ABSTRACT
Although continuous measurement methods for ambient particulate matter (PM) have advanced (Burtscher, 2002; McMurry, 2000; Solomon and Sioutas, 2008; Wang et al., 2009; Watson et al., 1998; Wexler and Johnston, 2008), sampling through size-selective inlets onto †lter media with subsequent laboratory analysis is still the most widely applied method for PM characterization
7.1 Introduction .......................................................................................................................... 179 7.2 Filter Sampling ..................................................................................................................... 180 7.3 Sample Processing ................................................................................................................ 182 7.4 Laboratory Analyses ............................................................................................................. 186
7.4.1 Filter Weighing Gravimetry for Mass ...................................................................... 186 7.4.2 Light Transmission/Absorption (babs) Analysis as a Black Carbon Surrogate ......... 186 7.4.3 X-Ray Fluorescence Analysis for Elements ............................................................. 187 7.4.4 Inductively Coupled Plasma-Mass Spectrometry Analysis
for Elements and Isotopes ......................................................................................... 187 7.4.5 Ion Chromatography Analysis for Anions and Cations ............................................ 188 7.4.6 Automated Colorimetry Analysis for Ammonium ................................................... 189 7.4.7 Atomic Absorption Spectrophotometry Analysis for Monoatomic Cations ............ 189 7.4.8 Thermal/Optical Analysis by Reªectance and Transmittance
(TOR and TOT) for Organic and Elemental Carbon ............................................... 189 7.4.9 Thermal Analysis for Water-Soluble Organic Compounds ...................................... 190 7.4.10 High-Performance Liquid Chromatography-UV/Vis
for Three Major WSOC Classes ............................................................................... 191 7.4.11 IC with Pulsed Amperometric Detector Analysis for Carbohydrates
and IC with Conductivity Detector Analysis for Organic Acids .............................. 191 7.4.12 Thermal Desorption-Gas Chromatography-Mass Spectrometry Analysis
for Nonpolar Organic Compounds ........................................................................... 192 7.4.13 Computer-Controlled Scanning Electron Microscopy for Single-Particle
Morphology and Composition .................................................................................. 192 7.4.14 Data Management and Validation ............................................................................ 194
7.5 Summary and Conclusions ................................................................................................... 195 Acknowledgments .......................................................................................................................... 195 References ...................................................................................................................................... 195
(Watson and Chow, 2011). PM †lter analyses are used to identify and quantify source contributions (Watson and Chow, 2005, 2007; Watson et al., 2002, 2008), estimate visibility impairment (Watson, 2002), evaluate adverse effects on human health (Mauderly and Chow, 2008; Pope and Dockery, 2006), and determine causes of material damage (Hu et al., 2009a,b). PM concentrations for mass, elements, water-soluble ions, and organic and elemental carbon (OC and EC, respectively) are measured on †lters acquired at ∼400 sites in urban and nonurban U.S. networks (Flanagan et al., 2006; Hansen et al., 2006; Watson, 2002). More useful information could be obtained from these and other †lter samples at a small incremental cost. Source samples acquired by dilution sampling systems (ASTM, 2008; Deuerling et al., 2010; England et al., 2007a,b; Hildemann et al., 1989) are also amenable to the same measurements described here and are becoming more in demand for multi-pollutant air quality management strategies (Chow and Watson, 2011; Chow et al., 2010a; Hidy and Pennell, 2010).
