中文摘要：

氯有两个稳定同位素^35Cl和^37Cl，在自然界中的丰度分别为24．23％和75．77％。自然界中氯同位素的组成变化很小，氯同位素组成的表示方法一般用δ^37Cl值表示：

英文摘要：

Chlorine has two stable isotopes, ^35Cl and ^37Cl, with their abundance being 75.53 % and 24.47 % respectively. Their large relative mass difference suggests that these isotopes should be fractionated during the reactions between aqueous chloride solutions and solid phases in which Cl is at least partly bonded. Large fractionation of Cl isotopes occurs in nature with δ^37Cl variation about 15‰. Chloride isotope composition in modem oceanic water is uniform, so seawater has been suggested as the chlorine isotope standard, SMOC. The river water shows a wide δ^ 37Cl variation of ＋ 0.74‰ - ＋ 2.85%0, the groundwater displays a δ^37Cl variation of - 0.5‰- ＋ 0.69%0, and 3 37Cl of salt lake fluids vary from - 2.06‰ to ＋ 1.0‰. The mid-ocean ridge basahs（MORB） have a large 3 37（71 variation of ＋ 3.2‰- ＋ 7.2‰, whereas the granites show very small δ^37Cl variations of - 0.3‰- ＋ 0.11‰. The carbonatites have δ^37Cl ratios between - 0.8‰ and ＋ 0.1‰, whereas the halites have δ^37Cl values of - 0.6‰ - ＋ 1.2‰. Now,the large δ^37Cl variations in rlature have made Cl isotope composition a very sensitive geochemical tracer, which can be used mainly in such fields as atmospheric aerosol, mid-ocean ridge basalt, crust-mantle evolution, hydrothermal mineralization and origin and evolution of brines.