species (SO42− + NO3− + OC) contribute ∼50% to PM2.5 mass during October–March whereas absorbing species (EC) contribute only ∼4% in October–February and subsequently increases to ∼10% in March, indicating significance of these species in regional radiative forcing.

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