Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

Development of an experimental data base and theories for prediction of thermodynamic properties of aqueous electrolytes and nonelectrolytes of geochemical significance at supercritical temperatures and pressures

The following new synonyms are proposed for the genera and species of flea beetles predominantly from the Oriental Region: Pseudocrypta Medvedev, 1996 and SebaethiellaMedvedev, 1993 5 Acrocrypta Baly, 1862; Bhutajana Scherer, 1979 5 Aphthona Chevrolat, 1836; Burmaltica Scherer, 1969 5 Aphthonaltica Heikertinger, 1924; Aphthonomorpha Chen, 1934 and Manobidia Chen, 1934 5 Bikasha Maulik, 1931; Garuda Scherer, 1969 5 Chalaenosoma Jacoby,1893; Priostomus Jacoby, 1884 5 Chaloenus Westwood, 1862; Throscoryssa Maulik,1928 5 Clitea Baly, 1877; Eucyclomela Chen, 1934 and Schenklingia Csiki & Heikertinger, 1940 5 Halticorcus Lea, 1917; Luperaria Medvedev, 1993 5 Laboissierella Chen, 1933; Lipraria Medvedev, 1990 5 Lipromela Chen, 1933; Asiorella Medvedev, 1990 5 Liprus Motschulsky, 1860; Docemasia Jacoby, 1899 5 Luperomorpha Weise, 1887; Ceylonaltica Doeberl, 1996 and Mesopa Jacoby, 1903 5 Micraphthona Jacoby, 1900; Martensomela Medvedev, 1984 and Nepalicrepis Scherer, 1969 5 Microcrepis Chen, 1933; Nepalicrepis darjeelingensis Scherer, 1969 5 Microcrepis politus Chen, 1933; Epithrella Medvedev, 1993 and Livoliella Medvedev, 1997 5 Orthaltica Crotch, 1873; Chabriosoma Chen, 1934 5 Phygasoma Jacoby, 1898; Letzuana Chen, 1934 5 Phyllotreta Chevrolat, 1836; Kimotoa Gruev, 1985 5 Sphaeroderma Stephens, 1831; Amydus Chen, 1935, Monodaltica Bechyne, 1955, Trachyaphthona Heikertinger, 1924, and Typhodes Samuelson, 1984 5 Trachytetra Sharp, 1886. Habitus and/or other morphological structures are illustrated for each genus under consideration

High pH microbial ecosystems in a newly discovered, ephemeral, serpentinizing fluid seep at Yanartaş (Chimera), Turkey

Gas seeps emanating from Yanartaş (Chimera), Turkey, have been documented for thousands of years. Active serpentinization produces hydrogen and a range of carbon gases that may provide fuel for life. Here we report a newly discovered, ephemeral fluid seep emanating from a small gas vent at Yanartaş. Fluids and biofilms were sampled at the source and points downstream. We describe site conditions, and provide microbiological data in the form of enrichment cultures, Scanning electron microscopy (SEM), carbon and nitrogen isotopic composition of solids, and PCR screens of nitrogen cycle genes. Source fluids are pH 11.95, with a Ca:Mg of ~200, and sediments under the ignited gas seep measure 60°C. Collectively, these data suggest the fluid is the product of active serpentinization at depth. Source sediments are primarily calcite and alteration products (chlorite and montmorillonite). Downstream, biofilms are mixed with montmorillonite. SEM shows biofilms distributed homogeneously with carbonates. Organic carbon accounts for 60% of the total carbon at the source, decreasing downstream to <15% as inorganic carbon precipitates. δ13C ratios of the organic carbon fraction of solids are depleted (−25 to −28‰) relative to the carbonates (−11 to −20‰). We conclude that heterotrophic processes are dominant throughout the surface ecosystem, and carbon fixation may be key down channel. δ15N ratios ~3‰, and absence of nifH in extracted DNA suggest that nitrogen fixation is not occurring in sediments. However, the presence of narG and nirS at most locations and in enrichments indicates genomic potential for nitrate and nitrite reduction. This small seep with shallow run-off is likely ephemeral, but abundant preserved microterracettes in the outflow and the surrounding area suggest it has been present for some time. This site and others like it present an opportunity for investigations of preserved deep biosphere signatures, and subsurface-surface interactions

Development of an experimental data base and theories for prediction of thermodynamic properties of aqueous electrolytes and nonelectrolytes of geochemical significance at supercritical temperatures and pressures

This project is divided into method experimental measurements, theoretical development, and geochemical applications. We have completed experimental volumetric measurements on aqueous solutions of CO{sub 2} H{sub 2}S, CH{sub 4}, NH{sub 3} and B(OH){sub 3} at 25 to 432{degree}C and 280 and 350 bar. A vibrating tube densitometer that allows density measurements near bubble point and also measures the bubble pressure was developed and used to measure densities and bubble pressures of aqueous Co{sub 2}. Heat capacity measurements should be completed by the end of the grant period. Simulations of models for methane in water at temperatures to 1000{degrees}C are in progress. In order to facilitate these free energy calculations the possible errors associated with the calculations have been explored in two papers (Wood, 1991; Wood et al., 1991) and methods of controlling and estimating these errors have been developed. Applications of the new data to geochemical processes is now possible. Efforts have focussed on extracting equilibrium constants for carbonic acid dissociation at supercritical condition from published experiments on mineral equilibria in H{sub 2}0-CO{sub 2} fluids (Boehlke and Shock, 1990; and in prep.). As a result, estimates of pKa for carbonic acid are now available at temperatures from 300 to 750{degrees}C and pressures from 1 to 7 kilobars. They will be combined with {bar V}{sup {degree}} and {bar C}p{sup {degree}} data for CO{sup 2}(aq) to improve geochemical calculations