Wintertime Particulate Matter in the San Joaquin Valley: Concentrations, Mechanisms, and Sources
This page finalized November 5, 2007
Chair’s Air Pollution Seminar
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Tuesday, November 20, 2007
10:00 a.m. - Noon
Sierra Hearing Room, Second Floor
1001 I Street, Sacramento
This
event is being Webcast, click here to view
Webcast viewers: Please send your
questions during broadcast to: sierrarm@calepa.ca.gov
Presentation is available at this link
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Wintertime Particulate
Matter in the San Joaquin Valley:
Concentrations, Mechanisms, and Sources
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Jorn Dinh Herner, Ph.D.,
Research Division
Air Resources Board
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The San Joaquin Valley in California has one of the most severe particulate air quality problems in United States.
During wintertime meteorological inversions trap pollutants near the surface and allow the buildup of particulate
matter near the surface. This seminar will present the results from field sampling that took place as part of the
California Regional PM10/2.5 Air Quality Study (CRPAQS) during the winter 2000/2001. Samples were collected using
filter-based methods, cascade impactors, and real time particle sizers. Samples were collected both in the San
Joaquin Valley and along the California Coast to determine local and transported PM. Size segregated chemical speciation
and modeling was used to infer sources and mechanisms of particle formation in the San Joaquin Valley.
The 24hr National Ambient Air Quality Standard for PM2.5 (particulate matter with aerodynamic diameter less than
2.5 µm) was exceeded by almost a factor of three during the study. PM2.5 was dominated by ammonium nitrate,
while the ultrafine fraction, PM0.1, was completely dominated by carbon species. Analysis of size and composition
of the size segregated ambient particulate matter suggest that two particle types exist in the San Joaquin Valley;
hygroscopic sulfate/ammonium/nitrate particles and less hygroscopic particles composed of mostly organic carbon
with smaller amounts of elemental carbon. These particle types exist separately in the atmosphere of the San Joaquin
Valley until coagulation mixes them in the accumulation mode. These findings have implications both when considering
exposure and strategies to reduce ambient PM levels in the San Joaquin Valley. |
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| Jorn Dinh Herner, Ph.D., works in the Research Division at the California Air Resources
Board (ARB). His research interests include ultrafine particulate matter found both in ambient and emitted from
combustion. Recent work at ARB include characterizing emissions from heavy duty diesel vehicles, especially the
effect of aftertreatment devices such as diesel particulate filters and NOx scrubbers. An additional interest is
laboratory sampling methodologies. As a graduate student Dr. Herner worked on the California Regional PM10/2.5
Air Quality Study (CRPAQS) analyzing the size and composition distribution of ambient particulate matter in the
San Joaquin Valley. Prior to his work on particulate matter Dr. Herner was employed in private industry remediating
contaminated groundwater. |
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For more information on this
Seminar please contact:
Peter Mathews at (916) 323-8711 or send email to: pmathews@arb.ca.gov
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For a complete listing of
the ARB Chairman's Series and the related documentation for each one of the series please check this page
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Main Seminar Series Page
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