U同位素分馏行为及其在环境地球科学中的应用研究进展  

Uranium isotope fractionation and application of uranium isotopes in environmental geosciences—a review

作　　者：李茜 朱光有[1] 李婷婷[1] 陈志勇[1] 艾依飞 张岩 田连杰 LI Xi;ZHU Guangyou;LI Tingting;CHEN Zhiyong;AI Yifei;ZHANG Yan;TIAN Lianjie(PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China)

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《地学前缘》2024年第2期447-471,共25页Earth Science Frontiers

基　　金：中国石油天然气股份有限公司科学研究与技术开发项目“海相碳酸盐岩成藏理论与勘探技术研究(2021DJ05)”。

摘　　要：近年来,研究铀(U)及其同位素有关的地球化学指标在地球环境科学领域发挥着越来越重要的作用。为加快我国U同位素发展和应用,本文系统回顾了近20年来U及其同位素的地球化学行为、U同位素分析测试技术、U循环与地表U同位素组成、U同位素分馏机理以及U同位素在环境科学领域的应用进展与技术壁垒。综述表明:U作为氧化还原敏感元素,在自然和人为活动中,U同位素存在显著分馏现象。U同位素已初步成功应用于示踪现代陆地表生环境系统中U的分布、迁移和扩散行为,重建地质历史时期环境与生命协同演化过程等地球环境科学领域。但总体而言,国内外U同位素研究工作仍处于起步阶段,多数局限于定性分析,在应用中也存在一些问题亟待解决,例如:特殊价态的U同位素仍无法测量,这制约了进一步对氧化还原过程中U同位素分馏机理的认识;地下水U污染处理手段缺失,表生沉积物的U同位素测试数据缺乏系统性和区域性,大气定量源计算解析模型还未完全建立;碳酸盐岩成岩过程中的U同位分馏机理尚不清楚,其分馏校正因子难以确定;黑色页岩包含海水和沉积物混杂的化学信号,难以准确扣除局部无效分馏信号;对非重大地质事件时期的关注较少导致无法恢复地球完整的氧化还原历史;U同位素高温地球化学分馏机理与应用基本处于空白等。未来,进一步改善U同位素测试技术,提高仪器检测分析精度,进行更系统的U同位素测试,建立各类型U同位素数据库,深化U同位素分馏机理认识,筑牢U同位素应用基石,尝试U同位素在更多领域的探索,以及将U同位素与其他氧化还原系统相关的示踪剂联合使用以提高示踪的准确性和可靠性,是U同位素研究的主要方向。本文对进一步推动我国U同位素在环境地球科学领域中的应用具有深远意义。In recent years,uranium(U)isotopes as geochemical indicators play an increasingly important role in environmental studies.To accelerate the development and application of U isotopes in China,this paper performs a systematic review on U geochemistry,U isotope analysis and testing techniques,U cycling and isotopic composition of surface U,mechanism of U isotope fractionation,and research progress on and technical barriers to the application of U isotopes in environmental geosciences in the past two decades.Uranium as a redox-sensitive element,significant U isotope fractionation has been observed in natural and anthropogenic environments.Uranium isotopes have been successfully applied to trace U distribution,transport,and diffusion behavior in modern terrestrial epigenetic systems and to reconstruct the history of synergistic coevolution between the environment and living organisms over geological and historical periods.However,in general,U isotope research both at home and abroad is still in its infancy,mostly limited to qualitative analysis,and some application issues need to be solved.For example,U isotopes with certain valency are still not measurable,hindering a further understanding of the mechanism of U isotope fractionation during redox processes;other lackings include the means to deal with U contamination in groundwater;systematic,regional U isotope test data on epigenetic sediments;and analytical models for quantitative atmospheric source calculations.Among other issues,the mechanism of U isotope fractionation during carbonate rock formation is still unclear and the fractionation correction factor is difficult to determine.In paleoreconstruction,the use of U isotopes of black shale is problematic as accurate isotope data are difficult to obtain due to local signal interference,and the lack of isotope data on non-major geological events makes it impossible to recover the complete redox history of the Earth.Research on the geochemical mechanism of U isotope fractionation at high temperature and related appl

关 键 词：U同位素 U循环 分馏机理 环境科学 地球科学 U示踪 

分 类 号：P597.1[天文地球—地球化学] X14[天文地球—地质学]