Fractionation of hydrogen isotopes caused by the difference of the crystal structure of hydrous minerals.

介绍了含水矿物结晶水饱和溶液-水蒸气体系中D/H分馏的研究结果。在平衡条件下，实验测定了结晶水合物中的结晶水与过渡金属二氯化物饱和溶液α_&lt；CW-st.Sol&gt；之间的D/H分馏因子。得到了lnα_&lt；C.W.-st.Sol&gt；与1/T^2在10~43℃温度范围内对六水氯化钴结晶水的经验关系式为：10^3LNα_&lt；Cw-st.Sol&gt；=-2.46(10^6/T^2)+17.6。与纯水及其水蒸气之间的D/H分馏因子相比，Inα_&lt；C.W.-st.Sol&gt；的温度依赖性很小。二氯化钴的结晶水比六水合二氯化钴的结晶水对氘的消耗更大。α_&lt；CW-st.Sol&gt；在25℃时，二氯化钴水合物的值与二氯化铜水合物的值相近。结晶水合物中结晶水与饱和水合物之间的D/H分馏系数强烈依赖于结晶水合物的结构，而不是阳离子的化学物种和/或结晶温度。为了确保用电容压力计准确、准确地获得水和D2O的蒸汽压，采用高温玻璃管制作了真空蒸气压测量装置。测定了CoCl26H2O和CoCl26D2O的离解压力以及CoCl2在H2O和D2O饱和溶液中的平衡蒸汽压。结果表明，结晶水合物在H_2O中的离解压力高于在D_2O中的离解压力，与饱和溶液的平衡蒸汽压略有不同。

The purpose of this study was to present results for D/H fractionation in the crystal water-saturated solution-water vapor system of hydrous minerals. The D/H fractionation factors between the crystal water in crystalline hydrates and the saturated solution of transition metal dichloride, α_<CW-st.sol>, were experimentally determined under equilibrium condition. The empirical relationship between lnα_<C.W.-st.sol> and 1/T^2 on the crystal water of cobalt dichloride hexahydrate in the temperature range from 10 to 43℃ was obtained as : 10^3ln α_<CW-st.sol> = -2.46(10^6/T^2) + 17.6. The temperature dependence of In α_<C.W.-st.sol> is very small in comparison with that of the D/H fractionation factor between pure water and its vapor. The crystal water of cobalt dichloride dehydrate exhibits larger depletion of deuterium than that of cobalt dichloride hexahydrate. The value of α_<CW-st.sol> in cobalt dichloride dehydrate shoves similar to that of copper dichloride dehydrate at 25℃. The D/H fractionation factor between the crystal water in crystalline hydrate and saturated solution strongly depends on the structure of crystalline hydrate rather than the chemical species of cation and/or the crystallized temperature.In order to ensure that the vapor pressure of H_2O and D_2O is accurately and precisely obtained using the capacitance manometer, the apparatus of the vapor pressure measurement was made by Pyrex glass tube and was produced a vacuum. The dissociation pressure far CoCl_26H_2O and CoCl_26D_2O and the vapor pressure in equilibrium with the saturated solution of CoCl_2 in H_2O and D_2O were measured. It was found that the dissociation pressure of crystalline hydrate in H_2O is higher than that in D_2O and is slightly different from the vapor pressure in equilibrium with its saturated solution.