Pressure effects on the reduced partition function ratio for hydrogen isotopes in water

D/H fractionation in the H2–H2O system at supercritical water conditions: Compositional and hydrogen bonding effects

“…Walrafen et al (1996) The role of temperature in promoting differences in the density and polarity of hydrogen-bonded OHO and ODO molecules might contribute to development of different partial molar volume between D-and H-bearing species in H 2 O + D 2 O systems, and, thus, cause isotopic fractionation effects similar to the pressure effects documented for the D/ H fractionation between H 2 O and hydroxide mineral phases (e.g. brucite) (Horita et al, 1999(Horita et al, , 2002(Horita et al, , 2010Polyakov et al, 2006). These latter fractionations have been attributed to molar volume isotope effects (MVIE) closely associated with the differences of the molar volume of isotope species as a function of pressure and temperature (Jancso et al, 1993;Lacks, 1995;Horita et al, 2002;Polyakov et al, 2006).…”

“…brucite) (Horita et al, 1999(Horita et al, , 2002(Horita et al, , 2010Polyakov et al, 2006). These latter fractionations have been attributed to molar volume isotope effects (MVIE) closely associated with the differences of the molar volume of isotope species as a function of pressure and temperature (Jancso et al, 1993;Lacks, 1995;Horita et al, 2002;Polyakov et al, 2006). For example, theoretical calculations performed by Polyakov et al (2006) showed that for supercritical fluids at elevated pressures the molar volume of deuterated water is greater than V H 2 O , resulting in preferential incorporation of hydrogen over deuterium into water, which in turn contributes to the decrease in the equilibrium constant of the H 2 O-D 2 O-HDO reaction (Eq.…”

Theoretical and Experimental Principles

“…This assumption is generally fulfilled, except for hydrogen. Driesner (1997), Horita et al (1999Horita et al ( , 2002 and Polyakov et al (2006) have shown, however, that for isotope exchange reactions involving water, changes of pressure can influence isotope fractionations. Driesner (1997) calculated hydrogen isotope fractionations between epidote and water and observed at 400°C a change from -90 ‰ at 1 bar to -30 ‰ at 4000 bars.…”

First-principles calculation of H/D isotopic fractionation between hydrous minerals and water

“…While comparing theoretical mineral/liquid water fractionation laws to measurements at P sat ðT Þ, we will consider ln a à and refer to "pressure correction" as the difference between ln a and ln a à . Most estimates of these pressure effects come from theoretical calculations (Polyakov et al, 2006;Reynard and Caracas, 2009;Horita et al, 2002). For brucite, Reynard and Caracas (2009) theoretically predict a positive D ln bðbrucite; P sat ; T Þ which does not exceed 0.06& over the complete temperature domain.…”

“…In general, the contribution of the mineral term in the "pressure correction" is expected to be negligible. For gas water, Polyakov et al (2006) theoretically predict a pressure correction (ÀD ln bðgas; P sat ; T Þ) between 0& and À0.5& below 130°C, reaching À1.3& at 300°C and then decreasing in absolute value towards T c (c.f. Fig.5 of Polyakov et al, 2006).…”