AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Characterizing the Volatility of Near-road Submicron Organic Aerosols Near a North Carolina Interstate Freeway
PROVAT SAHA, Andrey Khlystov, Andrew Grieshop, North Carolina State University
Abstract Number: 543 Working Group: Urban Aerosols
Abstract Motor vehicles are a dominant source of primary and secondary submicron particulate matter (PM) in urban areas. There are steep gradients in concentrations of primary gas- and particle-phase species, including black carbon (BC), organic aerosols (OA) and other species within 10s to 100s of meters from the roadway. Here, we discuss a novel field measurement approach and preliminary data from an ongoing effort designed to improve our understanding of the dynamic nature of OA in near-road environments, derive a set of parameterizations to model the evolution of OA, and exposure concentrations in a near road environment.
A field study is designed for a site near Interstate 40 (I-40), outside of Durham, North Carolina which includes, (i) 4 weeks of continuous measurements in a near road regulatory monitoring station, located within 10 m from highway; (ii) one week intensive downwind transects measurements on a minor roadway perpendicular to I-40, running parallel to the dominant wind direction; and (iii) simultaneous intensive upwind background measurements from a stationary site. For high time resolution OA volatility measurement, a multi-channel thermodenuder (TD) system is developed and deployed at this field study which consists of four parallel lines those can be independently operated at various set temperatures and residence time conditions. A van is equipped for transects measurement with newly developed multi-channel TD, various aerosols (e.g., SMPS, ACSM, PAX, SP2) and gaseous (CO, NOx, O3) instruments and consecutively sample at different distances (10, 50, 100, 200 m) downwind of the highway and repeated several times a day. A set of volatility parameterizations (e.g., volatility distribution) is derived following the volatility basis set (VBS) framework from the measured OA volatility at different downwind distance from highway. Preliminary results from this study will be presented here. Result from this study will help us to model gas-particle partitioning of OA in a near road environment to better understand exposure to OA and other primary emissions in a near-road setting.