Title: | Viscosity of alpha-pinene secondary organic material and implications for particle growth and reactivity |
Author(s): | Renbaum-Wolff L; Grayson JW; Bateman AP; Kuwata M; Sellier M; Murray BJ; Shilling JE; Martin ST; Bertram AK; |
Address: | "Department of Chemistry, University of British Columbia, Vancouver, BC, Canada V6T 1Z1" |
ISSN/ISBN: | 1091-6490 (Electronic) 0027-8424 (Print) 0027-8424 (Linking) |
Abstract: | "Particles composed of secondary organic material (SOM) are abundant in the lower troposphere. The viscosity of these particles is a fundamental property that is presently poorly quantified yet required for accurate modeling of their formation, growth, evaporation, and environmental impacts. Using two unique techniques, namely a 'bead-mobility' technique and a 'poke-flow' technique, in conjunction with simulations of fluid flow, the viscosity of the water-soluble component of SOM produced by alpha-pinene ozonolysis is quantified for 20- to 50-mum particles at 293-295 K. The viscosity is comparable to that of honey at 90% relative humidity (RH), similar to that of peanut butter at 70% RH, and at least as viscous as bitumen at =30% RH, implying that the studied SOM ranges from liquid to semisolid or solid across the range of atmospheric RH. These data combined with simple calculations or previous modeling studies are used to show the following: (i) the growth of SOM by the exchange of organic molecules between gas and particle may be confined to the surface region of the particles for RH = 30%; (ii) at =30% RH, the particle-mass concentrations of semivolatile and low-volatility organic compounds may be overpredicted by an order of magnitude if instantaneous equilibrium partitioning is assumed in the bulk of SOM particles; and (iii) the diffusivity of semireactive atmospheric oxidants such as ozone may decrease by two to five orders of magnitude for a drop in RH from 90% to 30%. These findings have possible consequences for predictions of air quality, visibility, and climate" |
Keywords: | Aerosols Air Pollutants Atmosphere Bicyclic Monoterpenes Climate Environmental Monitoring/methods Gases Monoterpenes/*chemistry Nitrogen/chemistry Oxygen/chemistry Ozone/chemistry Particle Size Solubility Temperature Viscosity Volatile Organic Compounds V; |
Notes: | "MedlineRenbaum-Wolff, Lindsay Grayson, James W Bateman, Adam P Kuwata, Mikinori Sellier, Mathieu Murray, Benjamin J Shilling, John E Martin, Scot T Bertram, Allan K eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2013/04/27 Proc Natl Acad Sci U S A. 2013 May 14; 110(20):8014-9. doi: 10.1073/pnas.1219548110. Epub 2013 Apr 25" |