空气中H₂¹⁶O/H₂¹⁷O和H₂¹⁶O/H₂¹⁸O的扩散分馏及其对同位素水文学的意义。

Diffusivity fractionations of H2(16)O/H2(17)O and H2(16)O/H2(18)O in air and their implications for isotope hydrology.

作者信息

Barkan Eugeni, Luz Boaz

机构信息

The Institute of Earth Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel.

出版信息

Rapid Commun Mass Spectrom. 2007;21(18):2999-3005. doi: 10.1002/rcm.3180.

DOI:10.1002/rcm.3180

PMID:17705344

Abstract

We have determined the isotope effects of (17)O and (18)O substitution of (16)O in H(2)O on molecular diffusivities of water vapor in air by the use of evaporation experiments. The derived diffusion fractionation coefficients (17)alpha(diff) and (18)alpha(diff) are 1.0146 +/- 0.0002 and 1.0283 +/- 0.0003, respectively. We also determined, for the first time, the ratio ln((17)alpha(diff))/ln((18)alpha(diff)) as 0.5185 +/- 0.0002. This ratio, which is in excellent agreement with the theoretical value of 0.5184, is significantly smaller than the ratio in vapor-liquid equilibrium (0.529). We show how this new experimental information gives rise to (17)O excess in meteoric water, and how it can be applied in isotope hydrology.

摘要

我们通过蒸发实验确定了H₂O中¹⁶O被¹⁷O和¹⁸O取代对空气中水蒸气分子扩散率的同位素效应。推导得到的扩散分馏系数¹⁷α(diff)和¹⁸α(diff)分别为1.0146±0.0002和1.0283±0.0003。我们还首次确定了ln(¹⁷α(diff))/ln(¹⁸α(diff))的比值为0.5185±0.0002。该比值与理论值0.5184高度吻合，且显著小于气液平衡中的比值(0.529)。我们展示了这一新的实验信息如何导致大气降水出现¹⁷O过剩，以及它如何应用于同位素水文学。