Dissolved organic carbon across Canadian lakes: Concentration and Optical properties
Dissolved organic carbon (DOC) is a key component of the biogeochemical functioning of lakes. Although we know much about the dynamics of DOC concentration and composition at the local and watershed scales, less is known about the variation of DOC at macroscales (i.e., continental) and how different in-lake and ecoregional properties at a continental scale interact to shape its concentration and composition. Here we present the initial results of the large-scale comparative study based on fluorescence spectroscopy to explore DOC optical properties from 680 lakes, part of the NSERC-funded Canadian LakePulse network, distributed within thirteen major ecozones across Canada, spanning a wide range of topographic, watershed, climate features and anthropogenic influence. Five fluorescence components were identified using parallel factor analysis (PARAFAC) and the intensity and relative abundance of these components were analyzed in relation to lake chemistry, catchment, and climate characteristics. There was a large degree of variability within and across ecoregions in lake DOC concentration, suggesting shifting geographic or climatic drivers of how much DOC is loaded and processed within lakes. Our preliminary results also indicate that ecoregions are clearly segregated into clusters on the basis of their respective PARAFAC components, confirming systematic differences in composition of DOC. Ecoregions with high human influence (e.g., the Prairies) in particular tend to have distinct DOC composition patterns.
Amir Reza Shahabinia, Jean-Francois Lapierre, Mathilde Couturier and Paul A. del Giorgio
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