地球与环境

文章摘要

表生风化淋滤迁移过程的Cd同位素分馏及其指示意义

Cadmium Isotopic Fractionation during the Supergenic Weathering and Leaching Process and Its Implication

投稿时间：2013-03-06 修订日期：2013-05-18

DOI：

中文关键词: Cd同位素;淋滤实验;重金属污染;同位素示踪

英文关键词: Cd isotope;leaching experiment;heavy metal pollution;isotopic tracing

基金项目:国家自然科学基金项目(40930425,41173029)。

作者	单位	E-mail
张羽旭¹, 周倩¹, 朱传威^1,2, 贺茂勇³, 樊海峰¹, 罗重光¹, 杜胜江^1,2, 温汉捷¹	1. 中国科学院地球化学研究所矿床地球化学国家重点实验室, 贵阳 550002 2. 中国科学院大学, 北京 100049 3. 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室, 西安 710075	wenhanjie@vip.gyig.ac.cn

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中文摘要:

利用Cd同位素来示踪Cd污染源是近年发展起来的一个新的同位素示踪体系,具有极大的优越性。然而,在利用Cd同位素示踪污染源的研究中,表生风化淋滤作用是否会导致同位素分馏,目前还没有研究报导,限制了Cd同位素在示踪污染源方面的应用。通过对Pb-Zn矿山主要固体污染源的表生风化淋滤过程进行模拟实验表明,无论是淋滤实验还是可交换态Cd实验,淋滤液总体上较残留态富集Cd的重同位素,其中尤以硫化矿最为明显,其Cd同位素分馏可达0.50‰(δ^114/110Cd)。此外, Cd的淋滤率与淋滤产生的Cd同位素分馏总体呈负相关关系。因此,我们认为在利用Cd同位素端元模型示踪污染源时,必须充分考虑表生风化淋滤作用可能带来的影响。

英文摘要:

Cd isotopes have been useful proxies to trace the pollution sources, which show apparent advantages in the field study. However, it is not well known whether the supergenic weathering and leaching process could cause Cd isotope fractionation or not, which hampers the applications of Cd isotopes to tracing the pollution sources. Leaching experiments and exchangeable Cd experiments on different typical samples from lead-zinc mines shoned that the leached liquids always favor heavier Cd isotopes than the corresponding residuals. The obvious Cd isotope fractionation between leached liquids and residual could come up to about 0.50‰, which was observed in the sulfide samples. Meanwhile, a negative correlation between the Cd concentrations in leached liquids and the δ^114/110Cd values was found in this study. These results suggested that when Cd isotopes are used to trace the pollution sources, the isotope fractionation from the supergenic weathering process must be taken into consideration.

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