Figure 29: Time series plot comparing measured and calculated total [VOC] at OLC.
Figure 30: Scatter plot of measured vs. calculated [VOC] from Figure 29 data.
Figure 31: Comparison between measured and calculated concentrations of VOC species sampled at OLC on 4/29/2003 at 16:00 EST.
The source apportionment result indicates that 7 sources such as diesel exhaust, gasoline exhaust, evaporative gasoline, refinery fugitive, primers and enamel, and biogenic, including the experimentally determined flaming source from above, contribute to the [VOC] observed at the OLC site. Figure 32 shows a time series plot of the source contribution (fraction) to measured VOC, corresponding to the values in Table 24. The contribution from the flaming PB source was largest at night and early mornings with a maximum 15 % late night on March 10th, 2003. The majority of the observed VOC can be attributed to gasoline sources, followed by activities involving primers and enamel sources. The biogenic sources become more pronounced towards the end of the measurement period, approaching the middle of spring time, when the vegetation enters a more photosynthetically active period.
Figure 32: Source apportionment of VOC measured at OLC expressed as fractions (top), and as absolute concentrations in ppbC (bottom) for each of the 7 identified source categories.
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