Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/727
AuthorsAmend, J. P.* 
Rogers, K. L.* 
Shock, E. L.* 
Gurrieri, S.* 
Inguaggiato, S.* 
TitleEnergetics of chemolithoautotrophy in the hydrothermal system of Vulcano Island, Southern Italy
Issue Date2003
Series/Report no.1(2003)
URIhttp://hdl.handle.net/2122/727
Keywordshydrothermal system
Vulcano Island
Subject Classification03. Hydrosphere::03.04. Chemical and biological::03.04.04. Ecosystems 
03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems 
AbstractThe hydrothermal system at Vulcano, Aeolian Islands (Italy), is home to a wide variety of thermophilic,chemolithoautotrophic archaea and bacteria. As observed in laboratory growth studies, these organisms may use an array of terminal electron acceptors (TEAs), including O 2, NO-3,Fe(III),elemental sulphur and CO2; electron donors include H2,Fe2+,H2S and CH4. Concentrations of inorganic aqueous species and gases were measured in 10 hydrothermal fluids from seeps, wells and vents on Vulcano. These data were combined with standard Gibbs free energies ( ) to calculate overall Gibbs free energies (DGr) of 90 redox reactions that involve 16 inorganic N-, S-, C-, Fe-, H- and O-bearing compounds. It is shown that oxidation reactions with O2 as the TEA release significantly more energy (normalized per electron transferred) than most anaerobic oxidation reactions, but the energy yield is comparable or even higher for several reactions in which, or Fe(III) serves as the TEA. For example, the oxidation of CH4 to CO2 coupled to the reduction of Fe(III) in magnetite to Fe2+ releases between 94 and 123 kJ/mol e– , depending on the site. By comparison, the aerobic oxidation of H2 or reduced inorganic N-, S-, C- and Fe-bearing compounds generally yields between 70 and 100 kJ/mol e–. It is further shown that the energy yield from the reduction of elemental sulphur to H2 S is relatively low (8–19 kJ/mol e–) despite being a very common metabolism among thermophiles. In addition,for many of the 90 reactions evaluated at each of the 10 sites, values of DGr tend to cluster with differences < 20 kJ/mol e–. However, large differences in DGr up to ~ 60 kJ/mol e–) are observed in Fe redox reactions, due largely to considerable variations in Fe 2+, H + and H2 concentrations. In fact, at the sites investigated, most variations in DGr arise from differences in composition and not in temperature.
Appears in Collections:Papers Published / Papers in press

Files in This Item:
File Description SizeFormat 
Amend et al., Geobiology 2003.pdfMain article634.42 kBAdobe PDFView/Open
Redirect Blackwell.htmlRedirect-Blackwell543 BHTMLView/Open
Show full item record

Page view(s)

106
Last Week
0
Last month
0
checked on Jul 26, 2017

Download(s)

59
checked on Jul 26, 2017

Google ScholarTM

Check