Source Apportionment of VOCs in Pensacola, FL 2003

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Source Apportionment of VOCs in Pensacola, FL 2003

• Term paper for EAS6792/CEE6792
• Fall 2003
• Sangil Lee

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What VOCs can do.

• Ozone Formation
• NO2 hv NO O
• O O2 M O3 M
• O3 NO NO2 O2
• VOCs OH Organic Radicals
• Organic Radicals NO NO2
• Secondary Organic Aerosol Formation
• VOCs OH,O3,NO3 low volatile compounds
• condense on the available particles.
• Hazardous Air Pollutants

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Chemical Mass Balancereceptor model

• Quantify the source contribution to the receptor.
• Cik ?fijSjk i 1,n (chemical species)
• j 1,,m
  (sources), k 1,,l (samples).
• Cik observed conc. of species i in
  sample k.
• fij fraction of species i in
  source j.
• Sjk conc. of VOCs from source j in
  the sample k.
• Assumption 1) compositions of source emissions
  are constant, 2) chemical species do not
  react with each other, 3) all sources
  contributing significantly to the receptor have
  been included in the calculation, 4) the number
  of sources is less than or equal to the number of
  species, 5) the source profiles are sufficiently
  different from one another, 6) measurement
  uncertainties are random, uncorrelated, and
  normally distributed.

m
j 1
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Chemical Mass Balancereceptor model

• Source profiles diesel exhaust, gasoline
  exhaust, liquid gasoline, evaporated gasoline,
  refinery fugitives, industrial coating, primers
  enamel, printing (Watson et al., 2001).
• EPA CMB8 is used for the calculation.
• VOCs collected by using air canisters are
  analyzed by GC/FID at UC, Irvine.

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Measurement SitePensacola, FL
Measurement site
4 VOC samples collected per day (at 0700, 1200,
1700, 2300) from July 18 to Aug. 13, 2003
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Comparison between measured and Calculated
concentration
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Estimated Source Contribution
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Diurnal Pattern of Source Contribution
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Summary

• Calculated Concentrations agree with measured
  concentrations well.
• Gasoline (gasoline exhaust, evaporative gasoline)
  is a dominant source.
• Increased Conc. of VOCs at early morning
  midnight.
• CMB captures the diurnal pattern of biogenic
  emission.