HR: 16:00h
AN: A54A-01    [Abstracts]
TI: National Trends in Trace Metals Concentrations in Ambient Particulate Matter
AU: * McCarthy, M C
EM: mmccarthy@sonomatech.com
AF: Sonoma Technology, Inc., 1360 Redwood Way, Suite C, Petaluma, CA 94954, United States
AU: Hafner, H R
EM: hilary@sonomatech.com
AF: Sonoma Technology, Inc., 1360 Redwood Way, Suite C, Petaluma, CA 94954, United States
AU: Charrier, J G
EM: jcharrier@sonomatech.com
AF: Sonoma Technology, Inc., 1360 Redwood Way, Suite C, Petaluma, CA 94954, United States
AB: Ambient measurements of trace metals identified as hazardous air pollutants (HAPs, air toxics) collected in the United States from 1990 to 2006 were analyzed for long-term trends. Trace metals analyzed include lead, manganese, arsenic, chromium, nickel, cadmium, and selenium. Visual and statistical analyses were used to identify and quantify temporal variations in air toxics at national and regional levels. Trend periods were required to be at least five years. Lead particles decreased in concentration at most monitoring sites, but trends in other metals were not consistent over time or spatially. In addition, routine ambient monitoring methods had method detection limits (MDLs) too high to adequately measure concentrations for trends analysis. Differences between measurement methods at urban and rural sites also confound trends analyses. Improvements in MDLs, and a better understanding of comparability between networks, are needed to better quantify trends in trace metal concentrations in the future.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting