Volatile biomass burning

Nutrient Losses Associated With Biomass Burning. Nutrient losses associated with slash fires occur through volatilization and convective losses of ash. Elements with low temperatures of volatilization (e.g. N, K, S, and some organic forms of P) will be lost in the highest quantities (Table III) (57). Conversely, Ca and Mg have volatilization temperatures higher than that recorded during most vegetation fires. Almost all fire-induced losses of these elements are due to particulate transfer by convective processes. 

During biomass and fuel burning, a complex mixture of ill-characterized volatile organic matter are released into the atmosphere (Andreae and Merlet, 2001). It contributes to the formation of aerosols and fine particles of sizes up to 100 pm. After an estimated lifetime of 7.9 days (Cook and Wilson, 1996), they are either degraded or are removed from the atmosphere by precipitation. However, they can be transported a considerable distance. For example, boreal forest fires contribute substantially to atmospheric BC in the Arctic (Cook and Wilson, 1996), and Antarctica receives BC from biomass burning in the tropics (Wolff and Cachier, 1998). On a global scale the amount of atmospheric emission is estimated with 5-6Tg BC yr 1,... 

Barrefors G, Petersson G. 1995. Assessment by gas chromatography and gas chromatography-mass spectrometry of volatile hydrocarbons from biomass burning. J Chromatogr 710 71-77. 

According to Lobert et al. (1999), the sum of aU chlorine emissions from biomass burning is —7Tg(Cl)a. About 9% is emitted as CH3CI, less than 1% as other alkyl chlorides while the largest part is emitted as unspecified volatile inorganic and as particulate chlorine. 

Recent observations in controlled biomass burning experiments showed that less than 50% of volatile inorganic chlorine was in the form of HCl. Most appeared to be CI2 and HOCl and other alkaline reactive chlorine compounds (Keene et al., 2001). 

There are three prominent processes that release mercury of mixed natural and anthropogenic origin to the atmosphere. These three include biomass burning (deliberate and natural) and the evasion of mercury from soils and the ocean. The general factors controlling emission of mercury from soils have been discussed in the section on low-temperature volatilization. The mercury... 

Carbon is present in the atmosphere as CO2, CH4, CO, and volatile organic componnds (Table 5.2). Atmospheric CO2 concentration increased from 270 ppm (v/v) in 1850 to 360 ppm in 2000 (Figure 5.1). During the same period, CH4 concentration increased from 0.7 to 1.7 ppm. Mnch of the increase in CO2 is attributed to burning of fossil fuels since the indnstrial revolntion. However, a number of sources including natnral wetlands, rice paddies, livestock, termites, and biomass burning have been attributed to an increase in CH4 concentration of the atmosphere (Table 5.3). The total amount of CO2 in the atmosphere is estimated at about 735 Pg C (1 Pg = 10 g Pg = petagram), as compared to 3 Pg C for CH4. The amount of CO is estimated to be abont 0.2 Pg. Recent stndies have... 

Another part of NPP is lost by fires (biomass burning, see Chapter 2.6.4.5), by emission of volatile organic substances (VOC) and human use (food, fuel and shelter) loss of NPP (in 10 g C yr ) ... 

As part of the Megacity Initiative Local and Global Research Observations (MILAGRO) project, a comprehensive airborne study by Yokelson et al. reported the first detailed field measurements of biomass emissions in the Northern Hemisphere tropics [169]. Volatile emissions were measured from 20 deforestation and crop residue fires on the Yucatan peninsula. This included two trace gases which are often considered to be useful as indicators of biomass burning. One we have discussed before, namely acetonitrile, and the other is hydrogen cyanide. A variety of instrumentation was co-deployed for this investigation (FTIR spectroscopy, GD-FID, a GC-Trace Analytical Reduction Gas Detector, fluorescence and chemiluminescence instruments and various other spectrometers). PTR-MS was used to monitor methanol, acetonitrile, acetaldehyde, acetone, methyl ethyl ketone, methyl propanal, hydroxyacetone plus methyl acetate, benzene and 13 other volatile species. 

Karl, T. G., Christian, T. J., Yokelson, R. J. et al. (2007) The Tropical Forest and Fire Emissions Experiment method evaluation of volatile organic compound emissions measured by PTR-MS, EUR, and GC from tropical biomass burning. Atmos. Chem. Phys. 7 5883. 

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