中文摘要：

地下水污染的＂原位修复＂是当今国际上净化地下水最具发展前景的新技术,但对铬污染地下水＂原位修复＂尚未有科学有效的评价方法。定量评价地下水中Cr（Ⅵ）的被还原程度成为保护与修复铬污染地下水的关键问题。通过室内Cr（Ⅵ）的还原实验,分析Cr（Ⅵ）在还原过程中铬稳定同位素变化规律,研究其分馏机理,探索利用铬同位素定量评价地下水中Cr（Ⅵ）还原程度的可行性。研究结果表明：Cr（Ⅵ）在被还原成Cr（Ⅲ）过程中,发生明显的同位素分馏,即反应物中53Cr逐渐富集,同时生成物中52Cr逐渐富集;分馏过程可用瑞利分馏模型描述,分馏系数α为常数0.99842。表明δ53Cr能够定量评价水体中Cr（Ⅵ）的还原程度,为评价地下水铬污染修复提供了新途径。

英文摘要：

＂In-situ remediation＂of contaminated groundwater is a most prosprective technology in the world today,but there is not a scientific and effective method to estimate the technology of＂In-situ remediation＂of Cr-contaminated groundwater.Quantitative evaluation of Cr（Ⅵ） reducibility becomes a key problem of protection and restoration for groundwater pollution by chromium.Typical experiments of Cr（Ⅵ） reduction were conducted to analyze the changing disciplinarian of Cr（Ⅵ） stable isotopes during the reduction of Cr（Ⅵ） to Cr（Ⅲ） and probe into the feasibility of the method using δ53 Cr to quantify Cr（Ⅵ） reduction.Experiments indicate that the reduction of Cr（Ⅵ） to Cr（Ⅲ） in aqueous solutions is accompanied by a significant Cr isotope fractionation,with an enrichment of the heavier isotopes in the residual reactants and lighter isotopes in the reducted products.The process of reduction can be modeled with the Rayleigh Fractionation.Fractionation factor α is a constant of 0.99842.The value of δ53Cr can be used to quantify Cr（Ⅵ） reduction,which provides a new tool for quantifing the extent of chromate natural attenuation and estimating the rate of chromium attenuation.