Fluorescence components of natural dissolved organic matter (DOM) from aquatic systems of an Andean Patagonian catchment: Applying different data restriction criteria for PARAFAC modelling

GARCÍA, P.E.; GARCÍA, R.D.; SOTO CÁRDENAS, C.; GEREA, M.; REISSIG, M.; PÉREZ, G.L.; DE STEFANO, L.G.; GIANELLO, D.; QUEIMALIÑOS, C.; DIÉGUEZ, M.C.

SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY.

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2020 vol. 229 p. 1 - 7

1386-1425

Fluorescence spectroscopy is a widely applied technique to characterize the composition of the fluorescent fraction of dissolved organic matter (DOM), allowing to infer sources and diagenetic state of soil, marine and freshwater DOM samples. The analysis of fluorescent DOM (FDOM) is often carried out by multi-way models such asparallel factor analysis (PARAFAC), which allows decomposing excitation-emission matrices (EEMs) obtainedfrom DOM samples into their underlying chemical components. Some aspects of the performance/accuracy ofthe EEM-PARAFAC technique regarding the use of selective vs. non-selective EEM data are still in discussion. Inthis investigation, we evaluated the outcome of two different approaches (non-selective and selective) appliedto study the composition of DOM from four headwater streams (Case 1) and from two neighboring shallowlakes (Case 2), all belonging to the same Andean watershed within Nahuel Huapi National Park in North Patagonia (Argentina). In both cases, the outcome of the PARAFAC performed to non-selective data (EEM datasets fromall the streams and the two lakes) vs. selective datasets (EEMs from each stream and each lake treated separately)is compared on the basis of modelled fluorescent components. Regardless of the restriction criteria applied forthe analyses, the results obtained indicated similar component loadings in the four streams and in the twolakes. The similarity of the outcomes likely relates to the low internal variation of the EEMs, since these are located in the same catchment, influenced by similar soils and vegetation which are the main DOM sources. Therefore, we conclude that the use of a small selective EEM dataset may not condition the validation of the FDOMcomponents and their temporal dynamics.