河流Mg同位素示踪流域化学风化研究进展  

Review on Chemical Weathering Within a Drainage Basin Traced by Mg Isotopes

作　　者：王若雯 高全洲[1,2,3] WANG Ruo-wen;GAO Quan-zhou(School of Geography and Planning,Sun Yat-sen University,Guangzhou 510006,Guangdong,China;Guangdong Key Laboratory for Urbanization and Geo-simulation,Sun Yat-sen University,Guangzhou 510006,Guangdong,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519080,Guangdong,China)

机构地区：[1]中山大学地理科学与规划学院,广东广州510006 [2]中山大学广东省城市化与地理环境空间模拟重点实验室,广东广州510006 [3]南方海洋科学与工程广东省实验室(珠海),广东珠海519080

出　　处：《地球科学与环境学报》2023年第4期953-965,共13页Journal of Earth Sciences and Environment

基　　金：国家自然科学基金项目(41871014,U1901209)。

摘　　要：河流Mg同位素体系示踪大陆化学风化过程的潜力近年来受到重视。通过总结Mg同位素在流域地表过程中的地球化学行为,发现河流Mg主要来源于矿物化学风化、大气降水、地下水以及植物残骸。全球主要径流Mg同位素组成呈现较大的变异性,仅用流域Mg储库的保守混合难以完全解释,因为大陆化学风化过程中基岩的差异风化和Mg同位素分馏是河水Mg同位素组成的重要影响因素。影响河水Mg同位素组成的主要分馏过程包括原生矿物分解、次生矿物形成、可交换态的吸附-解吸以及植物吸收和残体释放等过程。目前对河流Mg同位素体系的一级控制过程仍了解不多。在全球尺度下,大型河流Mg同位素组成与碳酸盐矿物的化学风化强度成显著相关关系。此外,Mg-Sr、Mg-Li、Mg-Ca以及Mg-O等多同位素体系也为地表环境演变研究提供了有力的示踪工具。今后应加强对流域关键过程Mg同位素分馏因子、特殊化学风化类型、多同位素耦合联用以及Mg同位素定量示踪的探讨,推动河流Mg同位素在示踪流域化学风化研究中的应用。The potential of river Mg isotope systems to trace continental chemical weathering processes has been emphasized in recent years.The geochemical behavior of Mg isotopes in the surface process of the watershed was summarized.The results show that river Mg is mainly derived from mineral chemical weathering,atmospheric precipitation,groundwater and plant debris.Mg isotopic composition of the world s major runoff shows great variability,which is difficult to fully explain by the conservative mixing of Mg reservoirs in the basin alone,because the differential weathering of bedrock and Mg isotope fractionation during continental chemical weathering is important influencing factor of Mg isotopic composition in river water.The main fractionation processes affecting Mg isotopic composition in river water include primary mineral decomposition,secondary mineral formation,adsorption-desorption of exchangeable states,plant uptake and debris release.At present,the primary control process of river Mg isotope system is still not well understood.On a global scale,Mg isotopic composition of large rivers correlates well with the chemical weathering strength of carbonate minerals.In addition,multi-isotopic systems such as Mg-Sr,Mg-Li,Mg-Ca and Mg-O also provide powerful tracing tools for the study of surface environment evolution.In the future,the discussion on Mg isotope fractionation factors,special chemical weathering types,multi-isotope coupling combination and quantitative tracing of Mg isotopes in key processes in river basins should be strengthened,and the application of river Mg isotopes in chemical weathering in river basins should be promoted.

关 键 词：MG同位素 非传统稳定同位素 分馏 化学风化 碳循环 地球化学 示踪应用 河流 

分 类 号：P595[天文地球—地球化学]