1544 / 2019-08-18 19:52:46

Chemical differences between PM1 and PM2.5 and implications for severe haze formation in China

19、气溶胶与大气环境科学 > 专题2：气溶胶外场监测与污染机制解析

Aerodyne aerosol mass spectrometer (AMS) has been widely used for measurements of non-refractory aerosol species in submicron aerosols (PM1) during the past two decades. However substantial uncertainties remain when validating model simulations of PM2.5 aerosol species using the AMS measurements because of the large gap between 1 – 2.5 µm. In this work, we deployed a high-resolution time-of-flight AMS (HR-ToF-AMS) with PM1 lens and standard vaporizer, and two time-of-flight aerosol chemical speciation monitors (ToF-ACSMs) with PM2.5 lens and capture vaporizer in summer and winter in Beijing. Our results showed that the ratios of PM1 to PM2.5 varied differently for different aerosol species, and changed substantially across different pollution levels. Positive matrix factorization further illustrated the different ratios of primary and secondary organic aerosol in PM1 to PM2.5. Our results have significant implications that previous AMS measurements by missing the fractions of aerosol species in PM1-2.5 may have certain uncertainties in characterization of sources and evolutionary processes of severe haze pollution in winter in China.