| Water uptake by atmospheric particles alters particle properties, such as size, shape, and composition. Understanding particle water uptake is necessary for determining the influence of atmospheric aerosol on climate and photochemistry, as well as for estimating particle dose to respiratory airways. This study uses theoretical and modeling approaches (verified with data where possible) to improve understanding of water uptake by atmospheric particles in general, with special focus on dust particles in particular. The main contributions are as follows: (1) a method for calculating particle mutual deliquescence relative humidity (MDRH) from solubility data, (2) a theory for calculating the variation in MDRH with temperature for particles containing an arbitrary number of hydrated and anhydrous salts, (3) new water activity-concentration polynomials for highly supersaturated KCl, K 2SO4, KBr, and KNO3 solutions, (4) equilibrium calculations that provide bounds for heterogeneous reactions on dust particles, (5) improved understanding of how changes in dust composition due to heterogeneous reactions influence dust's ability to serve as cloud condensation nuclei, and (6) improved understanding of water competition in clouds due to dust aerosol. Results of this study have been incorporated into a leading aerosol model for use in estimating the effects of airborne particles on air quality and climate. |
