AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Characterization of Re-suspended Soil Dust Samples from Sources Common in the Desert Southwest United States
ANDREA CLEMENTS, Matthew Fraser, Nabin Upadhyay, Pierre Herckes, Paul A. Solomon, Arizona state University
Abstract Number: 471 Working Group: Source Apportionment
Abstract The performance and accuracy of many atmospheric source apportionment models is sensitive to representative and accurate source characterization. When it comes to a soil source signature, some source appointment studies rely on chemical source profiles for soil that were generated from samples outside the study area, many do not try to differentiate between soil type or land-use, and occasionally source profiles are not size specific. As a result, the use of profiles in the source-apportionment studies can have serious drawbacks due to representativeness issues. This might lead to an under- or over-estimate of the soil dust contribution to atmospheric particulate matter (PM).
During a recent atmospheric particulate matter characterization and source apportionment study conducted in Pinal County, Arizona, numerous samples were collected from regional dust sources including paved and unpaved roads, agricultural soils, native (undisturbed desert), and material from within a cattle feed lot. Samples were collected during several seasons. Each sample was re-suspended in the laboratory followed by collection of PM10 and PM2.5 to obtain a more accurate representation of aerosol re-entrainment by particle size. Samples were chemically characterized for bulk organic and elemental carbon content as well as for more specific markers including water-soluble ions, elements, and organic species including alkanes, organic acids, polycyclic aromatic hydrocarbons, and saccharides.
Results from this work show uniform composition of most crustal elements between PM10 and PM2.5 samples. Comparison with upper continental crust, a common surrogate for crustal material, shows several important compositional variations. As one example, arsenic is elevated in all samples consistent with water and soil samples from the desert southwest. Comparison with local native desert samples elucidates marker species that can be used to differentiate between different land use types.