6 - Excitation-emission fluorescence mapping and multiway techniques for profiling natural organic matter

Abstract

In aquatic ecosystems, dissolved organic matter (DOM) plays a crucial role in carbon cycling on a global scale. The excitation-emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize DOM water, including the traditional “peak-picking” method, EEM coupled with parallel factor analysis (EEM-PARAFAC), and EEM coupled with fluorescence regional integration (EEM-FRI). The traditional peak-picking method makes it difficult to assess the fluorescent DOM (FDOM) dynamics in waters due to the unreliability of fluorescence peaks. EEM-PARAFAC can decompose EEM spectra of DOM into individual fluorescent components to investigate the correlations between the fluorescent components and water quality parameters. However, the EEM-PARAFAC technique can provide only several paired fluorescence intensity data with limited FDOM components information. Compared to the EEM-PARAFAC method, EEM-FRI has been proven to be an effective method to integrate the volumes beneath defined EEM regions, where the integrated fluorescence intensities represent the FDOM components. EEM can be thus separated into different regions by FRI, which are further related to different FDOM components. The potential of EEM-FRI to assess DOM dynamics will be discussed in this chapter.