Aerosol mass spectrometry has emerged as a powerful tool in the study of size and composition of submicron particulate matter, which has been recognized as a major concern for various environmental, health and climate problems. Over the past decade, the Aerodyne aerosol mass spectrometer (AMS) has been applied in various parts of the world for both ambient as well as laboratory-based studies in the characterization of particulate matter and the study of formation and transformation processes. Aerosol studies in Hong Kong have traditionally been based on filter sampling and off-line analysis, with real-time instrumentation having only been introduced in very recent years. This work presents the findings of three independent studies conducted with an aerodyne High-Resolution Time-of-Fligh...[ Read more ]

Aerosol mass spectrometry has emerged as a powerful tool in the study of size and composition of submicron particulate matter, which has been recognized as a major concern for various environmental, health and climate problems. Over the past decade, the Aerodyne aerosol mass spectrometer (AMS) has been applied in various parts of the world for both ambient as well as laboratory-based studies in the characterization of particulate matter and the study of formation and transformation processes. Aerosol studies in Hong Kong have traditionally been based on filter sampling and off-line analysis, with real-time instrumentation having only been introduced in very recent years. This work presents the findings of three independent studies conducted with an aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) in a first time application of online aerosol mass spectrometry in Hong Kong.

A month-long ambient sampling campaign was conducted in springtime 2011 at a suburban coastal site in Hong Kong to provide insights into the size-resolved chemical composition of non-refractory submicron aerosol species. Source apportionment of organic aerosol yielded three characteristic aerosol fractions with distinct temporal patterns. Backtrajectory analysis indicated an important influence of northerly coastal and continental air masses on particle mass loading and composition in Hong Kong.

Particle size information is established in the AMS by measuring particle flight times in vacuum conditions, as opposed to more commonly used electrostatic classification methods. A comparison study of the sizing capability of the AMS and two electrostatic classifier models (SMPS and FMPS, TSI models) using various mono- and polydisperse aerosol was conducted revealing a significant sizing disagreement between AMS and SMPS vs. the FMPS. A simple correction method was devised which could successfully reduce the observed discrepancy.

A major remaining source of uncertainty in mass quantification by the AMS is the so-called particle collection efficiency (CE). The influence of organic particle constituents on particle CE of inorganic particles was investigated and showed a significant effect with dependence on the organic and inorganic constituents of the particle.