Fire/biomass burning

Process Burned or cleared area Biomass coverage (kg/m2) Total biomass cleared Biomass exposed to fire Biomass burned Above-ground biomass remaining unburned Carbon converted to CO + C02... 

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 ) ... 

Biofuels are used to create a wide variety of energy sources. Ever since the harnessing of fire, biomass has been used for heating and conking. Residential burning of biomass continues to be a primary source of fuel in less industrialized nations, but also has been used as fuel for electricity generation, and converted to liquid transportation fuels. 

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. 

Polycyclic aromatic hydrocarbons (PAHs, sometimes also called polynuclear aromatics, PNA) are a hazardous class of widespread pollutants. The parent structures of the common PAHs are shown in Fig. 4 and the alkylated homologs are generally minor in combustion emissions. PAHs are produced by all natural combustion processes (e.g., wild fires) and from anthropogenic activity such as fossil fuels combustion, biomass burning, chemical manufacturing, petroleum refining, metallurgical processes, coal utilization, tar production, etc. [6,9,15,18, 20,24,131-139]. 

Andreae MO, Adas E, Cachier H, Gofer WR III, Harris GW, Helas G, Kopp-mann R, Lacaux JR Ward DE, Trace gas and aerosol emissions from savanna fires, in Levine JS (ed.). Biomass Burning and Global Change, Vol. 1, MIT Press, Gambridge, MA, pp. 278-295, 1996. 

Global aerosol levels as measured by the Earth Probe, ADEOS, tfra/Nimbus-7 satellites can befound at this web address. Scientists use this data to observe a wide range of phenomena, such as desert dust storms, forest fires, and biomass burning. 

After release from fires, organic and some inorganic components undergo rapid or more delayed chemical transformation in the atmosphere. The physical properties as well as chemical composition of smoke particles may alter on the way from the source areas (biomass burning areas) to the measurement sites in Northern Europe. There are several reasons why particle properties change. Chemical components can, e.g., become oxidized or substituted in particles, but also the condensation of secondary material onto the LRT particles during the transport changes the particle properties. 

Many studies have shown that in North Europe major biomass burning emissions are mostly linked with wood smoke from fireplaces and stoves, whereas in Southern Europe wildfires can be the most important biomass combustion source. The Mediterranean region is frequently under the influence of this phenomenon, especially during dry periods. Although wildfires can be a major contributor of particulate matter into the atmosphere, forest fire emissions are poorly quantified in the literature, due to the difficulties induced in estimating their temporal and spatial distribution. 

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,... 

The contribution of savannah fires exceeds 40% of the global level of biomass burning as a result of which the atmosphere receives minor gas components, such as non-methane hydrocarbons, carbon monoxide, methane, etc., as well as aerosols. According to available estimates for the period 1975-1980, 40%-70% of savannahs were burnt every year, about 6% of such fires took place in Africa. In 1990 about 2 1091 of vegetable biomass were burnt, and as a result 145TgCO got into the atmosphere, which constituted about 30% of anthropogenic CO emissions. 

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