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The need for methodologies that allow for frequent and informative monitoring of dissolved organic matter (DOM) has become increasingly obvious due to the integral role of DOM in both natural and engineered systems. In response to this need, fluorescence spectroscopy, in combination with parallel factor analysis (PARAFAC), has shown great promise for monitoring DOM concentration and composition in a wide variety of settings. These methods involve exciting a water sample with a range of wavelengths of light and measuring the wavelengths and intensities at which the sample fluoresces. The DOM in the sample is then characterized based on the intensity, shape, and location of independent fluorescent components identified by PARAFAC. These components represent groups of fluorophores with similar fluorescent qualities.
The application of fluorescence spectroscopy with PARAFAC covers a wide range of systems and has allowed researchers to make inferences regarding the origins, mixing, production, and degradation of DOM. However, considerable uncertainty still remains regarding the relevance of an identified component due to a lack of discussion regarding the characteristics of similar components across studies. An investigation of the ubiquity of certain PARAFAC components and the consistently with which these components behave in different systems is needed.
The overall goal of this work is to evaluate PARAFAC results for a wide range of studies in order to better understand the chemistry of reoccurring fluorescent components. More specifically, comparisons of similar components across studies will be made regarding wavelength locations, characteristic ecosystems, physiochemical processes in the natural environment, and treatability in engineered systems. This synthesis is intended to describe the tendencies of reoccurring fluorescent components in a variety of settings such that PARAFAC users can be more confidently predict DOM composition and behavior based on identified components. |