AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Direct Measurement of Size Resolved Aerosol Acidity
REBECCA CRAIG, Peter Peterson, Ryan Dodson, Andrew Ault, University of Michigan
Abstract Number: 425 Working Group: Aerosol Chemistry
Abstract Aerosol acidity is an important parameter for assessing the impact of aerosol particles on climate, as many particle phase chemical processes are highly dependent on acidity, such as secondary organic aerosol formation and gas-particle phase partitioning. Particle acidity also affects aerosol chemical composition and hygroscopicity, which can influence cloud droplet nucleation and, ultimately, climate forcing. Disagreement between traditional methods for estimating aerosol pH and thermodynamic models used to predict aerosol pH calls for more refined techniques for direct measurement of aerosol acidity. Herein, we present a novel method for direct measurement of aerosol acidity using pH indicator. Aerosol particles are impacted onto pH indicator paper and the resulting color change of the paper is analyzed to determine pH. pH measurements of laboratory-generated standard aerosol particles shows a size dependent acidity trend, with aerosol acidity increasing with decreasing particle size. This result of non-uniform acidity within the atmospheric aerosol population could have implications for acidity-dependent particle phase processes.