Atmosphere-Biosphere Interactions Toward a Better Understanding of the Ecological Consequences of Fossil Fuel Combustion (1981) / Chapter Skim
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3 Biogenic Emissions to the Atmosphere
3 Biogenic Emissions to the Atmosphere
Pages 22-34
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From page 22... ...
The biochemical mechanisms involved in the microbial generation of these gases vary markedly, however, and no generalization covers all of the volatile products or even any significant class of volatiles. NITROGEN Terrestrial Ecosystems Ecosystems consume atmospheric molecular nitrogen (N2)
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From page 23... ...
The major factors that affect nitrous oxide emissions are nitrate content of the soil, oxygen status, moisture, pH, and temperature. It is generally believed that nitrous oxide is formed by the microbial reduction of nitrate or nitrite as microorganisms use these compounds for the terminal electron acceptor in their metabolism.
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From page 24... ...
Global estimates, based upon unfortunately few data, have been made by several individuals. The consensus has been that microbial action in soil is a major source of ammonia generated from the land surface but the size of estimates varies greatly.
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From page 25... ...
This makes it seem unlikely that most other large lakes, which are more oligotrophic, fix substantial amounts of N2, and lakes are probably minor participants in the global nitrogen cycle. A technical problem renders uncertain many quantitative estimates of nitrogen fixation in either terrestrial or aquatic systems.
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From page 26... ...
Regional data for aquatic ecosystems are too few to warrant global estimates. SULFUR Terrestrial Ecosystems It is generally accepted that soils are sources of volatile sulfur compounds.
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From page 27... ...
In fresh waters, production appears to be largely in anoxic hypolimnia or in sediments rich in organic matter. Measurements are too few to allow reliable regional or global estimates.
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Various mercuric compounds can be used as substrates, including inorganic compounds, elemental metal, and acetate (Rogers 1979, Hamilton 1972~. Several investigators have demonstrated that mercury in soil can be converted to volatile products.
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From page 29... ...
These emissions apparently are the result largely or entirely of the activity of microorganisms, and the processes are promoted if organic materials are added to the soil. The chief product appears to be dimethylselenide, although clime thyl diselenide may be formed from certain organic sulfur compounds, and hydrogen selenide is possibly emitted as well (Doran and Alexander 1977b)
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From page 30... ...
per year. Recent studies have raised interesting new questions concerning the influence that burning of biomass -- wood and other natural products excluding fossil fuels -- may have on global atmospheric budgets of certain trace gases such as CO2, CO, H2 J N2OJ NO, NO2 t and COS (Adams et al.
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From page 31... ...
31 Mercury Arsenic Air CH4 + / Water / CH3Hg+ \ ~ C2H.
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From page 32... ...
No estimates are available for total emissions from soils, fresh water s, or wetlands. Likewise, large uncertainties are associated with estimates of natural emissions of organic particulates.
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From page 33... ...
33 TABLE 3.1 Emissions of Major Pollutants from Residential Wood Combustion Wood-Burn~ng Stoves Fireplaces Grams per Pounds Percent- Grams per Pounds Percent Kilogram per 106 age Parti- Kilogram per 106 ageParti Chem~cal Species of Wood Btu curates of Wood Btu curates Carbon monoxide 160 22 22 3.0 (83-370)
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From page 34... ...
1 1a Ocean/freshwater 1.7 14 Biomass burning 3.5-46 1.6-7.1 Total ~830-880 ~15-21a aSoil-derived organics are mostly associated with large particles and are not included in the global budget. SOURCE: Adapted from Duce (1978)
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