Fluorescence Spectroscopy Reveals Ubiquitous Presence of Oxidized and Reduced Quinones in Dissolved Organic Matter

详细信息    查看全文

• 作者：Rose M. Cory and Diane M. McKnight
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：November 1, 2005
• 年：2005
• 卷：39
• 期：21
• 页码：8142 - 8149
• 全文大小：485K
• 年卷期：v.39,no.21(November 1, 2005)
• ISSN：1520-5851

文摘

Excitation-emission matrixes (EEMs) of 379 dissolvedorganic matter (DOM) samples from diverse aquaticenvironments were modeled by parallel factor analysis(PARAFAC). Thirteen components likely representing groupsof similarly fluorescing moieties were found to explainthe variation in this data set. Seven of the thirteen componentswere identified as quinone-like based on comparison oftheir excitation and emission spectra to spectra of modelquinones. These quinone-like fluorophores were foundto vary in redox state and degree of conjugation. Twocomponents were identified as amino acid-like based oncomparison to tyrosine and tryptophan fluorescence spectra.The other four components are not yet associated withany class of molecules. The quinone-like fluorophores accountfor about 50% of the fluorescence for every sampleanalyzed, showing that quinone-like fluorophores are animportant and ubiquitous fluorescing moiety and in naturalwaters. Further, the distribution of the quinone-likefluorophores was evaluated as a function of environmentaland laboratory redox gradients. Under reducing conditions,the contribution of the reduced quinone-like fluorophoresincreased concurrent with a decrease in the oxidized quinone-like fluorophores, indicating that DOM fluorescence is afunction of redox state of quinone-like moieties. Lastly, aratio of two quinone-like fluorophores was found to explainthe variation in the fluorescence index. These resultsprovide new insight into the redox reactivity of DOM andhave implications for the application of fluorescencespectroscopy as a tool to characterize DOM.