Volcanic exhalation

The volcanic exhalations of today consist mainly of water and C02- There are good geological, geochemical and geophysical grounds for the assumption that today s exhalations are not much different than those produced around four billion years ago. However, we must assume that at that time there was very much more volcanic activity than today. 

A more oxidized state, in which the gases found today in volcanic exhalations were present. 

We know nothing of the pH value of the primeval ocean. However, the acidic character of volcanic exhalations must have meant that the young ocean was also... 

Ice has been found at the poles new measurements of Mars southern polar region indicate the presence of extensive frozen water. The polar region contains enough frozen water to cover the whole planet with a layer of liquid approximately 36 ft deep. A joint NASA-Italian Space Agency instrument on the European Space Agency s Mars Express spacecraft provided these data (NASA press release, 15 March 2007). It must be assumed that volcanic exhalations contained large amounts of water. 

Volcanic exhalations provide a great deal of the following starting materials for the synthesis of biomolecules H2O, CO2, CO, CH4, NH3 and sulphur compounds. 

There is no doubt that volcanic activity had various effects on the chemical processes occurring on the young Earth. Two articles deal with simulation experiments intended to study how volcanic exhalations may have affected prebiotic chemistry. 

The compound carbonyl sulphide (COS) is present today in volcanic exhalations ( 0.09 mol%). Since there was certainly much more volcanic activity on the young Earth than there is today, COS was then available in sufficient amounts for chemical reactions. As laboratory experiments show, amino acids can be linked under mild conditions to form peptides. 

PAHs in soil can be attributed to natural processes and human activities. Individual PAH concentrations in soils produced by natural processes like vegetation fires and volcanic exhalations have been estimated to be in the range of 1-10pgkg-1. Anthropogenic contribution has greatly affected the soil PAH concentrations. At present, even the lowest... 

Allard, P. (1992) The origin of hydrogen, carbon, sulfur, nitrogen and rare gases in volcanic exhalations Evidence from isotope geochemistry. In Forecasting Volcanic Events. H. Tazieff J. C. Sabroux, Eds., pp. 337-86. Amsterdam Elsevier. 

The chemical change produced in sea water by volcanic exhalations is mainly replacement of the hydrogen ions of acid gases dissolved in the water by ions of the alkaline-earth metals and alkali metals Na, Ca, and Mg (Zelenov, 1963). This process goes on more actively at high CO2 pressure. 

Although TES and THEMIS are sensitive to carbonates and sulfates, these minerals have not yet been detected unambiguously from orbit (Bandfield, 2002). The low carbon abundance in APXS-analyzed soils rules out much carbonate, although appreciable sulfur and chlorine are present in all soils. Thermodynamic stability considerations suggest that sulfates and iron carbonates should be present under martian conditions (Clark and Van Hart, 1981 Catling, 1999). It is unclear whether sulfate formed by reactions with acidic vapor from volcanic exhalations (Banin et al., 1997) or evaporation of surface brines (Warren, 1998 McSween and Harvey, 1998). 

Fig. 11-3. Geochemical cycles involving igneous and sedimentary rocks. The cycles are driven by the weathering action of atmospheric C02 dissolved in terrestrial surface waters, by the supply of C02 to the atmosphere from volcanic exhalations, and by the tectonic displacement of crustal material.

Fig. 12-3. Steady-state concentrations of N2, C02, CO, 02, H2, O, and OH in the prebiotic primitive atmosphere, according to model calculations of (Casting et al. (1979). These authors assumed a steady flux of H2 of 1012 m 2s 1 through the atmosphere, entering it by volcanic exhalations and leaving by Jeans escape.

The major sources of airborne anthropogenic arsenic are smelting of metals (mainly nonferrous metal production), burning of fossil fuels, and steel and cement production. The main natural emissions (possibly somewhat underestimated) are terrestrial volcanic exhalations and eruptions and submarine volcanism (Chilvers and Peterson 1987). Most trace metals are emitted on fine particles and thus can be... 

Suzuoki, T., A Geochemical Study of Selenium in Volcanic Exhalation and... 

Conclusions about the atmospheric composition of the early earth have been drawn from the gas exhalations of the so-called Hawaiian volcanoes type (Table 2.6). Oxygen is almost entirely missing from volcanic exhalations. Where O2 is... 

The composition of volcanic exhalations differs from volcano to volcano. There are dilferent ways of classifying volcanoes, but concerning the gases emitted, the classification by composition of material erupted (lava) is presented here ... 

Contrary to the air depletion by scavenging, the air was enriched relatively with insoluble N2 and less soluble compounds such as CO2 and H2S. As described later there is a continuous flux of CO2 through the oceans to the sediments converted as carbonate. Due to the low oxygen level, H2S remains in the atmosphere for the first half of the earth s history. Small amounts of SO2 from volcanic exhalations may have been in the air and in seawater after wet deposition. It is likely that... 

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