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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #301091

Title: Deriving simple empirical relationships between aerodynamic and optical aerosol measurements and their application

item MOORE, KORI - Utah State University
item MARTIN, RANDAL - Utah State University
item BRADFORD, WILLIAM - Campbell Scientific, Inc
item MARCHANT, CHRISTIAN - National Geospatial-Intelligence Agency
item JONES, DEREK - Utah State University
item WOJCIK, MICHAEL - Utah State University
item Pfeiffer, Richard
item Prueger, John
item Hatfield, Jerry

Submitted to: Journal of Environmental Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2014
Publication Date: 4/1/2015
Citation: Moore, K., Martin, R., Bradford, W., Marchant, C., Jones, D., Wojcik, M., Pfeiffer, R.L., Prueger, J.H., Hatfield, J.L. 2014. Deriving simple empirical relationships between aerodynamic and optical aerosol measurements and their application. Journal of Environmental Engineering. 141(4):04014078.

Interpretive Summary: Air quality is affected by the presence of particulates in the atmosphere; however, the measurement of particles has proven to be difficult especially when comparing different methods. The increased concern over the amount of particles in the air has caused a renewed emphasis on measurement methods which can be routinely used and produce reliable results. A study was undertaken to compare samples which measure the mass of particulates with an optical counter method covering a range of particle sizes. The mass and optical methods produce reliable results when compared to the federal reference method as the standard. The use of the secondary measurement methods for particulate sampling will produce acceptable results to compare among different management practices to reduce particulate loading in the atmosphere. These results benefit scientists working on methods to quantify particulate loading from different systems into the atmosphere.

Technical Abstract: Different measurement techniques for aerosol characterization and quantification either directly or indirectly measure different aerosol properties (i.e. count, mass, speciation, etc.). Comparisons and combinations of multiple measurement techniques sampling the same aerosol can provide insight into important relationships between the various methodologies and may also provide reliable and economic tools for greater spatial and temporal resolution in ambient particulate monitoring. A simple relationship referred to as a mass conversion factor (MCF), calculated from filter-based mass samples and optical particle counter (OPC) data, is herein described. The MCF is an on-site mass calibration for optically based measurements that can provide information about temporal and spatial mass concentration trends not possible from filter-based measurements. MCFs may be calculated for many mass fractions, such as PM2.5, PM10, or TSP. The MCF calculations have been performed on data collected during field measurements taken over a five-year period and results are herein summarized. Average and median values were 4.3 and 3.2 g cm-3 for MCF1, 5.0 and 3.2 g cm-3 for MCF2.5, 1.6 and 1.5 g cm-3 for MCF10, and 1.6 and 1.3 g cm-3 for MCFTSP. Pairwise comparisons from a collocated study with multiple OPCs and mass samplers suggest the minimum variability of the MCF is 5 to 10%, expressed as a relative standard deviation (RSD). The variability of the MCF within a sample period during a field study with arrayed samplers averaged 17 to 21%. In addition, the precision of the Airmetrics MiniVol Portable Air Sampler was found to be typically < 10% for PM through collocated tests. Comparisons with federal reference method (FRM) samplers showed that MiniVols yield PM2.5 concentrations essentially equivalent to FRMs with slightly greater deviations from the FRM for PM10.