Nitrous biomass burning

Globally, the oxides of nitrogen, NO (nitric oxide), NO2 (nitrogen oxide), and N2O (nitrous oxide), are key species involved in the chemistry of the troposphere and stratosphere. NO and N2O are produced mostly by microbial soil activity, whereas biomass burning is also an important source of NO. Nitric oxide is a species involved in the photochemical production of ozone in the troposphere, is involved in the chemical produaion of nitric acid, and is an important component of acid precipitation. Nitrous oxide plays a key role in stratospheric ozone depletion and is an important greenhouse gas, with a global warming potential more than 200 times that of CO2. 

Anderson I. C., Levine J. S., Poth M. A., and Riggan P. J. (1988) Enhanced biogenic emissions of nitric oxide and nitrous oxide following surface biomass burning. J. Geophys. Res. 93, 3893-3898. 

Let us use as an example one recent environmental case history relevant to petrochemicals production. Nitrous oxide (N2O) is implicated as a contributor to stratospheric ozone damage, and is also a potent greenhouse gas (Table 2.7). Recent work indicated that about 10% of the nitrous oxide contributions to the atmosphere was from the world s adipic acid plants, slightly more than the fraction contributed by biomass burning [31, 32]. It has been estimated that about 1 mol of N2O is produced per mole of adipic acid, or about 0.3 kg of N2O per kg of adipic acid. 

W.R. Cofer III, J.S. Levine, E.L. Winstead et al.. New Estimates of Nitrous Oxide Emissions from Biomass Burning, Nature (London), 349, 689-691 (1991). 

Atmospheric concentrations of nitrous oxide have increased about 13% over the last 200 years (NRC 2001). There are many sources for nitrous oxide, including microbial activity in soils, denitrification of fertilizers, biomass burning, fuel combustion, and even lightning strikes. 

High levels of indoor air pollutants result from the use of either open fires or poorly functioning stoves to bum biomass or coal (Ezzati Kammen, 2001). Women, especially those responsible for cooking, are the ones most heavily exposed. Young children who spend their time close to their mothers also have high exposures (Bruce et al., 2000). Many of the substances in smoke from either biomass or coal burning can be hazardous to humans. The most important are suspended particulate matter, carbon monoxide, nitrous oxide, sulfur oxides (coal), formaldehyde, and PAHs (Bruce et al., 2000 Smith et al., 2000). 

The samples are prepared as for elemental analyses and the moisture content of the sample has to be determined in parallel. The principle of enthalpy of combustion measurement consists of burning a sample in a pure oxygen environment and then measuring the temperature increase of the surrounding water bath [34,43,44]. The ignition is initiated by a copper wire, and the measurements are corrected for moisture content of biomass, nitrous and sulfuric acid formation. A complete description of the measurement instruction can be found in references [28,34]. 

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