Fluorescence Excitation-Emission Matrix Regional Integration to Quantify Spectra for Dissolved Organic Matter

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• 作者：Wen Chen ; Paul Westerhoff ; Jerry A. Leenheer ; and Karl Booksh
• 刊名：Environmental Science & Technology
• 出版年：2003
• 出版时间：December 15, 2003
• 年：2003
• 卷：37
• 期：24
• 页码：5701 - 5710
• 全文大小：417K
• 年卷期：v.37,no.24(December 15, 2003)
• ISSN：1520-5851

文摘

Excitation-emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolvedorganic matter (DOM) in water and soil. However, interpretingthe >10,000 wavelength-dependent fluorescence intensitydata points represented in EEMs has posed a significantchallenge. Fluorescence regional integration, a quantitativetechnique that integrates the volume beneath an EEM,was developed to analyze EEMs. EEMs were delineatedinto five excitation-emission regions based on fluorescenceof model compounds, DOM fractions, and marine watersor freshwaters. Volumetric integration under the EEM withineach region, normalized to the projected excitation-emission area within that region and dissolved organiccarbon concentration, resulted in a normalized region-specificEEM volume (ages/gifchars/Phi.gif" BORDER=0 >_i,n). Solid-state carbon nuclear magneticresonance (¹³C NMR), Fourier transform infrared (FTIR)analysis, ultraviolet-visible absorption spectra, and EEMswere obtained for standard Suwannee River fulvic acidand 15 hydrophobic or hydrophilic acid, neutral, and baseDOM fractions plus nonfractionated DOM from wastewatereffluents and rivers in the southwestern United States. DOMfractions fluoresced in one or more EEM regions. Thehighest cumulative EEM volume (ages/gifchars/Phi.gif" BORDER=0 >_T,n = ages/gifchars/Sigma.gif" BORDER=0 >ages/gifchars/Phi.gif" BORDER=0 >_i,n) was observedfor hydrophobic neutral DOM fractions, followed bylower ages/gifchars/Phi.gif" BORDER=0 >_T,n values for hydrophobic acid, base, and hydrophilicacid DOM fractions, respectively. An extracted wastewaterbiomass DOM sample contained aromatic protein- andhumic-like material and was characteristic of bacterial-soluble microbial products. Aromatic carbon and the presenceof specific aromatic compounds (as indicated by solid-state ¹³C NMR and FTIR data) resulted in EEMs that aidedin differentiating wastewater effluent DOM from drinkingwater DOM.