title: Temporal trends in atmospheric PM₂.₅, PM₁₀, elemental carbon, organic carbon, water-soluble organic carbon, and optical properties: impact of biomass burning emissions in the Indo-Gangetic Plain.
abstract: The first simultaneous measurements and analytical data on atmospheric concentrations of PM(2.5), PM(10), inorganic constituents, carbonaceous species, and their optical properties (aerosol optical depth, AOD; absorption coefficient, b(abs); mass absorption efficiency, σ(abs); and single scattering albedo, SSA) from an urban site (Kanpur) in the Indo-Gangetic Plain are reported here. Significantly high aerosol mass concentration (>100 μg m(-3)) and AOD (> 0.3) are seen as a characteristic feature throughout the sampling period, from October 2008 to April 2009. The temporal variability in the mass fractions of carbonaceous species (EC, OC, and WSOC) is pronounced during October-January when emissions from biomass burning are dominant and OC is a major constituent (∼30%) of PM(2.5) mass. The WSOC/OC ratio varies from 0.21 to 0.65, suggesting significant contribution from secondary organic aerosols (SOAs). The mass fraction of SO(4)(2-) in PM(2.5) (Av: 12.5%) exceeds that of NO(3)(-) and NH(4)(+). Aerosol absorption coefficient (@ 678 nm) decreases from 90 Mm(-1) (in December) to 20 Mm(-1) (in April), and a linear regression analysis of the data for b(abs) and EC (n = 54) provides a measure of the mass absorption efficiency of EC (9.6 m(2) g(-1)). In contrast, scattering coefficient (@ 678 nm) increases from 98 Mm(-1) (in January) to 1056 Mm(-1) (in April) and an average mass scattering efficiency of 3.0 ± 0.9 m(2) g(-1) is obtained for PM(10) samples. The highest b(scat) was associated with the dust storm event (April 17, 2009) over northern Iraq, eastern Syria, and southern Turkey; thus, resulting in high SSA (0.93 ± 0.02) during March-April compared to 0.82 ± 0.04 in October-February. These results have implications to large temporal variability in the atmospheric radiative forcing due to aerosols over northern India.
authors.affiliation: Physical Research Laboratory, Ahmedabad, India.
authors.forename: Kirpa
authors.initials: K
authors.lastname: Ram
authors.forename: M M
authors.initials: MM
authors.lastname: Sarin
authors.forename: S N
authors.initials: SN
authors.lastname: Tripathi
mesh_terms: D000393:Air Pollutants / Q000737:chemistry; D001272:Atmosphere; D018533:Biomass; D002244:Carbon / Q000737:chemistry*; D004391:Dust; D017753:Ecosystem; D004784:Environmental Monitoring; D005390:Fires; D007194:India; D055620:Optical Phenomena; D052638:Particulate Matter / Q000737:chemistry*; D045483:Rivers; D013997:Time Factors; D014867:Water / Q000737:chemistry*; D014887:Weather; D014919:Wind
chemical_list: D000393:Air Pollutants; D004391:Dust; D052638:Particulate Matter; D014867:Water; D002244:Carbon