激光诱导荧光检测土壤中PAHs的基础理论和关键技术研究

At present, the detection methods of polycyclic aromatic hydrocarbons (PAHs) in the soil depend basically on sampling test in the laboratory, which cannot meet the demands of the comprehensive evaluation on pollution of PAHs in soil throughout the country. A rapid detection of PAHs in soil is put forward and established based on laser-induced fluorescence in this project. A systematical study is made of the key technologies and methods to provide a new detecting perspective and technology for the rapid evaluation of PAHs in soil. The fluorescence characteristics of 8 PAHs in soil are studied using the technology of two-dimensional correlation spectroscopy. Furthermore, the database of fluorescence characteristics of 8 PAHs in soil is established and the excitation light sources (laser) are selected. Then, the mechanism and regulation of the effect of soil physical and chemical parameters on PAHs fluorescence are studied. With soil physical and chemical parameters as their joint, the relationship between laser-induced fluorescence and visible/near infrared diffuse reflectance spectroscopy is investigated. Furthermore, two-level correction methods are established to reduce or eliminate the effect of soil physical and chemical parameters on PAHs fluorescence. Based on that, 8 PAHs in Dagang soils of Tianjing is detected using laser-induced fluorescence and compared with the results of high performance liquid chromatography. The effectiveness of the proposed methods is verified. Finally, the effects of the soil samples complexity, PAHs trace, experiment condition on the detection limits of 8 PAHs are explored to achieve optimization of the proposed methods. Based on aforementioned study, this project can provide the theoretical and experimental basis for in situ assessment of PAHs pollutions using laser-induced fluorescence.

目前土壤中多环芳烃（PAHs）检测方法，基本都依赖于实验室的取样检测，无法满足全面评价全国土壤污染状况的需求。本项目提出并建立一种基于激光诱导荧光的土壤中PAHs快速检测方法，对其关键技术和方法进行系统研究，为土壤中PAHs快速评价提供新的检测视角和手段。项目从二维相关技术研究典型的8种PAHs在土壤中荧光特性入手，建立“特征荧光实验数据库”，确定激发光源-激光器；研究土壤理化参数对PAHs荧光影响的机理和规律，探究其与激光诱导荧光、可见/近红外漫反射光谱之间关系，建立减小土壤理化参数对PAHs测定影响的两级校正方法；基于激光诱导荧光对天津大港区土壤中PAHs进行检测，并与液相色谱分析结果对照，验证方法的有效性；探索土壤复杂程度、PAHs微量化和实验条件等因素对检出限的影响以及方法的适用性，并进行优化。该项目的研究为激光诱导荧光用于现场土壤PAHs污染程度的评价提供理论和实验基础。

目前土壤中多环芳烃（PAHs）检测方法，基本都依赖于实验室的取样检测，无法满足全面评价全国土壤污染状况的需求。本项目提出并建立了一种基于激光诱导荧光的土壤中PAHs快速检测方法，对其关键技术和方法进行系统研究，为土壤中PAHs快速评价提供新的检测视角和手段。研究了土壤中萘、蒽、苊、芘、荧蒽、苯并[a]芘、苯并[b]荧蒽和苯并[ghi]苝在溶液和土壤中的荧光特征，建立了“特征荧光实验数据库”，并研究了PAHs的激光诱导荧光特性；采用方差分析法，研究了土壤属性对PAHs荧光影响的程度，指出土壤粒径大小、含水率、土壤类型、有机质、含砂量及土壤颜色都对PAHs荧光强度生产显著影响；研究了土壤属性、土壤比表面积（SAA）和PAHs荧光强度之间的关系，指出：随着土壤粒径、含水率和含砂量的增大，SAA变小，而荧光强度变强，方差分析表明各因素都对SAA有显著影响，其中粒径最显著，且几个因素同时作用时，方差分析无统计意义，影响机理需进一步研究；基于二维相关谱技术研究了腐殖酸与PAHs之间的相互作用，建立了一种将腐殖酸荧光与PAHs荧光进行分离的异谱二维相关切谱方法；研究了土壤属性对近红外漫反射光谱和荧光光谱的影响规律，提出并建立一种组合光谱技术以减小土壤理化参数对PAHs荧光强度影响的校正方法，验证其有效性和普适性；提出并建立一种基于二维荧光相关谱土壤中PAHs检测方法，所建定量分析N-PLS模型的性能优于三维荧光谱；考虑到土壤属性的影响，分别建立组合光谱校正前后定量分析土壤中PAHs的N-PLS模型，并进行优化，提高了模型的预测的精度；采集大港油田附近不同深度石油污染土壤，研究了三维和激光诱导荧光特性，对其污染程度进行了定性评估；改进了实验室的LS-55荧光分光光度计，实现土壤中PAHs诱导荧光的激发。项目所取得的成果为激光诱导荧光用于现场土壤PAHs污染程度的评价提供理论和实验基础。