PHASE EQUILIBRIUM AND FRACTIONATION OF NOBLE GASES

PHASE EQUILIBRIUM AND FRACTIONATION OF NOBLE GASES Liquid-gas phase partitioning of noble gases 

Noble gas partitioning and solubility fractionation between equilibrated subsurface phases was initially studied by Goryunov and Kozlov (1940) and further studied (Zartman et al. 1961 Bosch and Mazor 1988 Zaikowski and Spangler 1990 Ballentine et al. 1991 Ballentine et al. 1996 Hiyagon and Kennedy 1992 Pinti and Marty 1995 Torgersen and Kennedy 1999 Battani et al. 2000). Recent reviews are by O Nions and Ballentine (1993), Ballentine and O Nions (1994) and Pinti and Marty (2000). 

Under equilibrium conditions, the distribution of noble gases between gas and liquid phases is given by Henry s Law (Eqn. 1). Following Goryunov and Kozlov (1940) and Zartman et al. (1961) and assuming ideal behavior in the gas phase, another form of this equation is derived when the concentration i in the gas phase Cg is related to the concentration in the liquid phase phase Ci by 

Henry s constant in this form, Kj, is dimensionless. For a fixed volume of gas and liquid, the number of moles in the gas phase [i]g is related to the total number of moles present [i]x and the liquid to gas volume ratio, ViWg, by 

It can be seen that Henry s constants can be dimensionless (Ki, Eqn. 12) expressed in units of pressure, (Ki, Eqn. 2) or take the molaltity format, K (Tables 3 and 4). A similar form of Equation (13) for Ki or K can be simply derived taking due account of units. For example we consider Henry s constant, Ki, expressed in units of atm and water as the liquid phase. In this case the mole fraction, Xi, can be related to the concentrations in terms of the water density, Ph20 (g/cm ) and the water volume, Vh20 (cm ) where 

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