AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
The Evaporation Loss of Fine Particles in the Multi-Filter PM10-PM2.5 Sampler (MFPPS)
CHUN-NAN LIU, Shi-Fan Lin, Chuen-Jinn Tsai, Naitional Chiao Tung University
Abstract Number: 244 Working Group: Aerosol Physics
Abstract Field studies were conducted at NCTU campus to determine the evaporation loss of fine particles (PM2.5) collected by the multi-filter PM10-PM2.5 sampler (MFPPS). A porous metal denuder (PMD) was installed in one of the channels of the MFPPS and used as a reference sampler for determining the evaporation loss. The MFPPS was collocated with a dichotomous sampler (Dichot, Andersen, Model SA-241), a WINS PM2.5 sampler (Thermo, Model 2000-FRM), and a tapered element oscillating microbalance with filter dynamic measurement system (TEOM-FDMS, Thermo, Model 1405-DF). Totally, twenty 24-h samples were obtained. Results show that during the sampling process, the evaporation in PM2.5 is severe, which ranges from 6.2 to 56.7 % in PM2.5 concentration and the percentage decreases with an increasing PM2.5 concentration. The evaporated concentration of NH4+, NO3- and Cl- accounts for 13.2 ± 10.7, 5.2 ± 4.9 and 2.2 ± 2.0 % in PM2.5 concentration, respectively, or 49.6 ± 19.5, 61.7 ± 23.6 and 79.5 ± 9.4 %, in the concentration of each species, respectively. After 24-h conditioning, PM2.5 concentration was decreased by 3.1 ± 3.6 %, which was calculated from the differences in inorganic ion concentrations obtained immediately after sampling and those after 24-h conditioning. If the filter samples were conditioned for over 24 hours, PM2.5 concentration was further decreased by 2.1 ± 2.83, 3.6 ± 4.04, 5.5 ± 5.7, and 6.9 ± 5.56 % after 48, 72, 96, and 120-h conditioning, respectively, compared to that after only 24-h conditioning. Based the TEOM-FDMS data, it can be concluded that the sampling artifact concentration determined by the PMD is underestimated by 13.8 ± 10.3 %, due to the lack of the artifact concentration of the particulate organic carbon (POC). In the future, the POC artifact will be determined by installing the VOC denuder in one of the sampling channels of the MFPPS.