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CHEMICAL ANALYSIS METHODS FOR ATMOSPHERIC AEROSOL COMPONENTS
Citation:
Solomon, P A., G A. Norris, M S. Landis, AND M P. Tolocka. CHEMICAL ANALYSIS METHODS FOR ATMOSPHERIC AEROSOL COMPONENTS. Chapter 11, Aerosol Measurements. Van Nostrand Reinhold Company Incorporated, New York, NY, (2001).
Impact/Purpose:
The core aerosol research for FY01 includes evaluation of newly developed and developing methods for the chemical analysis and sampling of PM in ambient air, especially state-of-the-art continuous and non-invasive aerosol measurement methods, and the study of the aerosol sampling processes to better assess the true aerosol concentration and size distributions observed in the ambient environment. An additional emphasis is placed on integrated sampling for stable and semi-volatile organic aerosol species. This latter area addresses the state-of-the-art in this measurement area. This program supports Title I of the Clean Air Act in its mandate for performing research to support the NAAQS, GPRA goal 1.1.5, and ORD's main research objective on PM.
Much of this work directly supports OAQPS and may be applied within the Supersites Program managed jointly by OAQPS and ORD. This research also will support many of ORD's long-term research goals by providing more reliable information (decrease uncertainty) on ambient aerosols that can be utilized for characterizing risk.
Finally, an APM, has been established to develop measurement methods for causal factors, due in 2004. Currently, there are a number of causal factor hypotheses, but none have sufficient evidence to support developing one measurement/analytical method over another. The PM methods team will support and work with Joellen Lewtas on methods for the collection and analysis of semi-volatile and aerosol phase organic species to help address this APM. The PM methods team will continue to work within the Supersites program and with OAQPS and their new partners in ORIA to further evaluate continuous species specific methods and aerosol physical property measurement methods.
Description:
This chapter surveys the analytical techniques used to determine the concentrations of aerosol mass and its chemical components. The techniques surveyed include mass, major ions (sulfate, nitrate, ammonium), organic carbon, elemental carbon, and trace elements. As reported in the literature, there are wide variations in the chemical composition of the aerosol and their concentrations, thus, requiring application of several analytical methods to obtain valid data. Over the last decade, determination of organic aerosol species in ambient particulate matter has become feasible. Availability of this type of detailed organic aerosol data have greatly enhanced the ability of receptor models to identify sources (Schauer et al. 1996; Schauer and Cass 2000). Thus, analytical methods to determine organic aerosol species are described in this chapter. Finally, semi-continuous species-specific methods, are rapidly emerging that could eliminate the need to collect aerosols on filters with retrospective chemical analysis in the laboratory. These methods are becoming available for sulfate, nitrate, other anions and cation species, OC, EC, and trace elements. These methods are mentioned briefly at the end of this chapter.
The analysis method is only one aspect involved in determining the concentration of species in atmospheric particulate matter after collection of the sample on a filter or other substrate. Other issues include sample storage, where applicable, sample extraction from the filter, and quality control and quality assurance. Sample storage includes stabilizing the collected sample from the end of sampling through sample analysis. It also may include long-term storage to allow for reanalysis of the filter later. Finally, precision and accuracy of the measurements are needed to define uncertainty in data. These issues also will be briefly mentioned in this chapter.
The U.S. Environmental Protection Agency through its Office of Research and Development collaborated in the preparation of this review chapter. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.