外源腐植酸与有机矿质复合体界面结合机理及对焦化厂污染土壤中PAHs环境行为的影响

The content of soil organic matter is in the dynamic state along with input、eluviation and biodegradation. However, the effect of exogenous humic acid on the environmental activity of PAHs in soil was seldom studied, and the mechanism should be further explored. Considering the candidate's experience in the previous researches of organomineral complexes, the application of this project is with the purpose for candidate's continual study. Therefore, the red soil and black soil, which are sampled from the coking plants with very different physiochemical properties, will be used to explore the effect of exogenous humic acid on the bound residue, bioavailability and migration of PAHs through the process of peat humification, column leaching, static extraction. Furethermore some research will be focused and performed in comparison of organomineral complexes before and after peat humification, including (1) the changes of polarities, charges, Lewis acidifies and Zeta electric potential on the surface of organomineral complexes, (2) the variance of spectral characteristics of 13C -NMR, FTIR, CLSM, (3) the content changes of bridge bond multivalence metal cation such as Ca2+, Mg2+, Al3+ and Fe3+ in the organomineral complexes and leaching solution.The comprehensive conclusions based on the researches above all will be benefit in further understanding the characteristics and mechanism of exogenous humic acid interaction with mineral, organic matters and PAHs from a micro-interface view. Finally, this project will enrich the research of organomineral complexes and will be in support of the bioremediation of contaminated soils with peat.

土壤有机质含量由于外源输入、淋溶、生物降解等作用而处于动态变化之中，但是外源腐植酸输入对PAHs在土壤中环境行为影响研究相对较少，其作用机理尚不十分清楚。本课题希望利用申请者在污染物在土壤有机矿质复合体方面的研究探索性，选择红壤和黑土两种土壤类型差异较大的焦化厂实际污染土壤，通过泥炭腐化、柱淋溶和静态提取实验，研究外源腐植酸对PAHs结合残留、生物可利用性、迁移特性的影响；根据泥炭腐化前后有机矿质复合体的表面位、荷电性、Zeta电位等变化，结合固态核磁共振(13C-NMR)、红外光谱(FTIR)、激光共聚焦显微(CLSM) 光谱特征，以及矿质复合体和淋溶液中Ca2+、Mg2+、Al3+、Fe3+多价"桥键"金属含量的变化，初步探索外源腐植酸与矿物质-有机质-PAHs在微观界面上的结合特征和作用机理，为丰富有机矿质复合体研究和泥炭用于污染土壤修复提供一定的理论支持。

以北京焦化厂的土壤为研究对象，选取了PAHs污染浓度梯度差异较大的土壤样品，利用IHSS的方法对胡敏素、胡敏酸和富里酸分别进行提取与纯化，测试PAHs在土壤不同组分中的分布规律，同时利用XAD-2树脂辅助解吸技术探究PAHs在土壤及胡敏素中的解吸特征和生物有效性，并比较了土壤样品、胡敏素样品解吸前后的红外光谱差异，实验结果显示：PAHs 有效性与初始含量之间具有显著的线性相关性，SOM含量的增加会带来生物有效性的降低，低环芳烃的生物有效性略高于高环芳烃。土壤的腐殖质化程度与PAHs的污染浓度呈正相关性，胡敏素中PAHs的含量最多，是土壤有机质与PAHs的主要结合部位。胡敏素中PAHs解吸分为快、慢两个阶段，其累计解吸率随着苯环数的增高而降低，红外分析表明PAHs解吸过程不改变土壤有机官能团类型，吸附于羟基及羧基上的PAHs更易解吸，但官能团含量减少。. 添加了一定量的胡敏酸（2g土壤样品添加30mg的胡敏酸干粉），土壤对不同环数多环芳烃固定作用均增强，对高环PAHs固定效果高于低环，其作用机理与内源胡敏酸相一致。采用前向选择和蒙特卡洛显著性检验对土壤性质和腐殖酸形态影响土壤中多环芳烃生物可给性的重要性进行排序，结果如下：粉粒 > 湿度 > 酸度 > 有机溶剂可提取态的PAHs > 富里酸结合态的PAHs > 粘粒 > 有机质 > 总氮 > 胡敏酸-矿物质结合态PAHs > 总磷 > 胡敏酸结合态 > 干酪根结合态 > 胡敏酸结合态PAHs，并且外源胡敏酸与土壤矿质相结合后，对土壤中PAHs环境行为影响大于单独作用结果，而外源富里酸的加入可能会引起土壤中多环芳烃移动性和生物可利用性提高。