中碱性农田土壤的镉（Cd）污染已经引起了社会的广泛关注，开展污染土壤的修复与治理迫在眉睫。但是，修复材料的缺乏制约了土壤修复工作的开展。硫铁改性生物炭（S-Fe@Biochar）是一种潜在的土壤Cd稳定化材料。然而，有关该材料对土壤Cd稳定化的作用机制和驱动因子尚缺乏深入系统的研究。基于此，本项目立足前期研究工作，在研发并优化S-Fe@Biochar的基础上，采用批试验、培养试验与盆栽试验相结合的方法并利用现代光谱分析技术，解析材料与溶液中Cd2+的微界面化学过程；剖析生物炭氧化过程中Cd2+与材料组分的微界面作用机制；揭示材料稳定化中碱性土壤中Cd的作用机制和驱动因子并评估材料对污染土壤的修复效果。从而提出基于S-Fe@Biochar表面特性—土壤Cd形态/有效态耦合作用的污染土壤修复理论。这对完善重金属污染农田土壤稳定化修复的理论体系，保障区域土壤环境质量与农产品安全等均具有重要意义。

Nowadays, cadmium (Cd) contamination of neutral-alkaline agricultural soils has attracted public attention. Meanwhile, the remediation of Cd-contaminated agricultural soils has become the priority of current environment protection works for both authorities and scientific institutions. However, the scarcity of effective immobilization agents significantly restricted the conduction of such works. Recently, the sulfur-iron modified biochar (S-Fe@Biochar) has been regarded as a promising candidate for soil heavy metal immobilization. However, mechanisms of Cd stabilization under the influence of this reagent in either short or long terms are still unclear. Therefore, in this study, the influence of S-Fe@Biochar on Cd immobilization in neutral-alkaline soils will be investigated following the combined methods (including batch adsorption experiment, incubation experiment, and pot experiment) and characterized using novel spectrum analysis techniques. The whole work can be divided into three parts: 1) investigating the interface interaction between Cd2+ and S-Fe@Biochar in aqueous solutions; 2) exploring the influence of simulated biochar oxidation on the reaction between Cd2+ and S-Fe@Biochar, and 3) analyzing the effect of S-Fe@Biochar on Cd immobilization in neutral-alkaline soils. The aim of the study is 1) to indicate the mechanism of S-Fe@Biochar on Cd immobilization in neutral-alkaline soils; 2) to specify the reaction process, driving factors, and mechanisms between Cd2+ and S-Fe@Biochar in both short and long terms; and 3) to develop a soil remediation theory based on the relation between S-Fe@Biochar and Cd mobility/specification in soils. The successful completion of this project will supplement soil heavy metal stabilization theory, expand biochar environmental application, and be meaningful for guaranteeing soil quality, food safety as well as reducing the threat of Cd to human beings.