氧化还原条件变化对上覆水体中溶解有机质的三维荧光光谱特征影响

利用三维荧光光谱(3EEMs)技术,考察了不同氧化还原条件对上覆水体中溶解有机质的三维荧光光谱特征的影响。好氧条件下上覆水体中DOM的荧光指数要高于厌氧条件,说明在不同的氧化还原条件下,上覆水体中DOM来源和组成均存在一定的差异性。上覆水体的三维荧光光谱特征也存在显著差异:好氧条件下,上覆水体中的类蛋白荧光峰强度均高于腐殖质类荧光峰强度,且三维荧光光谱图显示腐殖质类DOM存在氧化降解现象。厌氧条件下,上覆水体中腐殖质类荧光峰的强度随培养天数逐渐增加,当厌氧培养时间为21 d,C和D荧光峰的强度已分别上升至初始的3.51和3.78倍。在不同的氧化还原条件下,类蛋白和类腐殖质类DOM荧光峰位置和强度的变化,表明不同类型DOM的生物可利用性程度和在沉积物-水界面间迁移转化特征的差异性。

The influence of the redox conditions on the three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy of the dissolved organic matter (DOM) in the overlying water

In the present study three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy was applied to characterize the dissolved organic matter (DOM) in the overlying water under aerobic and anaerobic condition. The effects of redox condition were significant on 3DEEM fluorescence spectra of DOM, and in the aerobic condition, the peak intensities of protein-like fluorophores were both higher than those of the humic-like fluorophores, however, the phenomenon of the oxidative degradation of humic-original DOM could be seen. While in anaerobic condition, the peak intensities of the humic-like fluorescence were increased with increasing the incubation time. After the 21 day anaerobic incubation, the peak intensities of the humic-like fluorescence can be as 3.51 and 3.78 times higher than those of protein-like fluorescence. The differences in the DOM fluorescence parameters, e.g., peak intensities, locations and fluorescence index, indicate the difference in the chemical structures and various origins of the DOM in the overlying water between sediment-water interfaces.