多环芳烃（PAHs）及其衍生物（SPAHs）等多环芳族化合物（PACs）因其高毒性、难降解性等特点成为国际社会长期关注的研究热点。石油污染是土壤环境PACs污染物的重要来源之一，因此，开展石油污染土壤修复研究，去除PAHs、SPAHs，对改善土壤环境质量、保护人类健康具有重要意义。近年来，生物炭在改善土壤性质、修复土壤污染等方面发挥重要作用而引起国内外学者高度关注，然而目前采用生物炭基降解菌剂修复石油污染土壤PACs的研究鲜有报道，生物炭菌剂强化修复下微生物响应机制尚未阐明。本文对稻壳、竹屑和玉米秸秆生物炭分别进行酸碱处理制备改性生物炭，通过表征生物炭材料性质，结合批量吸附实验探讨生物炭吸附性能和机理，比选确定菌剂最佳固定化载体；筛选高效降解菌，采用吸附法和包埋法制备生物炭基降解菌剂，探究菌剂降解性能与机理，确定适用于污染土壤强化修复的固定化菌剂；以胜利油田污染土壤为研究对象，选取16种PAHs和典型SPAHs（氧化PAHs（OPAHs）、硝基PAHs（NPAHs））为目标污染物，探究土壤PAHs和N/O-PAHs赋存状态及污染胁迫下土著微生物群落结构和功能特征，基于分子生态网络和相关性分析解析原位污染土壤细菌、古菌和真菌组装模式与驱动因素，揭示污染土壤自然衰减潜力；基于制备的生物炭菌剂及实际污染场地土壤，开展180天修复实验，探讨菌剂强化修复石油烃污染土壤PAHs和N/O-PAHs性能，揭示菌剂强化修复过程中土壤细菌、古菌和真菌群落响应机制。主要研究成果如下：

（1）硝酸改性提升了生物炭比表面积，去除了生物炭上的方解石等杂质，增加了羟基（-OH）、羰基（C=O）、羧基（-COOH）、芳香族C-H键、C=N键、Si-O键等表面官能团。酸改性稻壳生物炭DH孔径清晰、结构完整。吸附实验表明，DH对菲的吸附量最大（3818.99μg·g^-1）。生物炭对菲的吸附过程更符合准二级动力学模型，表明吸附过程主要受化学作用主导；等温吸附曲线较好地符合Freundlich等温吸附模型，表明吸附主要发生在非均匀表面。有机污染物与生物炭之间的孔隙截留、氢键作用、疏水作用、π-π、n-π和静电作用等是菲在生物炭上吸附的主要作用机制。经比选，酸改性稻壳生物炭DH更适合作为固定化菌剂的载体。

（2）筛选到高效降解菌Rhodococcus sp. DG1，采用吸附法制备出粉末状生物炭基降解菌剂DD，采用包埋法制备出生物炭基降解菌小球DDQ，确定了最佳制备条件。固定化菌对人工污染土中菲的降解去除效率明显高于游离菌，粉末状生物炭基降解菌剂DD的降解效果最好，30天内对菲的降解去除率达到80.15%，而生物炭基降解菌小球DDQ由于传质受限，降解效果低于粉末状菌剂DD。菌剂对土壤中菲的降解过程符合一级反应动力学模型，固定化作用提高了降解菌对菲的降解速率。扫描电镜观察到生物炭基降解菌剂DD表层均匀致密的细菌层，证明菌株Rhodococcus sp. DG1成功地附着在生物炭表面且遵循生物膜形成模式。吸附-降解过程是固定化菌剂强化修复土壤污染物的主要机理。粉末状生物炭基降解菌剂DD被选择用于土壤PACs强化修复实验。

（3）该油田污染场地PACs含量较高（3429 μg·kg^-1 – 6071 μg·kg^-1），苯并[a]芘含量超过风险值。检测到大量PACs降解菌，包括细菌Proteobacteria、Actinobacteriota、Chloroflexi、Gemmatimonadota和Acidobacteriota，古菌Crenarchaeota，真菌Ascomycota等，以及大量与PAH（KO00624）和NAP（KO00626）降解通路直接相关的降解基因，说明污染土壤具有自然衰减的潜力。分子生态网络分析表明，域间微生物群落组装模式是非随机的，物种间具有强烈的正相关关系和较强的生态联系，分为5个主要功能模块，模块中的功能微生物主要参与有机物和矿物质组分降解、生物电子转移和营养循环等过程。细菌Marinobacter和真菌Neocosmspora是维持网络微生态功能的关键物种。苯并[g,h,i]芘、二苯并[a,h]蒽、茚二酮[1,2,3-cd]苝和总磷是污染胁迫下微生物群落组装和功能的关键驱动因子。

（4）粉末状生物炭基降解菌剂DD对污染土壤PACs具有良好降解性能，180天内对PAHs和SPAHs的降解去除率分别为70.53%和38.22%。低分子量PAHs的降解去除率高于高分子量PAHs；OPAHs的降解去除率高于NPAHs。在修复过程中由于发生了氧取代反应，使OPAHs的含量得到积累。在粉末状生物炭基降解菌剂DD作用下土壤中PACs降解去除率的增加与PACs降解微生物和功能基因的富集有关。细菌群落多样性对强化修复措施的响应更加敏感，不同处理和不同时间下组间差异显著。在群落组成上，细菌在修复初期变化明显，但后期趋于稳定，真菌在整个修复期间都表现出较大波动，而古菌群落组成一直较为稳定。域间分子生态网络是非随机组装的，具有紧密的连通性。修复初期的分子生态网络稳定性更高、种间互作共生关系更紧密，而修复后期资源与生态位竞争逐渐出现。细菌和真菌是网络最主要的关键类群，在维护生态群落的结构和功能中发挥关键作用。土壤有效钾、有效氮、总氮、有效磷、低分子量PAHs和NPAHs是强化修复过程中总体微生物群落组装和演替的主要环境驱动因子。

Polycyclic aromatic hydrocarbons (PAHs) and their derivatives (SPAHs) of polycyclic aromatic compounds (PACs) have been the focus of international research for a long time because of their high toxicity and difficult degradation. Petroleum pollution is one of the important sources of PACs pollutants in soil environment. Therefore, it is of great significance to carry out remediation on petroleum contaminated soil and remove PAHs and SPAHs, which can improve soil environmental quality and protect human health. In recent years, biochar has played an important role in improving soil properties and remediation of soil pollution, which has attracted great attention from scholars. However, there are few reports on remediation of PACs in oil-contaminated soil with biochar-based degradation agents, and the microbial response mechanism under enhanced remediation of biochar agents has not been clarified. In this study, rice husk, bamboo scraps and corn straw were used as raw materials for biochar preparation and acid-base modification. By characterizing the properties of biochar material, combining with batch adsorption experiment, the adsorption properties and mechanism of biochar were discussed, and the optimal immobilized carrier of bacteria agent was determined by comparison. Effective degradation bacteria were screened, biochar-based degradation agent was developed by adsorption and embedding methods, and the degradation experiment of phenanthrene was conducted to reveal the degradation performance and mechanism of the agent, and immobilized bacteria suitable for enhanced remediation of contaminated soil were determined. Sixteen kinds of PAHs and typical SPAHs (oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs)) were selected as the target pollutants in the contaminated soil of Shengli Oilfield to explore the occurrence characteristics of soil PAHs and N/O-PAHs and the structure and function characteristics of indigenous microbial community under pollution stress. Based on co-occurrence network and correlation analysis, the assembly patterns and driving factors of bacteria, archaea and fungi in in-situ contaminated soil were analyzed to reveal the natural attenuation potential of soil pollution. Based on the biochar-based degradation agent and the contaminated soil of the site, 180 days of remediation experiment was carried out to investigate the performance of microbial agents to enhance the remediation of PAHs and N/O-PAHs in petroleum hydrocarbon contaminated soil, and to reveal the response mechanism of soil bacteria, archaea and fungi communities during the enhanced remediation process. The main research results are as follows:

(1) The specific surface area of biochar was improved by acid modification, the impurities such as calcite were removed from biochar to a large extent, and the surface functional groups (hydroxyl (-OH), carbonyl (C=O), carboxyl (-COOH), aromatic C-H, C=N, Si-O, etc.) were increased. DH has a clear aperture and complete structure. The adsorption experiments showed that DH had the highest adsorption capacity of phenanthrene (3818.99 μg·g^-1). The adsorption process of biochar for PHE was more consistent with the pseudo-second order kinetic model, indicating that the adsorption process was mainly controlled by chemical action. The isothermal adsorption process accords well with Freundlich isothermal adsorption model, indicating that the adsorption mainly occurs on non-uniform surface and complex physico-chemical adsorption process. The interaction of pore, hydrogen bond, hydrophobicity, π-π, n-π and electrostatic between organic pollutants and biochar is the main mechanism of PHE adsorption on biochar. The acid-modified rice husk biochar DH is more suitable as the carrier of immobilized bacteria.

(2) Rhodococcus sp.DG1 with high degradation efficiency was screened, degradation agent DD was prepared by adsorption method, degradation agent DDQ was prepared by embedding method, and the optimum preparation conditions were determined. The immobilized bacteria could degrade phenanthrene significantly, and DD had the highest degradation rate of phenanthrene. The degradation efficiency of immobilized bacteria was significantly higher than that of free bacteria. The degradation efficiency of powdered bacteria DD was the best, and the degradation efficiency reached 80.15% within 30 days. However, the mass transfer of DDQ pellet was limited. The degradation process of phenanthrene in contaminated soil was in accordance with the first-order kinetics model, and the immobilization increased the degradation rate of phenanthrene by DG1. The uniform and dense bacterial layer on DD surface was observed by scanning electron microscopy, which proved that strain DG1 was successfully attached and immobilized on the surface of biochar and followed the pattern of biofilm formation. The adsorption-degradation process is an important mechanism for immobilized bacteria to enhance the remediation of soil or solution contaminants. The powdered bacteria agent DD was selected for the enhanced remediation test of PAC in contaminated soil.

(3) The content of the typical PACs in the contaminated site was high (3429 μg·kg^-1–6071 μg·kg^-1), and the content of BaP exceeded the risk value. A large number of PACs degraders were detected, including Proteobacteria, Actinobacteriota, Chloroflexi, Gemmatimonadota, Acidobacteriota, Crenarchaeota and Ascomycota et al. A large number of degradation genes directly related to PAH (KO00624) and NAP (KO00626) degradation pathways were also identified. Network analysis showed that the interdomain microbiome had a non-random assembly pattern and a strong positive correlation between species. The network has strong ecological links and is divided into five main functional modules, in which the functional microorganisms are mainly involved in the degradation of organic and mineral components, bioelectron transfer and nutrient cycling. Marinobacter of bacteria and Neocosmspora of fungi are network keystone species. In addition, benzo[g,h,i]pyrene, dibenzo[a,h]anthracene, indodione[1,2,3-cd]perylene and total phosphorus are key drivers of microbial community assembly and functional patterns under pollution stress.

(4) Powdered biochar agent DD had good degradation performance for PACs in contaminated soil, and the removal rates of PAHs and SPAHs were 70.53% and 38.22% within 180 days, respectively. The degradation and removal rate of low molecular weight PAHs was higher than that of high molecular weight PAHs. The degradation ability of OPAHs is higher than that of NPAHs. Oxygen substitution reaction may occur in the process of microbial and biochar repair, resulting in the accumulation of OPAHs. The increase of PACs degradation removal rate was related to the enrichment of PAC-degraded microorganisms and functional genes. The alpha diversity of bacterial community was more sensitive to intensive repair measures, and there were significant differences between groups under different treatments and different time. In terms of community composition, bacteria changed significantly in the initial stage of restoration, but tended to be stable in the later stage. The composition of fungal community fluctuated greatly in the early and late stages of restoration. The composition of the archaea community remained stable throughout the restoration period. The interdomain molecular ecological network based on bacteria, archaea and fungi community is non-random and has close connectivity. In the early stage of restoration, the network had higher stability and closer interspecific symbiosis, while in the later stage, the community structure might be simpler due to resource competition. Bacteria and fungi are the most important key groups in interdomain molecular ecological network, which play a key role in maintaining the structure and function of ecological community. For the total microbial community, soil physicochemical factors and pollution factors (PACs) together explained 16% of the variance of the microbial community. AK, AN, TN, AP, LMW PAHs and NPAHs were the main driving factors of microbial community assembly pattern and succession during the enhanced restoration.