Aerosol pH and Collection Efficiency Indicators from Aerosol Mass Spectrometry Measurements
Abstract
Aerosol sulfate composes an important fraction of submicron particulate matter (PM 1 ). However, recent research has indicated some analytical techniques have difficulty deconvolving the sulfate signal between organic (OS) and inorganic (e.g., ammonium-sulfate salts, AS) sulfate, which impacts our ability to understand how sulfate may impact various PM 1 intrinsic properties (e.g.,gas uptake, aqueous reactions). Inorganic sulfate measurements are also necessary for calculating aerosol pH with a thermodynamic model, as it is currently still challenging to measure the aerosol pH in-situ. Here, we use observations collected during major field campaigns (SEAC 4 RS, WINTER, KORUS-AQ, ATom-1, and ATom-2) and laboratory data to investigate the potential role of aerosol composition on recently proposed methods to deconvolve the total sulfate signal of Aerodyne Aerosol Mass Spectrometers (AMS) as AS or OS. In polluted areas with high ammonium nitrate concentrations (e.g., KORUS-AQ), and in areas with high acidity (remote regions, e.g. ATom-1 and ATom-2), the decomposition / fragmentation of sulfate changes, and is not amenable to retrieving OS concentrations. A relationship was found between the sulfate fragmentation patterns and AMS collection efficiency (CE, calculated using an established method), which potentially allows for an independent estimate of CE. Also, we found that the sulfate fragmentation patterns show a relationship with ambient aerosol acidity (pH). From this, a qualitative equation was created for a real-time, in-situ measurement of aerosol acidity.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A33P2914S
- Keywords:
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- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0340 Middle atmosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE