Abstract
Abstract. We report airborne measurements of emission factors (EF) for trace gases and PM2.5 made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to EF measured late in the African dry season they were at least 1.7 times larger for NOx, NH3, H2, and most non-methane organic compounds. Our measurements suggest that urban deposition and high windspeed may also be associated with significantly elevated NOx EF. When considering all fires sampled, the percentage of particles containing soot increased from 15 to 60 % as the modified combustion efficiency increased from 0.88 to 0.98. We estimate that about 175 Tg of fuel was consumed by open burning of biomass and garbage and as biofuel (mainly wood cooking fires) in Mexico in 2006. Combining the fuel consumption estimates with our EF measurements suggests that the above combustion sources account for a large fraction of the reactive trace gases and more than 90 % of the total primary, fine carbonaceous particles emitted by all combustion sources in Mexico.
Highlights
Biomass burning (BB) is the largest source of primary, fine carbonaceous particles and the second largest source of trace gases in the global atmosphere (Crutzen and Andreae, 1990; Bond et al, 2004)
Elemental carbon emission factors are based on thermo-optical, gravimetric measurements that isolate the mass of sp2-hybridized carbon
Soot is identified by its fractal shape and sp2-carbon bond peak in the electron energy-loss spectra (EELS) in the transmission electron microscope (TEM) and is believed to account for most, if not all, black carbon
Summary
Biomass burning (BB) is the largest source of primary, fine carbonaceous particles and the second largest source of trace gases in the global atmosphere (Crutzen and Andreae, 1990; Bond et al, 2004). Industrial and domestic burning of biomass as a fuel (biofuel) occurs globally and year-round; roughly proportional to population, but with much higher use per capita in developing countries (Yevich and Logan, 2003). The dry seasons in the NH tropics fall within the months of February–May; large amounts of open burning emissions are being produced somewhere on Earth in nearly every month. Less is known about the emissions from the significant amounts of open BB that occur in the NH tropics (i.e. Mexico, Central America, northern South America, the Sahel region of Africa, India, and Indochina, van der Werf et al, 2010)
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