AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Performance Evaluation of a Recently Developed Aerosol Chemical Speciation Monitor (ACSM)
Neel Kotra, VISHAL VERMA, Jiumeng Liu, Sri Hapsari Budisulistiorini, Wendy Marth, Jason Surratt, Eric Edgerton, Karsten Baumann, Eladio Knipping, Stephanie Shaw, Nga Lee Ng, Rodney Weber, Georgia Institute of Technology
Abstract Number: 326 Working Group: Instrumentation and Methods
Abstract Both epidemiological and toxicological studies have found the associations between ambient particulate matter (PM) and adverse health outcomes. Recent studies have also linked PM toxicological characteristics to their chemical composition, such as organic and inorganic species. Since most of these studies rely on the statistical associations between PM constituents (or their sources) with the health effects; an accurate measurement of the ambient levels of these components is of crucial importance for establishing the appropriate cause-effect relationships.
The Aerosol Chemical Speciation Monitor (ACSM) is a recently developed instrument for measuring the atmospheric PM1.0 composition [non-refractory organic and inorganic ions such as sulfate, ammonium, nitrate, and organic matter (OM)]. The data collected from this instrument has also been used in the source apportionment studies by applying advanced analysis techniques (e.g. positive matrix factorization; PMF); however very limited studies have been conducted to compare its results with the other established methods of measurements. This study provides an intercomparison of the performance of a newly purchased ACSM (Aerodyne Research Inc.) with other online methods, such as Ion-chromatography (IC) coupled with a Particle-Into-Liquid-Sampler (PILS), thermal-optical OC EC analyzer (Sunset Labs), thermal sulfate (Thermo Scientific Sulfate Particulate Analyzer), and a denuder difference method for nitrate. Measurements were made at two sites in Atlanta and during three different seasons (Fall, Winter/Spring, and Summer) in preparation for use of the ACSM in a larger EPA-supported field campaign (SCAPE). Overall, there was a good correlation among measurements (R2 > 0.80) from all instruments with variability in the ratios of ACSM’s measurements with respect to other instruments. For example, OM/OC ratios varied from 1.6 in Fall to 2.5 in Winter. For inorganic ions, ACSM was lower for both sulfate (>10 %) and ammonium levels (>5 %), but higher for the nitrate levels (>20 %). These comparison results are important from the perspective of validating ACSM data, and their application in the source apportionment and health related studies. The sources of this variability in the PM component levels from different measurement techniques will be further explored and presented.