A Study on the Organic Aerosol Extinction Apportionment by Multiple Regression Model

In this study, the relationship between source of organic aerosol and particle light extinction (scattering, absorption) was investigated. The measurement site was Anmyeon Island (36.32°N, 126.19°E, altitude 45.7 m) located on the western coast of Korea. A total of fifty-nine daily PM2.5 samples were collected from June 2015 to May 2016 for every sixth day. A PM2.5 High volume air sampler (TE-5005BLX, Tisch Environmental, Inc., Ohio, USA) were installed on the roof and operated at a flow rate of 1.1 m³/min. Pre-baked quartz filters (TISSQUARTZ 2500QAT-UP, PALL life Science) were used for the sampling. The aerosol species for the analysis include black carbon (BC), humic-like substances (HULIS), water soluble organic carbon (WSOC) and water insoluble organic carbon (WISOC). The optical properties of organic aerosol including scattering and absorption are calculated based on the measurement data of WSOC, WISOC, EC, and HULIS and the positive matrix factorization model (PMF) was applied on these organic speciated data. Five source identification and apportionment (biogenic source, local biomass burning, secondary organic aerosol, transported biomass burning and the mixed sources) were considered from this model. Finally, an analysis of source apportionment to the scattering and absorption coefficients was performed by means of a multilinear regression (MLR) model. The results showed that the organic aerosol optical properties of Anmyeon Island are affected by regional and local sources and depend on aerosol size distribution as well as chemical species.