石油污染包气带碳稳定性与微生物作用效应研究

Soil contamination by the crude oil in the vadose zone has drawn great attention due to its ecological risks and environmental safety concerns. The key is the organic component of the petroleum hydrocarbon, the carbon stability, microbial interactions and their effects on the structure and function of the contaminated soil. In this proposal, we select the typical crude oil exploitation area in the eastern part of China as the subject, and investigate the soil carbon stability and microbial interactions in the vadose zone under the stress of oil contamination, using advanced analytical techniques such as isotope analysis, metagenomics, high resolution mass spectroscopy, nuclear magnetic resonance (NMR), etc. From the perspective of soil carbon structure and component, we investigate the dynamics of the soil carbon stability under contamination, understand the internal relationship among contamination level, contaminant component and the carbon stability. We evaluate the effect of soil contamination on the emissions of carbon dioxide and methane, reveal the spatial and temporal variations of carbon emissions, and investigate the relationship between the carbon emission pathway and the carbon component. Based those results, we will further study the dynamics of the microbial community and functional genes, identify the interactions between microbial community and carbon stability, and construct the multi-factor model for the evaluation of carbon stability. The research outcome will provide insights to the carbon stability mechanisms and foundations for the identification of ecological risks in the oil exploitation area under the stress of crude oil contamination.

包气带石油污染土壤所引起的生态风险和环境安全问题受到高度关注，石油烃类等有机碳组分构成、稳定性与微生物作用效应对于污染土壤结构、功能和污染物归宿的影响成为关键研究内容。项目选择我国东部典型石油开采区作为研究区，利用同位素示踪、宏基因组学、高分辨质谱、核磁共振等现代分析技术方法，开展石油污染包气带土壤碳稳定性与微生物作用效应研究。从土壤碳物理结构和分子组成的角度，精细刻画石油污染条件下土壤碳稳定性的变化特征，构建土壤污染程度、污染物构成与碳稳定之间的内在关系；评估石油污染对区域土壤CO2和CH4释放规律的影响，揭示污染土壤碳释放时空动态变化，解析污染土壤碳排放途径与碳构成之间的关系；探讨石油污染土壤微生物群落及功能基因变化，识别微生物群落与土壤碳稳定性关系，构建污染土壤碳稳定性的多因子量化模型。研究成果将为油田区污染土壤碳稳定性机制和生态风险识别提供理论基础与方法支撑。

包气带石油污染土壤所引起的生态风险和环境安全问题受到高度关注，石油烃类等有机碳组分构成、稳定性与微生物作用效应成为关键研究内容。项目选择我国不同地理位置的油田作为典型研究区，利用稳定同位素、高分辨质谱、高通量测序技术和功能基因芯片等现代分析技术方法，研究石油污染包气带土壤碳稳定性与微生物作用效应。基于土壤碳物理结构和分子组成研究，刻画了石油污染条件下土壤碳稳定性的变化特征。研究结果表明，石油污染土壤粗大团聚体、孔隙直径、平均重量直径（MWD）和标准化平均重量直径（NMWD）显著增加，微团聚体显著减少。污染土壤饱和烃的长碳链组分增加，但是腐殖化程度降低，表明石油污染土壤碳物理和化学稳定性都降低。评估了石油污染对区域土壤CO2和CH4释放规律的影响，揭示污染土壤碳释放时空动态变化，解析污染土壤碳排放途径与碳构成之间的关系。结果表明：石油污染土壤碳释放量（74 ± 80 mg·m–2·h–1）显著低于未污染土壤（658 ± 537 mg·m–2·h–1, P < 0.05），其中CO2通量显著减少，CH4通量显著增加，说明石油污染土壤的好氧微生物降解产CO2的过程受到抑制，而厌氧降解产CH4过程增强。探讨了石油污染土壤微生物群落及功能基因变化，发现污染土壤中跟CO2释放有关的功能基因数量、丰度、多样性和互作关系减少；而产甲烷菌相对丰度显著增加，是未污染土壤的8倍；污染土壤同位素分馏因子（1.031~1.042）增加表明，氢营养型产甲烷途径的贡献率增加。微生物群落与土壤碳稳定性关系研究表明，石油污染土壤CO2释放量跟好氧菌数量、代谢活性和碳降解基因丰度呈显著正相关；CH4释放通量与产甲烷菌丰度呈显著正相关。基于约束性排序分析和变量分解分析表明，土壤微生物群落结构指标与理化性质，对于土壤碳稳定性变化的共同解释程度达到91%（P < 0.001），表明微生物和土壤结构特征共同影响碳稳定性。利用结构方程SEM模型构建了土壤碳转化的多因子量化模型。研究成果为油田区污染土壤碳稳定性机制奠定理论与方法基础。