Thermal venting

As explained previously, thermal venting has been established for a temperature variation of 37.8°C/h. The rate of thermal venting is also flash-point and boiling-point dependent (see Table 4.11). 

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To attain the total venting (outbreathing) requirements for a tank, refer to tlie appropriate flash point column and add the outbreathing plus the thermal venting flows. 

Thermal Venting Capacity (cubic feet of free air per hour)... 

F17 Deposition of marine sulfate via thermal vent reactions at midocean ridges 43 ... 

Woese chose the name archaebacteria because these microorganisms grow best under conditions which were probably found on the primeval Earth between 3.5 and 4 billion years ago hot boiling water and thermal vents, highly acidic environment, oxygen-free atmosphere and high salt concentrations. 

Figure 2.3 Metagenomic cloning experiments. Isolation of genomic DNA directly from environments (soil, plants, mixed environments or thermal-vent worms are the examples Illustrated here) can recover DNA fragments which could encode for enzymes. The DNA fragments can be ligated to plasmids or DNA linkers, and then subjected to functional screening (expression cloning) and/or sequence analysis. Amplification by PCR can sometimes be used to yield libraries enriched with clones containing selected sequence motifs relating to families of enzymes...

Metalliferous sediments are a common component of modern ocean-floor sedimentary sequences, recording halos of metal dispersion from seafloor hydro-thermal vent systems (Gurvich, 2006). Sulfidic black shales are also commonly present as intercalations in ancient subaqueous volcanic sequences, where each likely represents a significant hiatus in volcanic activity and deposition. These shale horizons form geophysical anomalies (conductors) that are routinely drilled during exploration for volcanogenic massive sulfide (VMS) base metal deposits. 

Fortin, D. Ferris, F.G. Scott, S.D. (1998) Formation of Fe-silicates and Fe-oxides on bacterial surfaces in samples collected near hydro-thermal vents on the Southern Explorer Ridge in the northeast Pacific Ocean. Am. Min. 83 1399-1408... 

Jannasch, H.W. Wirsen, C.O. (1981) Morphological survey of microbial mats near deep-sea thermal vents. Appl. Environ. Microbiol. 41 528-538... 

Tungsten Rare. Found io enzymes m thermophilic (thermal vent) bacteria. ... 

The common ancestor of life was probably a chemoautotrophic hyperthermophilic anaerobe. This metabolism first theory assumes that life started with catalytic metal sulfide surface/compartments in a hydro thermal-vent setting in the Hadean... 

The general reaction accounts for the fact that in some systems, something other than water supplies the reducing equivalents. For example, bacteria living in deep-sea thermal vents can apparently use hydrogen sulfide (H2S) as a source of reducing equivalents to synthesize glucose from carbon dioxide dissolved in the seawater. 

As the exploration of the biosphere has continued, environments on Earth have been discovered that are quite different from and alien to human-like life. Nevertheless, where an environment has been found to contain a chemical disequilibrium, if liquid water is also present and the temperature does not exceed the upper limit for covalent bonding of core biomolecules, life is present. Active life has been found in deep-ocean thermal vents at temperatures in excess of 112°C. Life has been found in Antarctica where liquid water exists only transiently. It has been found 5 km below Earth s surface in mine shafts, and in the effluents of mining operations at Rio Tinto, Spain, that are as acidic as dilute sulfuric acid. Several of those environments are summarized in Table 3.1. 

Current research is showing the interactions between organic molecules and a wide array of minerals. These include the formation of carboxylic acids in thermal vent chemistry and the formation of reduced chemical species through photochemistry involving semiconducting minerals.8... 

Piezophile An organism adapted to living in high-pressure environments, such as hydro-thermal vents... 

Simplicity of structure and ease of formation makes it reasonable to infer that polyP and PHB were components of early cells, possibly preceding RNA. PolyPs are prebiotic molecules, formed by condensation of phosphates in volcanic condensates and thermal vents at the bottom of the ocean.2,34,146 The synthesis of PHB is more demanding but requires only acetate and a reducing agent (see Figure 2B), both available in the primordial milieu. The conservation of these rudimentary homopoly-... 

Early life forms thriving near thermal vents in waters enriched in heavy metal ions would have had to have been endowed with mechanisms to deal with toxic metal ions and it is conceivable that efflux mechanisms for these metals evolved before or concomitandy with their use as cofactors. In line with such a hypothesis, the CPx-type ATPases encompass a wider spectrum of ion specificities than the non-heavy metal ATPases, now including Cu+, Ag+, Zn +, Cd +, and Pb. It is to be expected that other metal ions will be added to this list. ATPases transporting silver, zinc, cadmium, and lead are involved in bacterial resistance to these toxic metal ions, while copper-transporting ATPases have a role both in copper uptake to meet cellular demands and in copper extrusion when ambient... 

O Grady K. M. (2001) The geochemical controls on hydro-thermal vent fluid chemistry from two areas on the ultrafast spreading southern East Pacific Rise. MSc Thesis, University of New Hampshire, 134pp. 

Michard A., Albarede E., Michard G., Minster J. F., and Charlou J. L. (1983) Rare-earth elements and uranium in high-temperature solutions from East Pacific Rise hydro-thermal vent field (13-degrees-N). Nature 303(5920), 795-797. 

Thermodesulfovibrio yellowstonii Thermal vent water Lactate (20) 17.0... 

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