Abstract

Parallel factor analysis (PARAFAC) has facilitated an explosion in research connecting the fluorescence properties of dissolved organic matter (DOM) to its functions and biogeochemical cycling in natural and engineered systems. However, the validation of robust PARAFAC models using split-half analysis requires an oft unrealistically large number (hundreds to thousands) of excitation–emission matrices (EEMs), and models with too few components may not adequately describe differences between DOM. This study used self-organizing maps (SOM) and comparing changes in residuals with the effects of adding components to estimate the number of PARAFAC components in DOM from two data sets: MS (110 EEMs from nine leaf leachates and headwaters) and LR (64 EEMs from the Lena River). Clustering by SOM demonstrated that peaks clearly persisted in model residuals after validation by split-half analysis. Plotting the changes to residuals was an effective method for visualizing the removal of fluorophore-like fluorescence caused by increasing the number of PARAFAC components. Extracting additional PARAFAC components via residuals analysis increased the proportion of correctly identified size-fractionated leaf leachates from 56.0 ± 0.8 to 75.2 ± 0.9%, and from 51.7 ± 1.4 to 92.9 ± 0.0% for whole leachates. Model overfitting was assessed by considering the correlations between components, and their distributions amongst samples. Advanced residuals analysis improved the ability of PARAFAC to resolve the variation in DOM fluorescence, and presents an enhanced validation approach for assessing the number of components that can be used to supplement the potentially misleading results of split-half analysis.

© 2016 The Author(s)

Dissolved organic matter in bovine slaughterhouse wastewater using fluorescence spectroscopy associated with CP/PARAFAC and PCA methods

Murillo Cruz Matos, Amanda Maria Tadini, Fernando Rodrigues da Conceição, Amilcar Machulek Junior, Carlos Renato Menegatti, Stéphane Mounier, Anderson Rodrigues Lima Caires, and Gustavo Nicolodelli
Appl. Opt. 61(22) 6590-6598 (2022)

Determination of the absorption coefficient of chromophoric dissolved organic matter from underway spectrophotometry

Giorgio Dall’Olmo, Robert J. W. Brewin, Francesco Nencioli, Emanuele Organelli, Ina Lefering, David McKee, Rüdiger Röttgers, Catherine Mitchell, Emmanuel Boss, Annick Bricaud, and Gavin Tilstone
Opt. Express 25(24) A1079-A1095 (2017)

Design and daytime performance of laser-induced fluorescence spectrum lidar for simultaneous detection of multiple components, dissolved organic matter, phycocyanin, and chlorophyll in river water

Yasunori Saito, Kei Kakuda, Mizuho Yokoyama, Tomoki Kubota, Takayuki Tomida, and Ho-Dong Park
Appl. Opt. 55(24) 6727-6734 (2016)

Assessment of the colored dissolved organic matter in coastal waters from ocean color remote sensing.

Hubert Loisel, Vincent Vantrepotte, David Dessailly, and Xavier Mériaux
Opt. Express 22(11) 13109-13124 (2014)

Beam attenuation coefficient retrieval by inversion of airborne lidar-induced chromophoric dissolved organic matter fluorescence. I. Theory

Frank E. Hoge
Appl. Opt. 45(10) 2344-2351 (2006)