沉积物的重金属污染是影响水环境安全与生态健康的重要因素，控制沉积物中重金属的扩散和稳定是水生态修复的重要措施。在水体沉积物中，重金属的释放、扩散和形态变化是其环境行为的主要表现形式，研究该过程的影响因素、控制技术和相关机理，可为重金属污染沉积物的治理工作提供理论依据和技术支撑。因此，本文基于生物炭的应用，以沉积物中重金属扩散的控制和稳定性的提高为目的，通过室内沉积物淋滤实验、重金属吸附实验、覆盖阻断实验及沉积物重金属稳定实验，借助光谱、能谱、化学分析等手段，开展生物炭修复重金属污染（Cu、Pb、Zn）沉积物的研究。得出主要结论如下： （1）揭示了水环境变化对沉积物中Cu、Pb、Zn释放及稳定性变化的影响。不同水质参数（pH、Cl-、PO43-、NO3-和腐殖酸）对沉积物中Cu、Pb、Zn的影响差异较大，pH值降低和Cl-浓度增加可促进Cu、Pb、Zn的释放，但在pH=12的条件下，由于发生碱式消解使有机质含量降低，可导致Cu的释放量增加；PO43-可降低沉积物中Cu、Pb、Zn的释放并提高其在沉积物中的稳定性；腐殖酸降低了Cu的稳定性，但对Pb和Zn稳定性的影响较小；而NO3-对Cu、Pb、Zn在沉积物中的迁移转化行为影响不明显。 （2）探究了由木屑、秸秆和污泥制备的生物炭（分别以MX、JG、WN表示）对重金属Cu、Pb、Zn的吸附特性。三种生物炭对Cu、Pb、Zn的吸附属于吸热过程，吸附反应在10~16小时之间可达到平衡，随温度和pH升高，MX、JG、WN对Cu、Pb、Zn的吸附容量逐渐升高；由于柠檬酸含有羟基和羧基结构，可为重金属提供吸附点位，在低浓度下（≤2.5 mg/L）被生物炭吸附能提高生物炭对Cu、Pb、Zn的吸附量；而络合作用和竞争吸附是柠檬酸（＞2.5 mg/L）和草酸（0~50 mg/L）降低生物炭吸附量的主要原因。总体上，在室温下JG对Cu的饱和吸附量最大，约为70.2 mg/g；MX对Pb和Zn的饱和吸附量最大，分别为674.4和86.3 mg/g左右；而WN对Cu、Pb、Zn的饱和吸附量最小，均小于50 mg/g。 （3）建立了生物炭对沉积物重金属（以Cu、Zn为例）扩散的阻断作用与其吸附量、滞留系数（Ri）及重金属扩散系数（Di）的关系。由于秸秆生物炭（JG）对Cu的吸附量大于木屑生物炭（MX），对Cu的阻断作用JG>MX，而对Zn的作用与Cu相反，MX>JG；根据菲克定律建立的扩散模型，其模拟结果与实验观测值具有较高的一致性。分析结果表明，扩散系数Di对Cu、Zn在JG中扩散的影响相对于滞留系数Ri更敏感；Cu和Zn穿透JG覆盖层的厚度随时间逐渐增加，但由于DCu,JG>DZn,JG，穿透同一JG层厚度所需的时间Cu>Zn；实验条件下，Cu穿透30 cm厚度JG需要大概183年，Zn则需要406年左右。 （4）探究了木屑生物炭（MX）、秸秆生物炭（JG）、污泥生物炭（WN）对沉积物重金属（Cu、Pb、Zn）稳定性的促进作用。与空白对照相比，在混合生物炭后，沉积物（RI）中Cu、Pb、Zn的梯度扩散膜提取浓度（CDGT）和毒性浸出浓度（CTCLP）随生物炭添加量增加明显降低，在10 %生物炭添加量下，均降低了近70 %；形态分析（BCR）也表明，在2.5 %~10 %生物炭添加量下，RI中Cu和Pb的可氧化态（F3）和残渣态（F4）比例上升了2.6 %~78.3 %，Zn的弱酸提取态（F1）下降了3.3 %~15.4 %，受三种生物炭影响，Cu、Pb、Zn的稳定性均有所提高；另外，研究还发现，WN对重金属的吸附量低于MX和JG，但三种生物炭对沉积物金属稳定性影响的差异性并不明显，所以吸附不是唯一的稳定作用机理。 （5）提出了“生物炭-Fe-重金属三元体系”对沉积物重金属稳定性促进的作用机理。生物炭的添加提高了沉积物中无定形Fe氧化物的比例，使其活化度升高了20.3 %~120.1 %，可改善Fe氧化物对重金属的吸附性能；同时，游离态Fe被生物炭吸附固定，导致游离度降低了8.2 %~18.2 %，促进了游离态Fe向结构态Fe的转变，进而提高了与Fe结合的重金属的稳定性；构成的“生物炭-Fe-重金属三元体系”是沉积物重金属稳定性增强的重要机理之一。

The heavy metal contamination in sediments is an important factor to influence water safety and ecological health. Controlling heavy metals diffusion and stability in sediment is a significant measure to improve water ecological environment. In aquatic and sediment system, release, diffusion and speciation transformation are the important behaviours of heavy metals. Study releted influence factors, controlling technologies and mechanisms can provide theoretical foundation and technical support for contaminated sediments remediation. Therefore, this study use bichar as the amendment to remedy heavy metal contaminated (Cu, Pb and Zn) sediment with the view to controlling heavy metals diffusion and improving its stability. According to leaching, adsorption, capping and stabilization experiments, and the analysis of spectrum, energy spectrum, chemistry method and so on, the main results obtained are summarized as follows: （1）The effect of water environmental changes on releasing of Cu, Pb and Zn and their stability in sediment has been revealed. There are great different between the effect of pH、Cl?、PO43-、NO3- and hunmic acid on the behaviors of Cu, Pb and Zn. Expect of Cu at the leaching condition of pH=12 occuring alkali dogesttion, reducing organic content and releasing more Cu, the accumulation release content of Cu, Pb and Zn increase with declining pH value and increasing Cl? concentration; PO43+ can decrease heavy metals releasing and enchance their stability; humic acid decreas the stability of Cu but have little effect on Pb and Zn; moreover, NO3- have no obvious effect on heavy metals’ migration and transformation in sediment. （2）The adsorption characteristic of sawdust biochar (MX), straw biochar (JG) and sludge biochar (WN) for Cu, Pb and Zn have been studied. The process of adsorption is endothermic reaction as adsorption capability of biochar increase with temperature and pH rasing, and the adsorption equilibrium can be reached whitin 10-16 hours. At the lower concentration (≤ 2.5 mg/L), the citric acid can provide adsorption position for heavy metals and promote biochar adsorption capability, whereas due to complex function and competition citric acid and oxalic acid can reduce biochar adsorption capability at the concentration over 2.5 and 0~50 mg/L, respectively. Generally, the adsorption capacity of JG for Cu is the largest with about 70.2 mg/g, and the adsorption capacity of MX for Pb and Zn are the largest with about 674.4 and 86.3 mg/g, respectively, whereas WN have lower adsorption capacity for Cu, Pb and Zn than JG and MX with all bellow 50 mg/g. （3）The releationship between interruption heavy metals diffusing and adsorption capability, retardation factor (Ri) and diffusion coefficient (Di) of biochar have been studied. Due to the adsorption capacity for Cu is JG>MX, the retention efficiency for Cu is JG> MX, but it is opposite for Zn. Based on the Fick's second law, the simulation results have a well correlation with observed value, and the Di have more siganificant effect on heavy metals diffusion than Ri. According to model prediction, the penetrating thickness of Cu and Zn in JG increase with time. Due to DCu,JG>DZn,JG, it consume more time for Zn to penetrate a certain thickness of JG than Cu. So, 183 years are need for Cu to pass through 30 cm JG, whereas that for Zn are 406 years. （4）The effect of MX, JG and WN on heavy metals’ stability in sediment have been studied. Compared to the blank, after mixture with biochar the Cu, Pb and Zn concentration of diffusive gradient in thin films (CDGT) and toxicity ctharacteristic teaching procedure (CTCLP) decrease in sediment (RI) with adding more biochar. At 10 % dosage, the CDGT and CTCLP decrease about 70 %. According to speciation analysis (BCR), at 2.5 %~10 % dosage the oxidizable fraction (F3) and residual fraction (F4) for Cu and Pb increase about 2.6 %~78.3 %, whereas the acid soluble fraction (F1) for Zn decrease about 3.3 %~15.4 %. The stability of Cu, Pb and Zn have been imporved by biochar. Moreover, although the adsorption capacity of WN was lower than MX and JG, the stability efficiency of MX, JG and WN have no obviously different, the adsorption was not the only stabilization mechanism. （5）The mechanism of “Biochar-Fe-Heavy Metals Ternary System” to promote heavy metals’ stability has been raised. The biochar can enchance the proportion of Fe-oxide increasing its activity 57 %~120 % which can improve its adsorption property. Meanwhile, free Fe can be adsorbed by biochar decreasing its freeness 8.2 %~18.2 %, promoting the transformation of Fe from free speciation to structural speciation and then improving the stability of those heavy metals bound with Fe. The biochar-Fe-heavy metals ternary system is one of the important stabilization mechanism.