Emissions of organic trace gases from savanna fires in southern Africa during the 1992 Southern African Fire Atmosphere Research Initiative and their impact on the formation of tropospheric ozone

Abstract

Abstract. CO, CH4, and organic trace gases were measured in air samples collected during several flights with a DC-3 aircraft through the plumes from savanna fires and agricultural fires during the SAFARI 92 campaign in southern Africa in September and October 1992. In all samples a variety of higher molecular weight organic compounds was found, most of which are very reactive. More than 70 of the roughly 140 major components present could be identified. Typically, mixing ratios of several hundred parts per billion carbon of organic compounds were measured inside the plumes, corresponding to an emission ratio of total organic carbon relative to CO2 of up to 1%. About 50% of these emissions were in the form of oxygenated and unsaturated compounds. The contributions of still unknown compounds to the total emission of organic compounds add up to another 20-30%. The observed emission ratios relative to CO2 show a considerable variation depending on the fuel type and the burning stages of the fire. The lowest value of the emission ratio of the sum of all identified organic compounds relative to CO2 was found for a sugar cane fire with (1.7 +_ 0.7) x 10 -3 (ppb C/ppb CO2). For a large savanna fire in Kruger National Park the ratio was (7.4 _+ 1.6) x 10 -3 (ppb C/ppb CO2). The highest value was (13.7 _+ 0.9) x 10 -3 (ppb C/ppb CO2) for an uncontrolled fire of mainly wood and shrub in the Drakensberg region. Results of model calculations show that in biomassburning plumes, reactive organic compounds contribute significantly to the formation of ozone, especially during the initial phase of photochemical processing.

Pre-Harvest Sugarcane Burning: Determination of Emission Factors through Laboratory Measurements

“…Le Canut et al [34] study examined pre-harvest burning practices [41] and Yokelson et al [24] and Lopes and Carvalho [35] made reference to the sugarcane pre-harvest burning practice as a broadly used method to separate dried leaves and weeds from the sugarcane and to eliminate pests that could hinder manual harvesting.…”

A review of biomass burning emissions part II: intensive physical properties of biomass burning particles

“…For example Forstner et al (1997) have shown that in a smog chamber, carbon yields from even the most reactive NMHC species is less than 5%. However, recent studies have shown that oxygenated hydrocarbons account for more than 40% of the non-methane hydrocarbon emissions by biomass burning (Koppmann et al, 1997). Due to their high reactivity, these species are typically unreported and could be a large reservoir for secondary aerosol production.…”

Atmospheric CH<sub>4</sub> and CO<sub>2</sub> enhancements and biomass burning emission ratios derived from satellite observations of the 2015 Indonesian fire plumes

“…A literature review of previous ground-and aircraft-based measurements of the CH 4 / CO 2 ER indicates a wide range of values, demonstrating the variability that can be dependent on not only the fuel type but also on additional factors, such as fuel moisture content, the ratio of living to dead matter and how recently the area last burned (Korontzi et al, 2003). To take just one example, Koppmann et al (1997) present CH 4 / CO 2 ER values for flaming fires of 2.6 ppb ppm −1 from sugar cane fields, increasing to 10.3 ppb ppm −1 over fires dominated by smouldering combustion in forest and shrubland. Fires with intermediate values were reported to represent a mixture of smouldering and flaming combustion.…”