EEMs and PARAFAC in North Patagonia (Argentina): adapting to a methodology in continuous progress

GARCÍA, PATRICIA E.; GARCIA, DANIEL; SOTO CÁRDENAS, CAROLINA; GEREA, MARINA; REISSIG, MARIANA; PÉREZ, GONZALO; DIEGUEZ, MARÍA DEL CARMEN; CLAUDIA, QUEIMALIÑOS

Carqueiranne

Workshop; WOMS 2018; 2018

The study of the fluorescent dissolved organic matter in Northwestern Patagonia through excitation emission matrices (EEMs) by our research groupstarted in 2012. The first paper that we published using EEMs included sixmountain lakes. The peak picking method was used due to the low numberof EEMs collected, and three peaks were identified (Peak C, Peak A and Peak T)(García, P. et al., 2015a) (Figure 1). In this study, we deal not onlywith the low number of EEMs to perform PARAFAC analyses, but also lowfluorescence was found in some samples. The next research deals with theterrestrial inputs of DOM in four headstreams in North Patagonia (García, R. etal., 2015b). In this opportunity, we were able to perform PARAFAC on 120EEMs and a three-component model was validated through slit-half and randominitialization (Figure 2). Two components were humic-like: C1 (peak A+ peak M)and C2 (peak A + peak C), and one was protein-like: C3 (peak T). This studyhighlighted the used of PARAFAC in order to identify underlying components suchas C1 (A+M), that were not taken in consideration in the previous study. Wecollected 44 EEMs and, similar to previous findings, three-component model wasvalidated: C1 (A+M), C2 (A+C) and C3 (T). At this point, we were almost convincedthat only a three-component model could be achieved in the aquatic systems inour region. In order to identify different sources of DOM for a small catchmentarea, our research group performed experiments using DOM leached from soil andleaf litter. At this time, PARAFAC validated a four-component model (Figure 3)(García, R. et al., 2018). The first three components were previouslyfound in different lakes and streams from the area, while C4 showed up as a newcomponent. The C4 was composed of humic substances and resembles a"shifted" peak M. This component prevailed only in samples of leaflecheates, reason why it was called Mleaf