Tracer-based source apportioning of atmospheric organic carbon and the influence of anthropogenic emissions on secondary organic aerosol formation in Hong Kong

Abstract. Here we conducted comprehensive chemical characterization and source apportionment of 49 PM2.5 samples collected in Hong Kong. Besides the major aerosol constituents, 39 polar organic species, including 14 secondary (SOA) tracers isoprene, monoterpenes, β-caryophyllene, naphthalene, were quantified using gas chromatography–mass spectrometry (GC–MS). Six factors, i.e., SOA, sulfate (SS), biomass burning (BB)/SOA, sea salt, marine vessels, vehicle emissions, apportioned by positive matrix factorization (PMF) as sources ambient carbon (OC) The formation, OC from SS, aging BB plume, was leading contributor to (51.4 %, 2.15 ± 1.37 µg C m−3) throughout year. We then applied a tracer-based method (TBM) estimate SOA formation photo-oxidation four selected precursors, monoterpene most abundant. A Kintecus kinetic model used examine channels isoprene aerosol-phase ring-opening reaction epoxydiols (IEPOXs) found be dominant pathway. Consistently, IEPOX contributed 94 % total GC–MS-quantified tracers. TBM-estimated (SOCTBM) PMF-apportioned SOC (SOCPMF) showed similar temporal trends; however, SOCTBM only accounted for 26.5 SOCPMF, indicating large fraction other pathways or precursors. Results Pearson's R multivariate linear regression analysis that NOx processing played key role both daytime nighttime production region. Moreover, had significant relationship with SOCPMF SS-related SOC, particle acidity significantly correlated BB.