The Northern Front Range Air Quality (NFRAQS) was the latest and most ambitious of a series of efforts to apportion sources of carbonaceous aerosol(soot) in the Dever, Colorado metropolitan area. The study was mandated by the Colorado State Legislature as a result of the continuing impact of aerosolcarbon on visibility in the region. Apportionments of fossil and biomass carbon was based on blank-corrected values of carbon mass concentrations (/m3)and 14C data (fM, fraction of modern) of field samples collected in downtown Denver. Over 100 14C measurements were made on size segregated (2.5/mdiameter) atmospheric aerosol samples collected during the summer of 1996 and the winter of 1996-1997. The reported fM values required correction forboth the mass and fM of the overall carbon blank. Lack of diredct fM data for these field blanks had a substantial effect on the estimated uncertainty ofthe final results and in the most extreme cases sample fM data had to be designated as **indeterminate.** Blank correction procedures and limitations willbe illustrated with quantitative data from the NFRAQS study.
Citation: Nuclear Instruments & Methods in Physics Research Section A-Accelerators Spectrometers Detectors and Associated Equipment
Pub Type: Journals
blank corrections, carbonaceous aerosols, NFRAQS, radiocarbon, source apportionment