Effects of pressure on aqueous chemical equilibria at subzero temperatures with applications to Europa

Modeling aluminum–silicon chemistries and application to Australian acidic playa lakes as analogues for Mars

“…FREZCHEM is an equilibrium chemical thermodynamic model parameterized for concentrated electrolyte solutions (to ionic strengths >20 m) using the Pitzer approach (Pitzer, 1991(Pitzer, , 1995 for the temperature range from <À70 to 25°C and the total pressure range from 1 to 1000 bars (Marion and Farren, 1999;Marion, 2001Marion, , 2002Marion et al, 2003Marion et al, , 2005Marion et al, , 2006Marion et al, , 2008bMarion and Kargel, 2008). The previous version of the model was parameterized for the Na-K-Mg-Ca-Fe(II)Fe(III)-H-Cl-Br-SO 4 -NO 3 -OH-HCO 3 -CO 3 -CO 2 -O 2 -CH 4 -H 2 O system and included 83 solid phases including ice, 14 chloride minerals, 30 sulfate minerals, 15 carbonate minerals, five solid phase acids, three nitrate minerals, six acid-salts, five iron oxides, two gas hydrates, and two bromide sinks.…”

Coevolution of Life and Earth

“…Water beyond Earth is frozen or vaporized, with the possible exception of Jupiter's moon Europa (Marion et al, 2005). Impact glasses, shocked minerals, clays, evaporites, carbonates, oxides, and a variety of high-temperature minerals also are found beyond Earth (Squyres et al, 2004).…”

“…On a cosmic scale of temperatures from À270 C (2.76 K) in deep space to about 6000 C for the surface of the sun, the 0-100 C range of liquid water is a narrow range not currently found on any neighboring planetary bodies, though perhaps present within Europa (Marion et al, 2005), and on Mars in the distant geologic past, some 2.5-3.5 Ga (Carr, 1981). It did not last on Mars, but on Earth, there is a continuous record of water-lain sedimentary rocks and precipitates from 3.5 Ga to the present (Allwood et al, 2006).…”

Absolute Salinity, ''Density Salinity'' and the Reference-Composition Salinity Scale: present and future use in the seawater standard TEOS-10

“…This difference is at least a factor of ten smaller than the smallest density differences that can be routinely detected using a densimeter and is certainly negligible for the present purpose. Uncertainties associated with the formulation of FREZCHEM (see, e.g., Marion et al, 2005) may significantly alter the details of Fig. 1, but they would not alter the main result that the errors associated with using the TEOS-10 Gibbs function, with S dens A as the salinity argument, to estimate density changes over the Neptunian range of temperature and pressure changes are negligible.…”