Volcanic emission

Sulfur forms several oxides that in atmospheric chemistry are referred to collectively as SOx (read sox ). The most important oxides and oxoacids of sulfur are the dioxide and trioxide and the corresponding sulfurous and sulfuric acids. Sulfur burns in air to form sulfur dioxide, S02 (11), a colorless, choking, poisonous gas (recall Fig. C.1). About 7 X 1010 kg of sulfur dioxide is produced annually from the decomposition of vegetation and from volcanic emissions. In addition, approximately 1 X 1011 kg of naturally occurring hydrogen sulfide is oxidized each year to the dioxide by atmospheric oxygen ... 

Bates et al. (1992) global total for volcanic emissions reapportioned as 1/3 continental and 2/3 marine. 

Pennisi M, Le Cloarec MF, Lambert G, Le Roulley JC (1988) Fractionation of metals in volcanic emissions. Earth Planet Sci Lett 88 284-288... 

Acid rain is actually a catchall phrase for any kind of acidic precipitation, including snow, sleet, mist, and fog. Acid rain begins when water comes into contact with sulfur and nitrogen oxides in the atmosphere. These oxides can come from natural sources such as volcanic emissions or decaying plants. But there are man-made sources as well, such as power plant and automobile emissions. In the United States, two-thirds of all the sulfur dioxide and one-fourth of the nitrogen oxides in the atmosphere are produced by coal-burning power plants. 

Cadmium (Cd) anode cells are at present manufactured based on nickel-cadmium, silver-cadmium, and mercury-cadmium couples. Thus wastewater streams from cadmium-based battery industries carry toxic metals cadmium, nickel, silver, and mercury, of which Cd is regarded the most hazardous. It is estimated that globally, manufacturing activities add about 3-10 times more Cd to the atmosphere than from natural resources such as forest fire and volcanic emissions. As a matter of fact, some studies have shown that NiCd batteries contribute almost 80% of cadmium to the environment,4,23 while the atmosphere is contaminated when cadmium is smelted and released as vapor into the atmosphere4 Consequently, terrestrial, aquatic, and atmospheric environments become contaminated with cadmium and remain reservoirs for human cadmium poisoning. 

The resulting CO2 gas is returned to the atmosphere by two means (1) volcanic emissions associated with eruptions near subduction zones, i.e., back-arc volcanoes or (2) diffusion through the sediments of the continental rise into the ocean, followed by gas exchange across the air-sea interfece. The combined production of CO2 from these two settings is thought to exceed that from the high-temperature hydrothermal reaction zones. 

The finding that the heterogeneous chemistry that occurs on polar stratospheric clouds also occurs in and on liquid solutions in the form of liquid aerosol particles and droplets in the atmosphere provided a key link in understanding the effects of volcanic eruptions on stratospheric ozone in both the polar regions and midlatitudes. As discussed herein, the liquid particles formed from volcanic emissions are typically 60-80 wt% H2S04-H20, and hence the chemistry discussed in the previous section can also occur in these particles (Hofmann and Solomon, 1989). We discuss briefly in this section the contribution of volcanic emissions to the chemistry of the stratosphere and to ozone depletion on a global scale. For a brief review of this area, see McCormick et al. (1995). 

In addition to these indirect effects of volcanic emissions, there are a variety of nonvolcanic parameters that, of course, can change 03 as well, and these must be taken into account in assessing the role of the volcanic emissions alone. For example, there is a natural solar variability, part of which cycles on a time scale of about 11 years and part of which is on a much longer time scale (Lean, 1991 Lean et al., 1995a, 1995b Labitzke and van Loon, 1996). In addition, stratospheric ozone levels vary with the quasi-biennial oscillation (QBO), which is associated with a periodic variation in the zonal winds at the equator between 20 and... 

Long-term trends due to CFCs must also be removed from the data to examine the effects of volcanic emissions. Finally, one must take into account the possible contributions of air that has been processed through the polar vortices and of meteorological influences that are unique to certain locations (e.g., see Ansmann et al., 1996). 

Orpiment As2S3 Arsenosulfide Hydrothermal deposits, intrusive igneous rocks, volcanic emissions, hot springs, microbial precipitates... 

Arsenosulfides also include realgar, its polymorphs, alacrinite (AssSg), and amorphous forms of arsenic sulfide. Realgar and other forms of arsenic sulfide occur in hydrothermal deposits, some intrusive igneous rocks, volcanic emissions, and hot springs (Table 2.5). The bacterium, Pyrohaculum arsenaticum, also biologically precipitates realgar at temperatures of 68-100°C (Nordstrom and Archer, 2003), 12. 

Quiseft, J.P., Toutain, J.P., Bergametti, G. et al. (1989) Evolution versus cooling of gaseous volcanic emissions from Momotombo Volcano, Nicaragua thermochemical model and observations. Geochimica et Cosmochimica Acta, 53, 2591-608. 

The fact that sulfur is often found in areas of volcanic activity may be due to the reaction of sulfur dioxide, S02, and hydrogen sulfide, H2S, both gases being found in volcanic emissions. One such reaction can be represented by the equation... 

In addition to gaseous species in the atmosphere, there are solid and liquid particulates as well. These are known as aerosols and their sizes vary from micrometers to millimeters. Sea salt, dust, and volcanic emissions are natural sources of aerosols. Figure 4.4 illustrates the sizes of some particulates in the atmosphere. 

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