光谱校正对溶解有机物三维荧光光谱特征影响

在三维荧光光谱(EEM)测定中，由仪器直接记录的光谱(称为未校正光谱)由于受荧光光度计光源灯或探测器等波长特性的影响，并不是荧光物质本身的真实光谱，研究了光谱校正对腐殖酸和色氨酸EEM光谱特征以及传统寻峰法和新兴FRI分析法结果的影响，结果表明：校正后，Ex/Em=220～450/250～500 nm范围内荧光强度降低，Em<250 nm范围内荧光强度增大，腐殖酸荧光峰明显“蓝移”。基于寻峰法的荧光指数(FI)和腐殖化指数(HIX)明显减小，自生源指数(BIX)略增;基于FRI分析法的反映各区域标准体积百分比P_{Ⅰ, n}，P_{Ⅱ, n}和P_{Ⅲ, n}明显上升，而P_{Ⅳ, n}和P_{Ⅴ, n}显著下降。因此，进行光谱校正是获得真实光谱谱图及光谱特征不可或缺的一部分。

Effect of Spectra Correction on the Fluorescence Characteristics of Dissolved Organic Matter

The Excitation-emission matrix (EEM) fluorescence spectra of dissolved organic matter (DOM) are not only dependent on the chemical structure of DOM as well as the local chemical environment around the DOM, but also dependent on the instrument employed for the analysis. Thus, in order to get the real spectra of the DOM, spectra correction of the effect of the instrument-specific response is necessary. However, some studies corrected DOM spectra, while still some studies didn’t, leading to inconformity when comparing the data and the results from different groups. The present work evaluated the effect of spectra correction on the fluorescence characteristics of DOM. The results demonstrated that DOM spectra differed significantly after correction. Fluorescence intensities showed a decrease in the range of Ex/Em=220~450/250~500 nm, while an increase at Em<250 nm after correction. Fluorescence intensity ratio (FI) and humification index (HIX) derived from peak picking method showed a decrease after correction, while biological index (BIX) increased slightly. P_Ⅰ,n, P_Ⅱ,n and P_Ⅲ,n derived from FRI analysis exhibited a significant increase, while P_Ⅳ,n and P_Ⅴ,n decreased. The results suggest that spectral correction should be included when analyzing the properties and trends of the DOM using EEM.