湖水同位素平衡研究中分馏系数和富集系数计算形式的组合选择

Choice of the Combined Calculating Forms of Equilibrium Fractionation Factor and Equilibrium Enrichment Factor in the Research on Lake Water Isotopic Equilibrium

湖泊自生碳酸盐δ18O(δ18Oc)是研究湖泊水体同位素平衡和气候变化的重要环境同位素指标。由于δ18Oc与湖水δ18O(δ18Ow)密切相关,前人建立了δ18Ow的计算公式,这方面的研究对于δ18Oc环境意义的正确判读十分重要。δ18Ow计算公式中的平衡分馏系数α和平衡富集系数ε各有几种计算形式,当两个参数同时出现时,其计算形式须正确组合:当α>1时,ε=α-1或ε=1-1/α;当α<1时,ε=1-α或ε=1/α-1。其中"α>1,ε=α-1"组合最常用。

δ^(18)O of lacustrine authigenic carbonates,i.e.δ^(18)O_c is an important environmental isotopic indicator for the study of lake water isotopic balance and of climatic evolution.Because δ^(18)O_c is highly correlated with the δ^(18)O of lake water,i.e.δ^(18)O_w,the calculating formulae of δ^(18)O_w have been established which redound to the correct estimation of the environmental significance of δ^(18)O_c.In the applications of the calculating formulae of δ^(18)O_w,the two parameters,i.e.equilibrium fractionation factor α and equilibrium enrichment factor ε both have several different calculating forms which should be combined correctly.when α is defined as α>1,ε is therefore equal to α-1 or 1-1/α;while when α is defined as α<1,ε is therefore equal to 1-α or 1/α-1.Among the different combined calculating forms,the form'α>1,ε=α-1'is mostly cited.