典型富铊风化壳中铊同位素分馏研究

表生环境中铊迁移富集所导致的铊污染和环境危害已引起广泛关注,但迄今针对地质源铊的表生迁移富集规律和铊同位素分馏特征仍缺乏清晰认识，尤其缺少原位和精细过程刻画的相关研究。本申请项目以黔西南滥木厂铊矿化区典型富铊风化壳为研究对象，深入研究该风化壳中铊同位素组成变化特征，基于连续化学提取和EXAFS技术，从分子水平上揭示富铊岩石表生风化过程中铊赋存形态转化与铊同位素变化的耦合关系，查明影响风化壳中铊形态组成变化与铊同位素分馏的关键控制因素，揭示风化壳中铊表生迁移富集和铊同位素分馏机制，探讨铊同位素的表生过程环境示踪意义。项目研究成果，有望在国际上率先揭示陆地风化壳中铊同位素分馏特征，为理解和构筑地质源铊的表生迁移富集的地球化学过程机制提供强有力的证据，为地质源铊的判别提供重要指示线索，丰富和深化对铊的表生地球化学循环和同位素分馏规律的认识，充实和发展铊稳定同位素体系，具有较强的理论研究价值。

Thallium (Tl) pollution and associated environmental risks, are causing significant societal concern, because of its mobility and enrichment in surface environments. To date, however, little is known on the mobility, enrichment and isotopic fractionation of geogenic Tl in the surface environment, particularly during the in-situ rock weathering processes. The objective of this project is, for the first time, to gain new insight into Tl isotope fractionation in Tl-rich weathering crust. In combination of sequential extractions, XAFS observation and isotope analysis, this study aims to characterize the distribution, geochemical speciations and isotope fractionation of Tl in the rock weathering process from a representative Tl-rich weathering crust from Lanmuchang area, southwestern Guizhou Province, and to reveal, at molecular level, the linkage between Tl in various geochemical fractions and Tl isotope fractionation. We hope to illustrate the role of geochemical factors in Tl species variation and isotopic fractionation, to gain understanding for mechanism of mobility, enrichment and isotope fractionation of Tl during in-situ Tl-rich rock weathering processes. This will further clarify the significance of Tl isotope tracing in surface environments and will provide a first insight into the Tl isotope fractionation in-situ weathering curst. This insight is crucial to better understanding the geochemical mobility and enrichment of geogenic Tl in surface environments, and for enriching the knowledge about the biogeochemistry and isotopic geochemistry of Tl in surface environments in general.