HR: 0800h
AN: B51B-0362    [Abstracts]
TI: Speciation of Lead in Airborne Particulate Matter in El Paso, TX, by X-ray Absorption Spectroscopy
AU: * Pingitore, N E
EM: nick@geo.utep.edu
AF: The University of Texas at El Paso, Department of Geological Sciences, El Paso, TX 79968- 0555, United States
AU: Clague, J
EM: jclague@utep.edu
AF: The University of Texas at El Paso, Department of Geological Sciences, El Paso, TX 79968- 0555, United States
AU: Amaya, M A
EM: mamaya@utep.edu
AF: The University of Texas at El Paso, School of Nursing, El Paso, TX 79968, United States
AU: Olvera, H A
EM: holvera@utep.edu
AF: The University of Texas at El Paso, Department of Civil Engineering, El Paso, TX 79968, United States
AB: X-ray absorption spectroscopy indicates that lead humate is the dominant species of lead in airborne particulate matter in El Paso, Texas. Lead humate is a stable complex of Pb with the humus component of soil, and is the major Pb species that we found in El Paso soils. Because Pb-contaminated soil is the only significant source of lead humate, re-entrainment of such soil likely provides most of the lead found in particulate matter in the local atmosphere. Elimination of leaded gasoline dramatically decreased lead in particulate matter in the US over the last three decades. Consequently, there was a significant decrease in blood lead levels. Nonetheless, because Pb is such a potent neurotoxin for children, further reductions in airborne lead levels are being called for. Our result can inform this regulatory debate. We examined a total of 20 TSP (Total Suspended Particulate) samples collected at 3 stations in various seasons in 1999 and 2005. Low lead concentrations in the particulate matter and intimately associated filter medium compromised data quality. Six samples proved suitable for standard EXAFS analysis, and XANES analysis was possible with all 20. Comparisons of the XANES and EXAFS of our air samples indicated homogeneity of speciation with regard to geography, season, and year. The XANES and EXAFS spectra were a close match to those of both a lead humate standard and a typical El Paso soil sample with an elevated lead level. X-Ray absorption spectroscopy experiments were conducted at the Stanford Synchrotron Radiation Laboratory on beam lines 7-3, 10-2, and 11-2. Spectra were collected at the Pb L-III absorption edge in fluorescence mode using a 13-element or a 30-element Ge solid-state detector. This publication was made possible by grant numbers 1RO1-ES11367 and 1 S11 ES013339-01A1 from the National Institute of Environmental Health Sciences (NIEHS), NIH. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, NIH. Partial travel support provided by SSRL-DOE-UTEP Gateway Program.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0432 Contaminant and organic biogeochemistry (0792)
DE: 0461 Metals
DE: 0478 Pollution: urban, regional and global (0345, 4251)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting