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RADIOCARBON MEASUREMENTS ON PM-2.5 AMBIENT AEROSOL
Citation:
Lewis, C W., G. A. Klouda, AND W. D. Ellenson. RADIOCARBON MEASUREMENTS ON PM-2.5 AMBIENT AEROSOL. Presented at NARSTO 2000 Tropospheric Aerosols: Science and Decisions in an International Community, Queretaro, Mexico, October 23-26, 2000.
Impact/Purpose:
To use the tools of x-ray fluorescence (XRF), ion chromatography (IC), scanning electron microscopy (SEM), thermal optical (organic and elemental carbon -- OC & EC), and radiocarbon analysis combined with various receptor models to determine the contributions of sources to PM as measured in outdoor (ambient) environments or particular microenvironments involving human exposure issues.
Description:
Radiocarbon (14C) measurements provide an estimate of the fraction of carbon in a sample that is biogenic. The methodology has been extensively used in past wintertime studies to quantify the contribution of wood smoke to ambient aerosol. In summertime such measurements can provide an upper limit on the contribution of biogenic volatile organic compounds, through gas-to-particle conversion, to ambient PM-2.5 aerosol. Since this component of PM-2.5 is virtually uncontrollable, its quantification is important in the formulation of realistic overall control goals for summertime PM-2.5. Ambient PM-2.5 ambient samples have been collected during various large U.S. summertime field studies for subsequent radiocarbon analysis. Results will be reported for samples from Azusa, California (1997 Southern California Ozone Study) and Nashville, Tennessee (1999 Southern Oxidant Study).
This work has been funded wholly or in part by the United States Environmental Protection Agency under Interagency Agreement No. 13937923 to the National Institute of Standards and Technology, and Contract No. 68-D5-0049 to ManTech Environmental Technology, Inc. It has been subjected to Agency review and approved for publication.