Geothermal vents

The current models of the Sun suggest that its luminosity would have been some 20-30 per cent lower than its present value during the early part of the formation of the Earth. After the enormous temperatures of the Hadean period, the early precambrian may have been cooler, requiring prebiotic chemistry to occur below a layer of ice, perhaps heated by volcanic activity such as that found in geothermal vents. A layer of ice several hundreds of kilometres thick may have formed over the entire surface of the early Earth, providing protection from UV radiation and some global warming - conditions such as these may exist on the Jovian moon Europa. 

Figure 8.15 Geothermal vent chemical environment. (Reproduced by permission of Anna-Louise Reysenback and Elsevier Science)...

The salt- and Cu2+-catalysed condensation of peptides provides a very simple polymerisation reaction with remarkable efficiency at 80°C. The proposed mechanism is shown in Figure 8.17 for the dimerisation of glycine. The presence of Cu2+ is important in this process and is unlikely to be present in the geothermal vent environment but it does require only small quantities of O2 to oxidise copper. A better condensation reaction would be autocatalytic and provide a template for future generations - in short, a genetic code. 

Other habitats Surface metabolism and geothermal vents as habitats with selected reaction networks... 

The hydrogen evolution reaction responsible for driving the redox chemistry in geothermal vents is ... 

Globally, volcanoes release about 17 150 metric tons (t) of arsenic per year into the atmosphere (It equals 1000 kg (Matschullat, 2000), 300). Other significant natural sources of gaseous arsenic emissions include geothermal vents, wind erosion of soils and sediments, forest and coal seam fires, and sea spray ((Cullen and Reimer, 1989), 740 (Nriagu, 1989) Chapter 3). Under reducing conditions in soils, fungi and... 

Geothermal vent— An opening in the sea floor occurring between crustal plates. FHot hydrogen sulfide bubbles up through these and supports unusual forms of life. 

There are locations where hydrogen sulfide concentrations are naturally high (e.g., some geothermal vents, bogs of swamps with local area of decaying matter). In these areas, animal and plant life appear to be able to adapt. 

A sulfurous lake in New Zealand lake that is charged by an active underground geothermal vent reportedly averages hydrogen sulfide concentrations ranging from 5 to 3900 ppb. Studies do not report visible effects on local plant and bird populations. 

Natural sources. The Earth s natural volcanic activity can generate sources of carbon dioxide, such as geothermal vents and natural wells. Depending on the location, carbon dioxide concentrations of over 90% can be foimd in imdergroimd wells [93]. 

The Stretford process was jointly developed in the l9S0s in the UK by the North Western Gas Board (now the British Gas Corporation) and the Clayton AnilitK (Company, Ltd. It was originally conceived to replace the iron oxide boxes used for the removal of hytfaogen sulfide from coke-oven gas. However, the process proved to be equally suitable for desulfurization of a variety of other gas streams, such as refinery gas, geothermal vent gas, natural gas, and... 

Drug discovery Extremophiles Geothermal vents Multidrug resistance Peptide antibiotics Secondary metabolites Soda lakes Thermal springs Thermophiles... 

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