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NARSTO Workshop on Innovative Methods for Emission Inventory Development and Evaluation University of Texas, Austin October 14-17, 2003 |
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Implications on Contributing Sources by Chemical Composition in Regional Surficial Soil
H. García1, W.W. Li1, J. Walton1, R. Arimoto2 , C. Schoeesslin2, S. Sage2,
R. Okrasinski3, J. Greenlee3, W. Gutman3
1 Environmental Science and Engineering
University of Texas at El Paso (UTEP), El Paso, Texas, U.S.A.
2 Carlsbad Environmental Monitoring & Research Center (CEMRC)
New Mexico State University, Carlsbad, New Mexico, U.S.A.
3 Physical Sciences Laboratory (PSL)
New Mexico State University, Las Cruces, New Mexico, U.S.A.
The goal of the study was to chemically characterize Particulate Matter (PM) produced from presumptive sources of fugitive dust in the El Paso del Norte Region located on both sides of the U.S.-México border. Chemical analyses on 18 elements (As, Be, Cd, Cr, Co, Pb, Mn, Ni, Sb, Ag, Al, Ba, Ca, Cu, K, Mo, Na, and Zn) were conducted on soil samples collected at 18 sites during February 23-25, 2000 to provide chemical signatures for potential contributors to the dust load in the region. The samples were collected at eighteen sites during 23-25 February 2000, separated by size using sieves and a cyclone train, acid digested in a microwave, and analyzed by ICP-MS.
The application of Cluster and Principal Components Analyses consistently produced three groups of elements: (1) Ag-As-Cd-Cu-Mo-Pb-Sb-Zn; (2) Al-Ba-K-Ca-Co; and (3) Be-Cr-Mn-Ni, which explained 51%, 28% and 12% respectively of the data variance. A Redundancy Analysis demonstrated that: (1) distance to a smelter and size of the soil fraction were the main explanatory variables; and that (2) Ag, As, Ba, Cd, Mo, Mn, Na, Pb, Sb concentrations decreased with increasing distance from the smelter. Enrichment factors calculations, using Al as the reference element, indicated that the first group of elements had their highest enrichment factors on the fine size fraction, and that the second group of elements was associated with a crustal source.