Investigation of size distribution and mass characteristics of ambient aerosols and their combustion sources during post-monsoon in northern India

Özet

This study explores the size distribution and mass characteristics of ambient atmosphere in the source region ofbiomass burning (Punjab). The enhanced level of particulate matter (PM) concentrations were interpretedthrough measurements of number and mass concentration. MODIS (Moderate Resolution ImagingSpectroradiometer) fire count data and HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectorymodel) used to decipher the extent of burning activities and origin of air-masses, respectively. Significant diurnalvariabilities were observed in the PM1 (PM with aerodynamic diameter≤1 μm) and PM2.5 (aerodynamicdiameter≤2.5 μm) number and mass concentrations. Higher number (N0.3–2.5: 1.34 ± 0.20×104 #/cm3) andmass concentration (PM2.5: 286 ± 39 μg/m3, n=5) during nighttime compared to daytime (N2.5:0.74 ± 0.22×104 #/cm3; PM2.5: 224 ± 59 μg/m3, n=3) indicates impact of meteorological conditions (lowwind speed and shallower boundary layer height) and biomass (plausibly paddy) burning activity. Althoughpossibility of multiple sources and their varying strength (poor correlation between organic carbon (OC) andelemental carbon (EC)) can't be neglected, however, biomass burning appeared to be the dominant source (goodcorrelation (R2=0.4) between water-soluble potassium (K+) and PM) of ambient PM. Further, near similarnumber and mass size distribution of ambient and bio-fuels derived aerosols along with similar K+/PM and OC/EC ratio compared to that for paddy-residue burning imply that bio-fuel burning in the household kitchen couldbe the dominant contributor to enhanced PM concentration at sampling location in upwind IGP during the studyperiod.