【作者】 刘洁；

【导师】 彭志宏； 余侃萍；

【作者基本信息】 中南大学 ， 资源与环境（专业学位）， 2025， 硕士

【摘要】 随着经济发展和产业结构调整的加速推进,有色冶炼工业遗留场地面临的多金属复合污染问题日益严重,已成为制约场地再开发与利用的关键障碍。当前针对冶炼场地多金属污染的阻控研究仍面临诸多挑战,包括污染分布特征不清、多金属同步稳定化效率低下、以及修复材料在复杂环境条件下的适应性不足等问题。我国冶炼场地污染治理普遍存在着重土轻水的问题,重金属在土壤-地下水环境中呈现双向迁移过程,针对单一介质污染的传统修复材料和技术体系已难以满足治理需求。因此,论文以典型冶炼场地为研究对象,明晰冶炼场地重金属污染空间分异特征及其迁移扩散对地下水的潜在影响,同时研发土水协同修复功能材料Ca/Al-LDHs@Fe-BC,并构建土壤-地下水协同修复技术体系,揭示修复材料对多金属同步稳定化机制,进一步探究复杂环境条件下材料的长效稳定性。主要结果如下:（1）研究区域的特征污染物为Pb、Zn、As和Cd,且污染程度依次为Cd>Z>As>Pb。利用自组织映射图SOM与K-means聚类解析,198个土壤样品被划分为6个具有不同分布特征的聚类,其中Pb、Zn、As和Cu呈现相似的分布特征,而Cd和Co的分布模式相似。多重聚类分析表明,土壤类型和场地生产功能分区是影响重金属异质性分布的关键因素。通过分析重金属在土壤胶体中的分配情况,发现深层和表层土壤Cd、Zn、As和Pb在胶体中的占比均超过70%。土壤胶体中方铅矿（Pb S）、锌铁尖晶石（Zn Fe₂O₄）和高岭石是重金属赋存的主要矿物载体,其与类腐殖质和类蛋白质组分,形成无机-有机-重金属复合体,促进重金属跨介质迁移,对地下水质量造成较大污染风险。（2）基于铁改性生物炭（Fe-BC）和层状氢氧化物（Ca/Al-LDHs）,研发土水协同修复材料Ca/Al-LDHs@Fe-BC（LFBC）。LFBC对Zn、As、Cd的最大吸附容量分别达313 mg/g、80.1 mg/g和421 mg/g。在修复材料对Zn、As和Cd复合污染溶液的吸附实验中,所有污染物的去除率均达到90%以上,且选择性吸附顺序为As>Cd>Zn。复合污染土壤添加2.0%(（w/w）的修复材料后,土壤重金属的浸出浓度均降至《地下水环境质量标准》III类标准限值以下,重金属残渣态占比分别提升至20%-77%。稳定化机制解析表明,Zn的稳定化主要通过离子交换、材料表面共沉淀及矿化作用实现;As（V）首先被还原为As（III）,然后通过阴离子交换反应、铁氧基团配位络合共沉淀及材料表面的特异性吸附作用实现稳定化;Cd的稳定化涉及同晶取代、络合沉淀及静电吸附等作用机制。（3）土壤重金属稳定化和地下水抽出处理联用构建土壤-地下水重金属协同修复体系,经过土壤阻隔层后,地下水中Zn、As、Cd去除率分别达95%、96%、和74%,土壤重金属残渣态占比分别提高28%、10%和7.0%,实现土水介质中多金属污染协同阻控。干湿交替和冻融循环通过调控氧化还原条件和土壤理化性质,影响重金属迁移转化过程,经过30次循环后,经LFBC修复的土壤Zn、As、Cd浸出浓度稳定在1.65×10^-1、9.80×10^-3、4.85×10^-3 mg/L以内,说明LFBC修复材料在环境应力作用下具有良好的稳定性。因此,构建土壤-地下水协同修复体系可以有效实现土-水界面多介质污染阻控,为场地综合治理提供科学依据。图43幅,表8个,参考文献158篇更多还原

【Abstract】 Accelerated economic development and industrial restructuring has intensified multi-metal（loid）s contamination at legacy non-ferrous smelting sites,critically impeding their redevelopment and sustainable utilization.Current remediation research faces significant challenges including ambiguous spatial distribution patterns of pollutants,inefficient in multi-metal stabilization,and inadequate adaptability of remediation materials under complex environmental conditions.Remediation efforts at smelting sites in China predominantly focus on soils while neglecting groundwater contamination.Heavy metal（loid）s exhibit dynamic bidirectional transport within the soil-groundwater system,rendering traditional remediation materials and technologies designed for single-medium contamination inadequate.Based on the above challenges,this study focus on a representative smelting site.Key objectives included elucidating heavy metal（loid）s spatial heterogeneity and migration potential to groundwater,developing the novel soil-groundwater co-remediation material Ca/Al-LDHs@Fe-BC,establishing an integrated remediation strategy,revealing the material’s synchronous multi-metal（loid）s stabilization mechanisms,and evaluating its long-term stability under environmentally complex conditions.The main results are as follows:（1）The characteristic pollutants of the smelting site were identified as Pb,Zn,As,and Cd,with contamination severity following the sequence:Cd>Zn>As>Pb.Through integrated Self-Organizing Map（SOM）and K-means clustering analysis,198 soil samples were classified into 6 clusters with different distribution characteristics.Pb,Zn,As,and Cu exhibited similar distribution patterns,while Cd and Co exhibited analogous distribution modes.Multiple-hits analysis indicated that soil types and functional partitions were key factors influencing the heterogeneous spatial distribution of heavy metal（loid）s.Evaluation of heavy metal（loid）s partitioning in soil colloids demonstrated that over 70%of Cd,Zn,As,and Pb in both deep soil and topsoil were colloid-associated.Mineralogical characterization identified galena（Pb S）,franklinite（Zn Fe₂O₄）,and kaolinite as primary carriers for heavy metal（loid）s sequestration within soil colloids.Through interactions with humic-like and protein-like organic substances,these mineral phases generated inorganic-organic-metal（loid）s complexes,which promoted the cross-media migration of contaminants,posing significant contamination risks to groundwater quality.（2）A novel composite material（LFBC）was developed by integrating the structure of iron-modified biochar of iron-modified biochar（Fe-BC）with calcium/aluminum layered double hydroxides（Ca/Al-LDHs）for synergistic soil-groundwater remediation.The LFBC exhibited excellent adsorption properties,with the maximum adsorption capacities reaching313 mg/g for Zn,80.1 mg/g for As,and 421 mg/g for Cd.In multi-metal（loid）s（Zn,As,and Cd）aqueous systems,the material achieved removal efficiencies exceeding 90%for all target contaminants,exhibiting preferential adsorption selectivity:As>Cd>Zn.Soil stabilization experiments revealed that 2%（w/w）LFBC amendment effectively reduced heavy metal（loid）s leaching concentrations below the Class III limits of the“Standard for Groundwater Quality GB 14848-2017”,while increasing residual fraction proportions to 20-77%across contaminants.Analysis of the stabilization mechanism indicates that the stabilization of Zn is mainly achieved through ion exchange,coprecipitation on the material surface,and mineralization.As（V）is first reduced to As（III）,and then its stabilization is realized through anion exchange reactions,coordination and coprecipitation with iron oxide groups,and specific adsorption on the material surface.Isomorphic substitution,complexation precipitation,and electrostatic adsorption are the key action mechanisms involved in the stabilization of Cd.（3）A laboratory-scale simulation device for the synergistic remediation of soil and groundwater was constructed by integrating the soil heavy metal（loid）s stabilization with the groundwater pump-and-treat technologies.This multi-barrier approach achieved significant contaminant interception,demonstrating removal rates of 95%for Zn,96%for As,and 74%for Cd across the soil containment layer.Concomitantly,residual metal fractions in treated soils increased by 28%,10%,and 7.0%respectively,confirming effective multi-compartment pollution containment in both soil and aqueous matrices.Environmental stress testing revealed that redox condition modulation via wet-dry alternation and physicochemical property alterations induced by freeze-thaw cycling significantly influenced metal migration patterns.After 30 cycles,the leaching concentrations of Zn,As,and Cd in the soil remediated by LFBC stabilized within 1.65×10^-1、9.80×10^-3 and 4.85×10^-3 mg/L,respectively,verifying the superior stability of LFBC material through multiple environmental perturbation regimes.Therefore,establishment of a synergistic soil-groundwater remediation system enables effective multi-media contamination containment at the soil-water interface through coupled physical-chemical barrier mechanisms and hydrodynamic regulation,thereby offering a scientific foundation for comprehensive site remediation strategies.更多还原