出版社：Chinese Association for Aerosol Research in Taiwan
摘要：This study measured the carbonaceous aerosols in the atmospheric fine particulate matter (fPM; dia. < 2.5 µm, n = 102 samples) above an urban location (Prayagraj) on the central Indo-Gangetic Plain (IGP) for 1 year (December 2016–November 2017). During the study period, the fPM mass concentrations exhibited very high variability, ranging from 22 to 367 (avg. ± SD: 149 ± 87) µg m–3, and approximately 40% of the annual average consisted of carbonaceous aerosols (organic carbon [OC], water-soluble OC [WSOC], and elemental carbon [EC]). Furthermore, several diagnostic ratios (EC/fPM, OC/EC, char-EC/soot-EC, and WSOC/OC) indicated that the characteristics of the carbonaceous aerosols significantly differed between seasons, with emission sources, seasonal meteorology, and atmospheric chemistry driving the variation in abundance. Specifically, our trajectory analysis revealed an association between northwesterly air masses originating in northwestern India and higher concentrations of fPM and carbonaceous aerosols at the study site, which mainly occurred during the post-monsoon season and winter. However, anthropogenic emissions from local sources dominated the fPM and carbonaceous aerosols in summer and the monsoon season, during which we also observed the influence of air masses of mixed (continental/marine) origin. To identify the sources of the carbonaceous aerosols and evaluate their contributions, we analyzed the char-EC/soot-EC ratio in combination with the OC/EC ratio. Cross plots of these ratios identified biomass burning and fossil-fuel combustion as the largest sources during winter and the post-monsoon season, and summer and the monsoon season, respectively. Our results demonstrate the advantages of utilizing the char-EC/soot-EC ratio rather than the OC/EC ratio as a tracer of these two sources in the IGP region.
