Roles of natural organic matter in fixing uranium: Evidences from uranium oxidation state and functional groups of organic matter

IF 3.4 3区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Applied Geochemistry Pub Date : 2025-09-24 DOI:10.1016/j.apgeochem.2025.106575

Fan Zhang , Raymond Michels , Yangquan Jiao , Liqun Wu , Hui Rong , Yang Liu , Jianying Wang

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引用次数: 0

Abstract

Carbonaceous debris (CD) dispersed in sandstones closely coexists with uranium (U) mineralization in the Diantou-Shuanglong and Dongsheng uranium deposits, Ordos Basin, China. The occurrence states of element U within uranium-rich CD were investigated by using X-ray Photoecectron Spectroscopy (XPS), Scanning Electron Microscope (SEM), Electron Microprobe Analysis (EMPA) and Fourier Transform Infrared Spectrometer (FTIR) analyses. The results show that uranium content is up to 200338 ppm, and bears a positive relationship with total organic carbon (TOC). Moreover, U(Ⅵ) and U(Ⅳ) are both detected, and U(Ⅵ) is dominant, accounting for 76.49 %. Uranium minerals mostly occur in cell pores and fractures of CD in the forms of colloidal or fibrous shapes and microsome. Besides, adsorbed state of uranium is partially dispersed in matrix. According to the correlation of TOC and U(Ⅵ) (R² = 0.7), it is thought that a part of U(Ⅵ) is related to absorption of CD, and another part is associated with uranium minerals, which is also supported by the existences of complex uranium oxide detected by FTIR. Moreover, carboxyl group bears a positive relationship with U(Ⅵ). Besides, pyrites are unevenly altered by uranium minerals. The coexistences of autunite and pyrite support that the pyrites have an enhanced effect on the reduction of U (VI) and microbial activities exist. Hence, it is comprehensively that CD directly contributes to uranium precipitation and enrichment, accompanying with the participation of pyrite and microbial activities. Compared with hydroxyl group, carboxyl groupis more favorable for U(Ⅵ) absorption.

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天然有机质在固定铀中的作用：来自铀氧化态和有机质官能团的证据

鄂尔多斯盆地滇头-双龙和东胜铀矿床中，分散在砂岩中的碳质碎屑与铀成矿密切共生。采用x射线光电子能谱（XPS）、扫描电子显微镜（SEM）、电子探针分析（EMPA）和傅里叶变换红外光谱仪（FTIR）分析了富铀CD中U元素的赋存状态。结果表明，铀含量最高可达200338 ppm，与总有机碳（TOC）呈正相关。同时检测到U（Ⅵ）和U（Ⅳ），以U（Ⅵ）为主，占76.49%。铀矿物多以胶状或纤维状及微粒体的形式存在于CD的细胞孔隙和裂隙中。此外，铀的吸附态部分分散在基体中。根据TOC与U（Ⅵ）的相关性（R2 = 0.7），认为一部分U（Ⅵ）与CD的吸收有关，另一部分与铀矿物有关，FTIR检测到的络合物氧化铀的存在也支持了这一观点。羧基与U呈正相关关系（Ⅵ）。此外，黄铁矿受铀矿物的蚀变不均匀。黄钨矿和黄铁矿的共存支持了黄铁矿对U （VI）还原作用的增强和微生物活性的存在。综上所述，CD直接参与了铀的沉淀和富集，并伴有黄铁矿和微生物活动的参与。与羟基相比，羧基更有利于吸收U（Ⅵ）。

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来源期刊

Applied Geochemistry 地学-地球化学与地球物理

CiteScore

6.10

自引率

8.80%

发文量

272

审稿时长

65 days

期刊介绍： Applied Geochemistry is an international journal devoted to publication of original research papers, rapid research communications and selected review papers in geochemistry and urban geochemistry which have some practical application to an aspect of human endeavour, such as the preservation of the environment, health, waste disposal and the search for resources. Papers on applications of inorganic, organic and isotope geochemistry and geochemical processes are therefore welcome provided they meet the main criterion. Spatial and temporal monitoring case studies are only of interest to our international readership if they present new ideas of broad application. Topics covered include: (1) Environmental geochemistry (including natural and anthropogenic aspects, and protection and remediation strategies); (2) Hydrogeochemistry (surface and groundwater); (3) Medical (urban) geochemistry; (4) The search for energy resources (in particular unconventional oil and gas or emerging metal resources); (5) Energy exploitation (in particular geothermal energy and CCS); (6) Upgrading of energy and mineral resources where there is a direct geochemical application; and (7) Waste disposal, including nuclear waste disposal.