Inorganic atmospheric compounds

In air, most arsenic particulates consist of inorganic arsenic compounds, often as As+3. Burning of coal and arsenic-treated wood, and smelting of metals are major sources of atmospheric arsenic contamination (i.e., >1 pg/m3). In general, atmospheric arsenic levels are higher in winter, due to increased use of coal for heating (Pershagen and Vahter 1979). 

Silicon is next to oxygen the most abundant element in the lithosphere the average content amounts about 30% by weight. Inorganic silicon compounds such as silica and silicates form the basis of most of the rocks forming the earth s crust. In the atmosphere, there is no silicon present, except as dust of cosmic and terrestrial origin. The silicon content in the hydrosphere, mainly in form of dissolved silica (silicic acid), is also very small. 

Sources of nitrogen atmospheric nitrogen, inorganic nitrogen compounds, or other derived nitrogen. 

Sulfur compounds are widespread in Nature in living organisms and this is also reflected in the geochemistry of sulfur. A constituent of amino acids (cysteine, methionine) and of cofactors such as biotin, thiamine, and coenzyme A, sulfur is essential for the maintenance of cells. Inorganic sulfur compounds, in the Earth s crust, the sea, and the atmosphere are converted by plants and microorganisms into organosulfur compounds, while the demands of animals and humans for sulfur is much lower and is usually met by the oxidation of amino acids. 

Schafer, P., Kreilein, H., Muller, M., and Gravenhorst, G. (1993). Cycling of inorganic nitrogen compounds between atmosphere and ocean in tropical areas off South East Asia. Mitt. Geol. -Paldont. Inst. Univ. Hamburg 76, 19—36. 

The amount of selenium contributed to the air by other sources is not known. Microbial action within the soil may also contribute selenium to the air (Fishbein 1983). Selenium biomethylation volatilizes about 3,000 tons of selenium per year into the atmosphere, which eventually returns to earth in rainfall (NAS 1976a). Volcanic gas is suspected to be the major natural source of atmospheric selenium. Certain plants metabolize inorganic selenium compounds to volatile selenium in the forms of dimethyl selenide (Lewis et al. 1971) and dimethyl diselenide (Evans et al. 1968). Animals are also capable of volatilizing selenium and releasing dimethyl selenide in expired air (Schultz and Lewis 1940). 

The nitrifying bacteria, universally found in aerobic soil and aquatic environments, derive energy from the oxidation of reduced inorganic nitrogen compounds (ammonia and nitrite). As do autotrophic bacteria, they obtain carbon from carbon dioxide in the atmosphere. 

Sulfur-oxidising bacteria convert inorganic sulfur compounds to sulfuric acid that can cause severe damage to mineral material. Thiobacillus species have been implicated with concrete corrosion in the Melbourne and Hamburg sewer systems due to sulfuric acid formation. However, a role in stone decay is less certain since sulfuric acid and calcium sulfate in stone can originate from the direct action of atmospheric pollution and acid rain. 

Graedel TE. 1978. Inorganic nitrogen compounds Emission and detection. In Chemical compounds in the atmosphere. New York, NY Academic Press, 19. 

Mercury Species in the Environment Most of the mercury encountered in water/ soil/sediments/biota (all environmental media except the atmosphere) is in the form of inorganic mercuric salts and orga-nomercurics. The presence of a covalent C—Hg bond differentiates organomercurics from inorganic mercury compounds that merely associate with the organic material in the environment but do not have the C—... 

As far as possible, the apparatus should have fused connections and contain a minimum of stopcocks. If this is not possible, special care should be taken in sealing all possible leaks. Drying tubes should be inserted between the apparatus and its connections to the pumps (vacuum) or to the atmosphere. Better still, liquid-nitrogen-cooled gas traps should be used to prevent entrance of atmospheric moisture. Since in the presence of HgO most inorganic D compounds exchange part of their D content for H, these precautions must be observed in all reactions described in later sections. 

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