title: Chemical characteristics of PM(2.5) at a source region of biomass burning emissions: evidence for secondary aerosol formation.
abstract: 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 SO4(2-)/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 SO4(2-) 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 (SO4(2-) + 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.
authors.affiliation: Geosciences Division, Physical Research Laboratory, Navrangpura, Ahmedabad 380009, India. Electronic address: nrastogi@prl.res.in.
authors.forename: N
authors.initials: N
authors.lastname: Rastogi
authors.forename: A
authors.initials: A
authors.lastname: Singh
authors.forename: D
authors.initials: D
authors.lastname: Singh
authors.forename: M M
authors.initials: MM
authors.lastname: Sarin
mesh_terms: D000336:Aerosols / Q000032:analysis; D000393:Air Pollutants / Q000032:analysis*; D018533:Biomass; D004784:Environmental Monitoring; D017745:Incineration; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter
keywords: Aerosol chemistry; Haze; India; Indo-Gangetic Plain; Paddy-residue burning; Transport