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광주지역 블랙카본 에어로졸 입자의 오염원 기여도 평가

Source Apportionment of Black Carbon in PM2.5 Observed Using a Real-time Seven-wavelength Aethalometer at an Urban Site of Gwangju

Abstract 

In this study, light absorption coefficients of equivalent black carbon (eBC) in PM2.5 were observed for one year in 2019 using a real-time seven-wavelength aethalometer at an urban site of Gwangju to evaluate the contribution of fossil fuel (FF) combustion (BCFF) and biomass burning (BB) (BCBB) emissions to eBC concentration. The source apportionment of eBC was estimated using light absorption techniques, called the aethalometer model, which was proposed by Sandradewi et al. (2008). Daily average contribution of BCBB to eBC concentration ranged from 4 to 66%. The concentration of eBC was generally dominated by FF emission sources during the study period, but there were also cases in which the influence of BB was dominant in winter. A seasonal clear diurnal pattern in BCFF, which showed a sharp increase in the morning rush hour, then decreased, and showed a gradual increase in the evening rush hour, indicated that the diurnal variability of BCFF was associated with the typical hourly traffic volume change trend in urban areas. On the other hand, there was no clear variability except for autumn and winter, which showed a slight increase in the morning and afternoon, in the hourly variation of eBC due to seasonal BB emission. Results of filter-based measurements performed as a case study (May 1~June 12, 2019) indicated the hourly contribution of BCBB to BC during BB episode occurred at the site, in which 24-hr average OC, WSOC, K+, and Clconcentrations were highly enhanced, was in the range of 25~99% (a mean of 64%). Also the contribution of light absorption by brown carbon (BrC) particles to the total aerosol absorption at 370 nm wavelength ranged from 25 to 67%(a mean of 47%). However, the hourly contribution of BCBB to eBC for the periods when only the concentrations of OC and EC increased without increasing K+ and Cl- was in the range of 4~46% (a mean of 20%), suggesting that the measured eBC concentration at that period was strongly related to FF emissions. The contribution of BrC light absorption to the total aerosol absorption at 370 nm wavelength ranged from 10 to 30% (a mean of 20%). Results of the study suggest that it will be helpful in establishing a strategy to reduce BC particles emitted from urban areas. However, further modeling studies are needed to evaluate the effect of the reduction in the emission of BC particles in urban areas on the change in the concentration of PM2.5.

Key words 

Equivalent black carbon (eBC), Aethalometer model, BC source apportionment, Fossil fuel and biomass burning emissions

▶출처 : 한국대기환경학회지 제 38권 제 5 호, 2022.10 p.653-668