Water-source characterization and classification with fluorescence EEM spectroscopy: PARAFAC analysis

Abstract

Water-quality protection and environmental forensics require rapid water monitoring and source identification. In this paper, parallel factor analysis (PARAFAC) of fluorescence excitation-emission matrix spectra (EEMS) was used to characterize and classify water samples from landfills, wastewater treatment plants, lakes, and rivers. The study showed that the optimal number of components was four to represent the data set. The fluorescence fingerprints for water samples from different sources were sufficiently different, so qualitative water classification could be achieved. Specifically, Component 1 was the major fluorescing centre in river waters, with characteristics consistent with humic-like fluorophores; Component 2 was the dominant fluorophore in the treated wastewaters; Component 3 was the characteristic fluorophore in landfill leachates; and Components 1, 3, and 4 existed in lake waters at comparable weight, among which Component 4 may be considered as a protein- or amino acid-like fluorophore.

Keywords:

• Fluorescence
• Excitation and emission spectrum
• EEMS
• PARAFAC analysis
• Water source classification

Acknowledgements

We thank Amod Koirala and Benjamin Teymouri at the University of Missouri for their assistance with sampling and EEMS analysis. Financial support from the Superfund program of Missouri Department of Natural Resources and Missouri Water Resources Research Center for this research is gratefully acknowledged. Constructive comments by three anonymous reviewers and Dr J. Albaiges on the paper are greatly appreciated.