Excitation–emission fluorescence matrix to study pH influence on organic matter fluorescence in the Amazon basin rivers

Study of the pH influence on the optical properties of dissolved organic matter using fluorescence excitation–emission matrix and parallel factor analysis

“…Not only the fluorescence intensities of the same peak in SRFA and NRNOM but also the three peaks in either sample presented different trends with changes in the pH change. This result indicates that the chemical behavior of the fluorophores in SRFA and NRNOM must be somewhat different [23], and it needs to be further studied.…”

“…Although the EEM spectroscopic approach has a greater density of spectral information than the traditional fluorescence approaches, it can demonstrate that quenching (or enhancement) of fluorescence intensity by proton and metal ions is quantitatively dissimilar in different regions of the fluorescence landscape [2,[17][18][19][20][21]. The EEM landscape has been typically characterized by noting the locations of one or more peaks that correspond to the maximum fluorescence intensities ("peak picking") [22][23][24]. Due to the broad nature and the lack of fine structure of the organic matter fluorescence spectra, the visual "peak picking" process is subjective in nature and may lead to erroneous conclusions because peaks commonly reflect more than one underlying fluorophore.…”

“…Because the functionality of DOM, such as carboxylic, phenolic, alcoholic, enolic hydroxyl, carbonyl and nitrogen-, S-and Pcontaining functional groups, is very sensitive to pH, and the hydrolysis process of the functionalities may affect their fluorescence intensity [23]. In this paper, the optical properties of DOM were examined by investigating the influence of pH using fluorescence excitation-emission matrix and parallel factor analysis; the results of this study will provide some important information of the properties of DOM for further understanding its interaction with metals in future studies.…”

Technical Note: Comparison of storage strategies of sea surface microlayer samples

“…However, CDOM absorption has been observed to increase with increasing pH (Andersen et al, 2000) and acidification is also reported to change fluorescence intensities and to introduce spectral shifts. For example, Patel-Sorrentino et al (2002) observed an increase in fluorescence intensity with increasing pH between 1 to 10-11 and a decrease at pH 12; Mobed et al (1996) found a red shift in florescence intensity maxima with increasing pH in soil-derived humics. The same study also reported a blue shift with increasing pH in aquatic derived DOM.…”

Study of influencing factors to chromophoric dissolved organic matter absorption properties from fluorescence features in Taihu lake in autumn

“…Three-dimensional fluorescence spectroscopy (3DEEM) is a popular method in the component identification of CDOM and algae for its high sensitivity and small interference (Mobed et al, 1996;McKnight et al, 2001;Patel-Sorrentino et al, 2002;Leenheer and Croué, 2003;Murphy et al, 2008). With the development of fluorescence sensor, fluorescence-to-absorption algorithms to retrieve CDOM absorption became more and more significative.…”