Size-resolved Chemical Composition of Aerosol Particles in Multiple Urban, Rural, and Remote Atmospheric Environments: an Integrated View Via Aerosol Mass Spectrometry

Qi Zhang University of California, Davis

Category: Aerosol Properties

Working Group: Aerosol Life Cycle

Size-resolved chemical composition of submicron particles in urban, urban downwind, high elevation, forested, coastal, and rural atmospheres was examined based on analyses of more than 30 ambient aerosol mass spectrometer data sets acquired from the Northern hemisphere. The size distributions of sulfate, nitrate, ammonium, and organics are summarized and compared among different types of environments. The size distributions of major types of organic aerosols (OA), e.g., hydrocarbon-like and oxygenated OA (HOA and OOA), were extracted via multivariate analysis of the size distributions of main OA fragments, e.g., m/z’s 44, 43, 55, and 57. These components are evaluated according to correlations with secondary inorganic aerosol species (e.g., sulfate and nitrate) and primary emission tracers such as elemental carbon, CO, and NOx. The HOA component in urban locations usually consists of an ultrafine mode and an accumulation mode that overlaps with those of OOA and sulfate. The size distributions of OOA and sulfate are overall similar; both are usually dominated with an accumulation mode that centers around 450–600 nm. Compared to that of sulfate, the size distribution of OOA tends to be slightly broader, extending more into the small size mode. The broader OOA size distribution is more obvious during periods when semi-volatile OOA (SV-OOA) is an important component of OA, which is consistent with surface-controlled partitioning of semi-volatile species. In addition, case studies will be conducted to evaluate the influence of new particle formation and growth events on the total and chemically resolved size distributions. The evolution of the size distributions of different aerosol species will also be examined for prominent particle growth cases.

http://www.envtox.ucdavis.edu/Faculty_Personal_Web_Pages/zhang/AMS_global_database.html

This poster will be displayed at ASR Science Team Meeting.