基于同步辐射技术研究锌在废弃稀土矿区土壤中的吸附及垂向迁移特征  

Adsorption and Vertical Migration Characteristics of Zinc in Soil from Abandoned Rare Earth Mine Using Synchrotron Radiation-Based Technique

作　　者：李洋 欧丽 黄琨[1] 刘鹏 刘燕红 李曼曼 唐金平 Li Yang;Ou Li;Huang Kun;Liu Peng;Liu Yanhong;Li Manman;Tang Jinping(College of Environment,China University of Geosciences,Wuhan 430074,China;Ecological Environmental Monitoring Centre of Jiangxi Province,Nanchang 330039,China)

机构地区：[1]中国地质大学环境学院,武汉430074 [2]江西省生态环境监测中心,南昌330039

出　　处：《吉林大学学报(地球科学版)》2025年第1期233-244,共12页Journal of Jilin University:Earth Science Edition

基　　金：江西省工业园区地下水监测管控网络体系建设示范项目(JXMD2022-Z002);中央环保投资储备库项目(2022B000563260)。

摘　　要：为了研究锌(Zn)在赣南稀土矿区土壤的吸附及垂向迁移特征,以及为矿山开采地区土壤及水体Zn污染防治、修复及风险评估提供理论依据,首先采用静态批实验,研究某废弃稀土矿区垂直剖面不同深度土壤对Zn的吸附特征;然后采用X射线衍射(XRD)及X射线吸收谱(XAFS)研究土壤主要物相组成及土壤中Zn的赋存形态变化,探讨Zn在土壤中的吸附机制及可迁移性。结果表明:剖面3层土壤对Zn的吸附平衡过程较快,土壤对Zn的吸附能力呈现出从表层土到深层土再到中层土逐渐减弱的趋势,准二级动力学模型及Langmuir方程能较好地描述土壤吸附Zn的过程;元素Fe、Mn在土壤中主要以Fe的氢氧化物及混合价态锰氧化物形式存在,剖面各层土壤理化性质差异影响土壤对Zn的吸附行为,相比于黏土矿物,Fe、Mn氧化物对土壤吸附Zn的影响更加显著;吸附反应前后土壤中Zn的局部配位模式由Zn-O四面体转变为Zn-O四面体和八面体的混合配位模式,反应后土壤表面可能形成了类似硫酸盐的外层络合物,反应前后土壤中的Zn由碱式碳酸盐转变为以硫酸盐与碱式碳酸盐的混合形式存在;受土壤pH影响,土壤滞留Zn能力有限,土壤中的有效态Zn易伴随降雨冲刷向下层土壤迁移,土壤中Zn质量分数随深度增加而增加。This study focuses on the adsorption characteristics of zinc in soil at different depths of a certain abandoned rare earth mine in the south of Ganzhou,Jiangxi Province.Static batch experiments were conducted.X-ray diffraction(XRD)and X-ray absorption fine structure spectroscopy(XAFS)were used to study the major phases and morphological changes of zinc in soil before and after adsorption reaction,in order to investigate the adsorption mechanism and mobility of zinc in soil.The results show that the adsorption equilibrium process of zinc in soil is fast.The adsorption capacity of soil for zinc gradually decreased from the surface soil to the deep soil and then to the middle soil.The pseudo-second-order kinetic model and Langmuir equation can describe the adsorption process of zinc in soil well.XRD and XAFS results show that iron and manganese exist mainly in the form of iron hydroxide and mixed valence state manganese oxide in soil.Differences in the physical and chemical properties of soil layers affect the adsorption behavior of soil towards zinc.Compared with clay minerals,iron and manganese oxides have a more significant effect on the adsorption of zinc in soil.XAFS indicates that the local coordination mode of zinc changes from Zn-O tetrahedron to a mixed coordination mode of Zn-O tetrahedron and octahedron after adsorption reaction.A complex similar to sulfate may form on the soil surface after the reaction.The form of zinc in soil changes from basic carbonate to a mixed form of sulfate and basic carbonate after adsorption reaction.Due to the influence of soil pH,the capacity of zinc retention in soil is limited.The readily available zinc in soil is prone to migrate downward with rainfall.The zinc content in soil increases with depth.The study provides a scientific basis for the prevention and control of zinc pollution in soil and groundwater in mining areas.

关 键 词：土壤 锌 吸附 迁移 X射线吸收谱 稀土矿区 同步辐射 

分 类 号：X53[环境科学与工程—环境工程]