Simpson, I. J. and Akagi, S. K. and Barletta, B. and Blake, N. J. and Choi, Y. and Diskin, G. S. and Fried, A. and Fuelberg, H. E. and Meinardi, S. and Rowland, F. S. and Vay, S. A. and Weinheimer, A. J. and Wennberg, P. O. and Wiebring, P. and Wisthaler, A. and Yang, M. and Yokelson, R. J. and Blake, D. R. (2011) Boreal forest fire emissions in fresh Canadian smoke plumes: C_1-C_(10) volatile organic compounds (VOCs), CO_2, CO, NO_2, NO, HCN and CH_3CN. Atmospheric Chemistry and Physics, 11 (13). pp. 6445-6463. ISSN 1680-7316 http://resolver.caltech.edu/CaltechAUTHORS:20110912-114757018
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Boreal regions comprise about 17% of the global land area, and they both affect and are influenced by climate change. To better understand boreal forest fire emissions and plume evolution, 947 whole air samples were collected aboard the NASA DC-8 research aircraft in summer 2008 as part of the ARCTAS-B field mission, and analyzed for 79 non-methane volatile organic compounds (NMVOCs) using gas chromatography. Together with simultaneous measurements of CO_2, CO, CH_4, CH_2O, NO_2, NO, HCN and CH_3CN, these measurements represent the most comprehensive assessment of trace gas emissions from boreal forest fires to date. Based on 105 air samples collected in fresh Canadian smoke plumes, 57 of the 80 measured NMVOCs (including CH_2O) were emitted from the fires, including 45 species that were quantified from boreal forest fires for the first time. After CO_2, CO and CH_4, the largest emission factors (EFs) for individual species were formaldehyde (2.1 ± 0.2 g kg^(−1)), followed by methanol, NO_2, HCN, ethene, α-pinene, β-pinene, ethane, benzene, propene, acetone and CH_3CN. Globally, we estimate that boreal forest fires release 2.4 ± 0.6 Tg C yr^(−1) in the form of NMVOCs, with approximately 41% of the carbon released as C_1-C_2 NMVOCs and 21% as pinenes. These are the first reported field measurements of monoterpene emissions from boreal forest fires, and we speculate that the pinenes, which are relatively heavy molecules, were detected in the fire plumes as the result of distillation of stored terpenes as the vegetation is heated. Their inclusion in smoke chemistry models is expected to improve model predictions of secondary organic aerosol (SOA) formation. The fire-averaged EF of dichloromethane or CH_2Cl_2, (6.9 ± 8.6) × 10^(−4)gkg^(−1), was not significantly different from zero and supports recent findings that its global biomass burning source appears to have been overestimated. Similarly, we found no evidence for emissions of chloroform (CHCl_3) or methyl chloroform (CH_3CCl_3) from boreal forest fires. The speciated hydrocarbon measurements presented here show the importance of carbon released by short-chain NMVOCs, the strong contribution of pinene emissions from boreal forest fires, and the wide range of compound classes in the most abundantly emitted NMVOCs, all of which can be used to improve biomass burning inventories in local/global models and reduce uncertainties in model estimates of trace gas emissions and their impact on the atmosphere.
|Additional Information:||© 2011 Author(s). Received: 2 March 2011. Published in Atmos. Chem. Phys. Discuss.: 22 March 2011. Revised: 17 June 2011. Accepted: 29 June 2011. Published: 7 July 2011. The ARCTAS mission was funded by the NASA Global Tropospheric Chemistry Program, the NASA Radiation Sciences Program, and the California Air Resources Board. The VOC research presented here was funded by NASA grant NNX09AB22G. The CH3CN measurements were supported by the Austrian Research Promotion Agency (FFG-ALR) and the Tiroler Zukunftstiftung, and were carried out with the help of T. Mikoviny, M. Graus, A. Hansel and T. D. Maerk. The HCN instrument was run by J. Crounse and A. Kuerten. We gratefully acknowledge the ARCTAS crew and science team, and the team of laboratory technicians and staff at UC-Irvine, especially B. Chisholm, R. Day, J. Glabe, G. Liu, B. Love, and A. Ly. We also thank E. Atlas (University of Miami) for updated alkyl nitrate calibrations, C. Wiedinmyer (NCAR) for help with the MODIS data acquisition, R. Hornbrook for helpful discussions, and two anonymous reviewers.|
|Official Citation:||Simpson, I. J., Akagi, S. K., Barletta, B., Blake, N. J., Choi, Y., Diskin, G. S., Fried, A., Fuelberg, H. E., Meinardi, S., Rowland, F. S., Vay, S. A., Weinheimer, A. J., Wennberg, P. O., Wiebring, P., Wisthaler, A., Yang, M., Yokelson, R. J., and Blake, D. R.: Boreal forest fire emissions in fresh Canadian smoke plumes: C1-C10 volatile organic compounds (VOCs), CO2, CO, NO2, NO, HCN and CH3CN, Atmos. Chem. Phys., 11, 6445-6463, doi:10.5194/acp-11-6445-2011, 2011.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||13 Sep 2011 22:14|
|Last Modified:||26 Dec 2012 13:40|
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