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RADIOCARBON MEASUREMENT OF THE BIOGENIC CONTRIBUTION TO SUMMERTIME PM 2.5 AMBIENT AEROSOL IN NASHVILLE, TN
Citation:
Lewis, C W., G. A. Klouda, AND W. D. Ellenson. RADIOCARBON MEASUREMENT OF THE BIOGENIC CONTRIBUTION TO SUMMERTIME PM 2.5 AMBIENT AEROSOL IN NASHVILLE, TN. ATMOSPHERIC ENVIRONMENT 38(35):6054-6061, (2004).
Impact/Purpose:
Develop and evaluate methods for the sampling and analysis of PM in ambient air, with emphasis on FRM/FEM for PMc, measurement of carbonaceous aerosols, measurement of biogenic aerosols, comparisons measurements from the STN and IMPROVE monitoring networks, and continuous methods for PM mass and its chemical components.
Description:
Radiocarbon (14C) measurements performed on PM-2.5 samples collected near Nashville, TN from June 21 to July 13, 1999, showed high levels of modern carbon, ranging from 56 to 80% of the total carbon in the samples. Radiocarbon measurements performed on dichloromethane extracts of a subset of the samples showed modern carbon levels that were on average only 9% smaller than those for total carbon. A new approach based on the Chapman-Richards model of tree growth was used to define the quantitative relationship between measurements of 'percent modern carbon' and inferred 'percent biogenic carbon.' The results of this study contribute to a growing body of evidence (including measurements of radiocarbon, organic carbon to elemental carbon ratios and organic tracer species, as well as results from Chemical Mass Balance and air quality simulation modeling) in support of the importance of biogenic secondary organic aerosol (SOA) in the Southeastern U.S during summer.
The United States Environmental Protection Agency through its Office of Research and Development managed and partially funded the research described here under Contract 68D50049 to ManTech Environmental Technology, Inc., and Interagency Agreement DW13937923 to the National Institute of Standards and Technology, which also contributed to the funding. It has been subjected to Agency review and approved for publication. Certain commercial equipment, instruments, or materials are identified in this paper to specify adequately the experimental procedure. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials and equipment identified are necessarily the best available for the purpose.