Inorganic species in geologic fluids: Correlations among standard molal thermodynamic properties of aqueous ions and hydroxide complexes

Thermophilic and hyperthermophilic Archaea and Bacteria have been isolated from marine hydrothermal systems, heated sediments, continental solfataras, hot springs, water heaters, and industrial waste They catalyze a tremendous array of widely varying metabolic processes As determined in the laboratory, electron donors in thermophilic and hyperthermophilic microbial redox reactions include H2, Fe(2+), H2S, S, S2O3(2-), S4O6(2-), sulfide minerals, CH4, various mono-, di-, and hydroxy-carboxylic acids, alcohols, amino acids, and complex organic substrates; electron acceptors include O2, Fe(3+), CO2, CO, NO3(-), NO2(-), NO, N2O, SO4(2-), SO3(2-), S2O3(2-), and S Although many assimilatory and dissimilatory metabolic reactions have been identified for these groups of microorganisms, little attention has been paid to the energetics of these reactions In this review, standard molal Gibbs free energies (DeltaGr(0)) as a function of temperature to 200 degrees C are tabulated for 370 organic and inorganic redox, disproportionation, dissociation, hydrolysis, and solubility reactions directly or indirectly involved in microbial metabolism To calculate values of DeltaGr(0) for these and countless other reactions, the apparent standard molal Gibbs free energies of formation (DeltaG(0)) at temperatures to 200 degrees C are given for 307 solids, liquids, gases, and aqueous solutes It is shown that values of DeltaGr(0) for many microbially mediated reactions are highly temperature dependent, and that adopting values determined at 25 degrees C for systems at elevated temperatures introduces significant and unnecessary errors The metabolic processes considered here involve compounds that belong to the following chemical systems: H-O, H-O-N, H-O-S, H-O-N-S, H-O-C(inorganic), H-O-C, H-O-N-C, H-O-S-C, H-O-N-S-C(amino acids), H-O-S-C-metals/minerals, and H-O-P For four metabolic reactions of particular interest in thermophily and hyperthermophily (knallgas reaction, anaerobic sulfur and nitrate reduction, and autotrophic methanogenesis), values of the overall Gibbs free energy (DeltaGr) as a function of temperature are calculated for a wide range of chemical compositions likely to be present in near-surface and deep hydrothermal and geothermal systems

http://rcn.montana.edu/Resources/LRES555/Manuscripts/energetics.pdf

Energetics of overall metabolic reactions of thermophilic and hyperthermophilic Archaea and Bacteria

The rainbow vent fluids (36°14′N, MAR): the influence of ultramafic rocks and phase separation on trace metal content in Mid-Atlantic Ridge hydrothermal fluids

The lanthanide tetrad effect and its correlation with k/rb, eu/eu*, sr/eu,y/ho, and zr/hf of evolving peraluminous granite suites

Comparing yttrium and rare earths in hydrothermal fluids from the Mid-Atlantic Ridge: implications for Y and REE behaviour during near-vent mixing and for the Y/Ho ratio of Proterozoic seawater

Rare earth elements in hydrothermal systems: Estimates of standard partial molal thermodynamic properties of aqueous complexes of the rare earth elements at high pressures and temperatures

Twenty about 100-mg random fragments of the Bruderheim chondrite were analyzed by INAA to determine extents of heterogeneity and to check earlier results that gave anomalous LREE concentrations. Considerable compositional heterogeneity was observed in both concentrations (maximum/minimum of 1.7 for Ir, 1.8 for Na, 6.8 for La, 7.4 for Co) and concentration ratios (greater than 3 x for Ni/Co and La/Eu). Compositions could be modeled quantitatively in terms of end-member components of constant composition representing the minerals olivine + orthopyroxene, clinopyroxene, plagioclase, kamacite, taenite, troilite, chromite, and phosphate. The model yields the proportions of minerals in each sample as well as the meteorite as a whole; accurate determination of the end members depends on high intrasample precision for many elements. No evidence of compositional heterogeneity of end members for trace elements was found. It is shown that these analyses, which used only about 2 grams of the meteorite, are equivalent in accuracy to a single sample of several tens of grams, and that knowledge of the extent of heterogeneity is essential to knowing the quality of sampling as well as for comparing results from one analysis with another and of one meteorite with another.

Johnson R. Haas

Papers

Rare earth elements in hydrothermal systems: Estimates of standard partial molal thermodynamic properties of aqueous complexes of the rare earth elements at high pressures and temperatures

Compositional variations among whole-rock fragments of the L6 chondrite Bruderheim