http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Decker, Zachary C. J.,Zarzana, Kyle J.,Coggon, Matthew,Min, Kyung-Eun,Pollack, Ilana,Ryerson, Thomas B.,Peischl, Jeff,Edwards, Pete,Dubé,, William P.,Markovic, Milos Z.,Roberts, James M.,Veres, American Chemical Society 2019 Environmental science & technology Vol.53 No.5
<P>Biomass burning (BB) is a large source of reactive compounds in the atmosphere. While the daytime photochemistry of BB emissions has been studied in some detail, there has been little focus on nighttime reactions despite the potential for substantial oxidative and heterogeneous chemistry. Here, we present the first analysis of nighttime aircraft intercepts of agricultural BB plumes using observations from the NOAA WP-3D aircraft during the 2013 Southeast Nexus (SENEX) campaign. We use these observations in conjunction with detailed chemical box modeling to investigate the formation and fate of oxidants (NO<SUB>3</SUB>, N<SUB>2</SUB>O<SUB>5</SUB>, O<SUB>3</SUB>, and OH) and BB volatile organic compounds (BBVOCs), using emissions representative of agricultural burns (rice straw) and western wildfires (ponderosa pine). Field observations suggest NO<SUB>3</SUB> production was approximately 1 ppbv hr<SUP>-1</SUP>, while NO<SUB>3</SUB> and N<SUB>2</SUB>O<SUB>5</SUB> were at or below 3 pptv, indicating rapid NO<SUB>3</SUB>/N<SUB>2</SUB>O<SUB>5</SUB> reactivity. Model analysis shows that >99% of NO<SUB>3</SUB>/N<SUB>2</SUB>O<SUB>5</SUB> loss is due to BBVOC + NO<SUB>3</SUB> reactions rather than aerosol uptake of N<SUB>2</SUB>O<SUB>5</SUB>. Nighttime BBVOC oxidation for rice straw and ponderosa pine fires is dominated by NO<SUB>3</SUB> (72, 53%, respectively) but O<SUB>3</SUB> oxidation is significant (25, 43%), leading to roughly 55% overnight depletion of the most reactive BBVOCs and NO<SUB>2</SUB>.</P> [FIG OMISSION]</BR>
Zarzana, Kyle J.,Min, Kyung-Eun,Washenfelder, Rebecca A.,Kaiser, Jennifer,Krawiec-Thayer, Mitchell,Peischl, Jeff,Neuman, J. Andrew,Nowak, John B.,Wagner, Nicholas L.,Dubè,, William P.,St. Clair, American Chemical Society 2017 Environmental science & technology Vol.51 No.20
<P>We report enhancements of glyoxal and methylglyoxal relative to carbon monoxide and formaldehyde in agricultural biomass burning plumes intercepted by the NOAA WP-3D aircraft during the 2013 Southeast Nexus and 2015 Shale Oil and Natural Gas Nexus campaigns. Glyoxal and methylglyoxal were measured using broadband cavity enhanced spectroscopy, which for glyoxal provides a highly selective and sensitive measurement. While enhancement ratios of other species such as methane and formaldehyde were consistent with previous measurements, glyoxal enhancements relative to carbon monoxide averaged 0.0016 +/- 0.0009, a factor of 4 lower than values used in global models. Glyoxal enhancements relative to formaldehyde were 30 times lower than previously reported, averaging 0.038 +/- 0.02. Several glyoxal loss processes such as photolysis, reactions with hydroxyl radicals, and aerosol uptake were found to be insufficient to explain the lower measured values of glyoxal relative to other biomass burning trace gases, indicating that glyoxal emissions from agricultural biomass burning may be significantly overestimated. Methylglyoxal enhancements were three to six times higher than reported in other recent studies, but spectral interferences from other substituted dicarbyonyls introduce an estimated correction factor of 2 and at least a 25% uncertainty, such that accurate measurements of the enhancements are difficult.</P>