AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Radiocarbon Measurements of PM2.5 Total Carbon and Elemental Carbon from Centreville, AL during the SOAS Field Study
ERIC EDGERTON, Yanlin Zhang, Soenke Szidat, Andre Prévôt, Stephanie Shaw, John Jansen, Karsten Baumann, Charles Blanchard, Atmospheric Research & Analysis
Abstract Number: 507 Working Group: Air Quality and Climate in the Southeast US: Insights from Recent Measurement Campaigns
Abstract Radiocarbon (14C) analysis is a widely accepted technique for elucidating sources of carbon in aerosols. Recent advances have made it possible to analyze the 14C content of both total carbon (TC) and elemental carbon (EC) in aerosol samples, and, hence, calculate 14C for organic carbon (OC) by difference. Since EC is invariably produced by incomplete combustion processes, 14C data for EC permits new insights into relative contributions of mobile sources and biomass burning. This presentation will address 14C measurements on 23-hour duration PM2.5 samples collected during the SOAS campaign in Centreville, AL.
Samples for off-line chemical analysis were collected at Centreville, AL from June 1 to July 16, 2013. Twenty-three hour air samples (starting at 0800 each day) were collected on 8”x 10” pre-fired quartz (QMA) filters using a Tisch Environmental 6070 high-volume sampler equipped with a PM2.5 inlet. Samples were analyzed for 14C in TC and EC fractions following the procedure of Zhang et al., 2012. 14C(TC) is measured on carbon from an intact filter, while 14C(EC) is measured after aqueous extraction and thermal combustion in several steps for removal of OC.
Preliminary analysis of two 3-day composite samples collected early and late in the SOAS campaign show intriguingly high Fmodern for EC (i.e., 0.74 and 0.69). These values imply that roughly two-thirds of EC comes from biomass burning (BB). Given that BB produces much more OC than EC, these results also suggest non-negligible BB contributions to OC concentrations. Results from samples covering the entire campaign will be presented and BB contributions to TC, EC and OC will be discussed.