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Particulate carbon is a major component of PM2.5.
Major reasons to measure particulate carbon are assessment of its impact on global climate, health, visibility,
and source apportionment. Many methods were developed since the mid 1970's. Today, the thermal optical volatilization
techniques are used most commonly. Examples are IMPROVE used since 1987 for the National Parks Service's visibility
network and STN for the USEPA's Speciation Trends Network. Both techniques use thermal volatilization with optical
correction for charring. The differences in the temperature profiles (ramping rates, plateaus, and dwell times),
and charring correction approaches (laser reflectance for IMPROVE and laser transmittance for STN) result in differences
in evolved carbon fractions and EC. Our research has showed that aggressive temperature ramps in the OC phase in
STN can result in oxidation of particulate EC by in-situ metal oxides, and that charring of the adsorbed organic
vapor in the filter can influence the charring correction by transmittance. Some of these adsorbed compounds include
n-alkanes (C23-C31), hopanes (C27-C31), and n-alkanoic acids (C10-C22) (Sihabut et al, 2005). As the extent of
charring is affected by the nature of the compounds, their concentrations present, and the rate of heating, transmittance
correction is affected by the internal charring. On the other hand, reflectance only monitors the charring due
to the particles on the filter surface and thus is unaffected by the temperature profile used.
Agreement of carbon fractions from different analyzers depends on the accuracy of sample temperatures and the level
of trace oxygen in the system. We developed a temperature calibration procedure to audit thermal optical carbon
analyzers so that sample temperatures would be correctly indicated by the oven sensor. At ~40 ppm or higher of
trace oxygen, some changes in the carbon fractions were observed, but the OC/EC split was not be affected due to
charring correction.
Other applications of the analyzer include determination of carbonates (to assess the impact of yellow sand in
China, for example) and water soluble organic compounds to estimate secondary organic aerosols. |
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| Kochy Fung, Ph.D. received his B.S. in chemistry from U.C.L.A. and his Ph.D. in pharmaceutical chemistry
from the University of Southern California. Dr. Fung has over 35 years of research experience in several fields,
with the most recent 29 years in the environmental areas. After working 12 years for an environmental consulting
firm (ERT, later as ENSR), he founded AtmAA, an environmental laboratory with a partner and Atmoslytic Inc. for
instrumental development. He has conducted over 50 gaseous and particulate monitoring programs, participating as
a principle investigator on the measurement of carbonyls and VOCs in major air quality studies in California, Houston,
and Northeastern United States. As the technical director in regional acid deposition monitoring programs: EPRI's
Operational Evaluation Network, and EPA's ACID MODES, and principle co-investigator in CARB's CADMP, he developed
many laboratory procedures to facilitate the monitoring. Many measurement techniques he pioneered are used currently
on a routine basis. Some examples are the DNPH method for carbonyls in ambient air, the TMO method for speciation
of particulate organic and elemental carbon, the use of passive organic vapor badges for the assessment of short
term exposures to ambient aromatic and chlorinated hydrocarbons, and the South Coast Method 25.3 adopted by the
USEPA as CTM Method 35 for the assessment of emissions from low VOC stationary sources such as IC engines, flares
and turbines. He has authored and co-authored many papers, and conducted presentations and workshops internationally. |
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| Judith C. Chow, Ph.D. is a Research Professor in the Division of Atmospheric
Sciences at Desert Research Institute (DRI), where she directs the Environmental Analysis Facility. Dr. Chow has
more than 28 years of experience in conducting air quality studies and performing statistical data analysis. She
is the principal author or co author of more than 242 peer reviewed publications, 361 presentations, and 192 technical
reports. She is the chair of the Editorial Review Board for the Journal of the Air & Waste Management Association,
co-editor-in-chief of Aerosol and Air Quality Research, and a member of the Editorial Review Board for TheScientificWorld.
Dr. Chow's service on prominent committees includes membership on the National Academy of Sciences/National Research
Council (NAS/NRC) Committee on Research Priorities for Airborne Particulate Matter. She is currently on the NRC
Board of Environmental Studies and Toxicology (BEST). Her other national committee experience includes the U.S.
Environmental Protection Agency (EPA) Clean Air Scientific Advisory Committee (CASAC) Ambient Air Monitoring and
Methods (AAMM) Subcommittee; the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate
Research Facility Science Board; the National Environmental Respiratory Center (NERC) External Scientific Advisory
Committee (ESAC); and the South Coast Air Quality Management District (SCAQMD) Multiple Air Toxics Exposure Study
III (MATES III). Dr. Chow earned MS and Sc.D. degrees in Environmental Science from Harvard University. She has
also been the principal investigator or major collaborator in more than 50 large air quality studies, including
the State of Nevada Air Pollution Study (SNAPS). |
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| John G. Watson, Ph.D. is a Research Professor in the Division of Atmospheric
Sciences at Desert Research Institute (DRI). Dr. Watson received his B.A. and M.S. in Physics and Ph.D. in Environmental
Sciences from Oregon Graduate Institute. He has over 30 years of experience in planning and conducting air quality
studies in the U.S. and internationally. Some of his professional activities include serving in National Research
Council (NRC) Committee on The Effects of Changes in New Source Review as the Topic Leader in Programs for Stationary
Sources of Air Pollutants (March 2004-February 23, 2006); Chair in National Academy of Engineering U.S. Committee
on Energy Futures and Air Pollution in Urban China and the United States, January 2005 - December 2006; Journal
of the Air and Waste Management Association Associate Editor (March 1, 2004-February 28, 2007) and Lecturer, Receptor
Model and Data Analysis Training Workshops (various sponsors) in Portland, OR; Las Vegas, NV; San Francisco, Sacramento,
Los Angeles, San Diego, and El Centro, CA; Pocatello, ID; Denver, CO; Phoenix and Tucson, AZ; Research Triangle
Park, NC; Pittsburgh, PA; Austin, TX; Chicago, IL Vancouver, B.C., Canada; Santiago, Chile; Taipei, Taiwan; and
Johannesburg, Cape Town; Pretoria, South Africa; and Mexico City and Cuernavaca, Mexico; A&WMA Publications
Committee (chair, 1998-2001), A&WMA Critical Review Committee (member, 1982-present; chair, 1995-1998); Intersociety
Committee on Methods of Air Sampling and Analysis (chair, 1995-present); and California Regional PM10/PM2.5 Regional
Air Quality Study Technical Committee. |
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For more information on this
Seminar please contact Paul Rieger at (626) 575-6876 or send email to: prieger@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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