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Emissions from forest fires near Mexico City

Yokelson, R. J. and Urbanski, S. P. and Atlas, E. L. and Toohey, D. W. and Alvarado, E. C. and Crounse, J. D. and Wennberg, P. O. and Fisher, M. E. and Wold, C. E. and Campos, T. L. and Adachi, K. and Buseck, P. R. and Hao, W. M. (2007) Emissions from forest fires near Mexico City. Atmospheric Chemistry and Physics, 7 (21). pp. 5569-5584. ISSN 1680-7316. doi:10.5194/acp-7-5569-2007.

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The emissions of NO_x (defined as NO (nitric oxide) + NO_2 (nitrogen dioxide)) and hydrogen cyanide (HCN), per unit amount of fuel burned, from fires in the pine forests that dominate the mountains surrounding Mexico City (MC) are about 2 times higher than normally observed for forest burning. The ammonia (NH_3) emissions are about average for forest burning. The upper limit for the mass ratio of NO_x to volatile organic compounds (VOC) for these MC-area mountain fires was ~0.38, which is similar to the NO_x/VOC ratio in the MC urban area emissions inventory of 0.34, but much larger than the NO_x/VOC ratio for tropical forest fires in Brazil (~0.068). The nitrogen enrichment in the fire emissions may be due to deposition of nitrogen-containing pollutants in the outflow from the MC urban area. This effect may occur worldwide wherever biomass burning coexists with large urban areas (e.g. the tropics, southeastern US, Los Angeles Basin). The molar emission ratio of HCN to carbon monoxide (CO) for the mountain fires was 0.012±0.007, which is 2–9 times higher than widely used literature values for biomass burning. The ambient molar ratio HCN/CO in the MC-area outflow is about 0.003±0.0003. Thus, if only mountain fires emit significant amounts of HCN, these fires may be contributing about 25% of the CO production in the MC-area (~98–100 W and 19–20 N). Comparing the PM_(10)/CO and PM_(2.5)/CO mass ratios in the MC Metropolitan Area emission inventory (0.0115 and 0.0037) to the PM1/CO mass ratio for the mountain fires (0.133) then suggests that these fires could produce as much as ~79–92% of the primary fine particle mass generated in the MC-area. Considering both the uncertainty in the HCN/CO ratios and secondary aerosol formation in the urban and fire emissions implies that about 50±30% of the "aged" fine particle mass in the March 2006 MC-area outflow could be from these fires.

Item Type:Article
Related URLs:
URLURL TypeDescription
Yokelson, R. J.0000-0002-8415-6808
Atlas, E. L.0000-0003-3847-5346
Toohey, D. W.0000-0003-2853-1068
Crounse, J. D.0000-0001-5443-729X
Wennberg, P. O.0000-0002-6126-3854
Additional Information:© 2007 Author(s). This work is licensed under a Creative Commons License. Received: 19 April 2007. Published in Atmos. Chem. Phys. Discuss.: 16 May 2007 Revised: 14 August 2007, Accepted: 27 October 2007, Published: 9 November 2007. The authors thank Eric Hintsa and NSF for emergency supplemental funding that made it possible for ASU, U Miami, and U Colorado to conduct measurements on the Twin Otter. We thank the Twin Otter pilots E. Thompson, G. Moore, J. Stright, A. Knobloch, and mechanic K. Bailey. Special thanks go to S. Madronich, L. Molina, and J. Meitin for their dedication to making the MILAGRO campaign a success for all. The University of Montana, the planned fire, and the airborne research was supported largely by NSF grant ATM-0513055. Yokelson was also supported by the Rocky Mountain Research Station, Forest Service, U.S. Department of Agriculture (agreement 03-UV-11222049-046). The USFS science team and partial support for the airborne research was provided by the NASA North American Carbon Plan (NNHO5AA86I). Participation by Arizona State University was supported by NSF grant ATM-0531926. Electron Microscopy was performed at the John M. Cowley Center for High Resolution Microscopy at Arizona State University. Support to the University of Miami was provided by NSF (ATM 0511820). X. Zhu and L. Pope provided excellent technical support for the canister trace gas analyses. Support for operation of the Caltech CIMS instrument was provided by NASA (NNG04GA59G) and by EPA-STAR support for J. Crounse. We also thank the fire staff of Mexico’s Comision Nacional Forestal in the states of Morelos, Mexico, Distrito Federal, and the Guadalajara Headquarters for the execution of the prescribed fire in the state of Morelos and for logistical support to conduct post-fire assessment of several fires of opportunity flown by the Twin Otter aircraft. Edited by: L. Molina
Funding AgencyGrant Number
Rocky Mountain Research Station, US Forest ServiceUNSPECIFIED
Department of Agriculture (USDA)03-UV-11222049-046
NSFATM 0511820
Environmental Protection Agency (EPA)UNSPECIFIED
Issue or Number:21
Record Number:CaltechAUTHORS:20140702-135853774
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Official Citation:Emissions from forest fires near Mexico City R. J. Yokelson, S. P. Urbanski, E. L. Atlas, D. W. Toohey, E. C. Alvarado, J. D. Crounse, P. O. Wennberg, M. E. Fisher, C. E. Wold, T. L. Campos, K. Adachi, P. R. Buseck, and W. M. Hao Page(s) 5569-5584
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46643
Deposited By: Ruth Sustaita
Deposited On:02 Jul 2014 21:53
Last Modified:10 Nov 2021 17:29

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