AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Volatility of Material Coating Black Carbon Particles at Duke Forest, an Anthropogenically-influenced Forest Site in Southeastern USA
ANDREY KHLYSTOV, R. Subramanian, Desert Research Institute
Abstract Number: 602 Working Group: Aerosols, Clouds, and Climate
Abstract Secondary organic aerosol (SOA) from biogenic sources has a significant contribution to ambient aerosol loadings in Southeastern USA and thus contributes to adverse health effects of air pollution and influences regional and global climate. SOA can contribute to aerosol climate forcing via scattering and absorption of solar light. The latter could occur either when organic compounds absorb light by themselves (the so-called brown carbon) or by enhancing light absorption efficiency of black carbon (BC) when they coat BC particles. As part of a larger study to assess the effect of biogenic SOA on aerosol optical properties, a set of instruments, including scanning mobility sizers (SMPS), single particle soot photometer (SP2), and a thermodenuder, was deployed during June 2015 at a site in Duke Forest near Chapel Hill, NC. The site is characterized by a significant contribution of both biogenic and urban (mostly traffic) sources. Measurements of changes in aerosol volume and optical size upon heating in the thermodenuder at different temperatures are used to derive volatility properties of the ambient aerosol. A set of experiments using the tandem differential mobility analysis (TDMA) approach was carried out to investigate whether BC is internally or externally mixed with other aerosol constituents. We will discuss volatility properties of the bulk aerosol and the material that coats BC particles, as well as implications of external vs. internal mixing for derivation of bulk volatility properties of ambient aerosol.