Comment on egusphere-2026-3647

Résumé fourni par la source

Abstract. Secondary organic aerosol (SOA) is a major component of fine particulate matter, yet its molecular-level characterization remains challenging. Here, we systematically evaluated the performance of a Volatilization Inlet for Aerosols coupled with nitrate chemical ionization mass spectrometry (VIA-NO3-CIMS), including particle transmission, volatilization behavior, quantitative response, and operational stability. Following instrument characterization, the first field deployment of VIA-NO3-CIMS was conducted at the SORPES station in Nanjing, eastern China. A high-confidence dataset containing 1,695 particle-phase oxygenated organic molecules (OOMs) was established. The summed OOM concentration correlated strongly with AMS-derived organic aerosol concentrations (r = 0.88), demonstrating the quantitative capability of VIA–NO3–CIMS. Compared with gas-phase species, particle-phase OOMs exhibited larger carbon numbers, higher unsaturation, and lower volatility, with low-volatility compounds dominating the particle phase. Positive matrix factorization resolved seven SOA factors, including three biogenic-dominated, two anthropogenic-dominated, one regional background, and one pollution-episode factor. These factors contributed approximately 36.5 %, 35.4 %, 15.6 %, and 12.1 % of the total particle-phase OOM signal, respectively. Their molecular characteristics and temporal behaviors indicate important influences from daytime photochemistry, nighttime NO3 oxidation, regional transport, and episodic pollution accumulation. Factor contributions evolved systematically with PM2.5, with freshly formed SOA dominating under clean conditions and the pollution-episode factor becoming increasingly important as pollution levels increased, eventually dominating under the most polluted conditions. These results demonstrate that VIA-NO3-CIMS enables quantitative molecular-level characterization and source apportionment of particle-phase SOA, providing new insights into the composition and evolution of urban organic aerosols.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.