Multi-instrument comparison and compilation of non-methane organic gas emissions from biomass burning and implications for smoke-derived secondary organic aerosol precursors
Multiple trace-gas instruments were deployed during the fourth Fire Lab at Missoula Experiment (FLAME-4), including the first application of proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOFMS) and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/17/1471/2017/acp-17-1471-2017.pdf |
| Summary: | Multiple trace-gas instruments were deployed during the
fourth Fire Lab at Missoula Experiment (FLAME-4), including the first
application of proton-transfer-reaction time-of-flight mass spectrometry
(PTR-TOFMS) and comprehensive two-dimensional gas
chromatography–time-of-flight mass spectrometry (GC × GC-TOFMS) for
laboratory biomass burning (BB) measurements. Open-path Fourier transform
infrared spectroscopy (OP-FTIR) was also deployed, as well as whole-air
sampling (WAS) with one-dimensional gas chromatography–mass spectrometry
(GC-MS) analysis. This combination of instruments provided an unprecedented
level of detection and chemical speciation. The chemical composition and
emission factors (EFs) determined by these four analytical techniques were
compared for four representative fuels. The results demonstrate that the
instruments are highly complementary, with each covering some unique and
important ranges of compositional space, thus demonstrating the need for
multi-instrument approaches to adequately characterize BB smoke emissions.
Emission factors for overlapping compounds generally compared within
experimental uncertainty, despite some outliers, including monoterpenes.
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Data from all measurements were synthesized into a single EF database that
includes over 500 non-methane organic gases (NMOGs) to provide a
comprehensive picture of speciated, gaseous BB emissions. The identified
compounds were assessed as a function of volatility; 6–11 % of the total
NMOG EF was associated with intermediate-volatility organic compounds
(IVOCs). These atmospherically relevant compounds historically have been
unresolved in BB smoke measurements and thus are largely missing from
emission inventories. Additionally, the identified compounds were screened
for published secondary organic aerosol (SOA) yields. Of the total reactive
carbon (defined as EF scaled by the OH rate constant and carbon number of
each compound) in the BB emissions, 55–77 % was associated with compounds
for which SOA yields are unknown or understudied. The best candidates for
future smog chamber experiments were identified based on the relative
abundance and ubiquity of the understudied compounds, and they included furfural,
2-methyl furan, 2-furan methanol, and 1,3-cyclopentadiene. Laboratory study
of these compounds will facilitate future modeling efforts. |
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| ISSN: | 1680-7316 1680-7324 |