Hydrologic Compartments are More Important than Ecozone in Size-Based Characterization of Freshwater Dissolved Organic Matter across Canada
Dissolved Organic Matter (DOM) represents a mixture of organic molecules that vary due to different source materials and degree of processing. Characterizing how DOM composition evolves along the aquatic continuum can be difficult. Using a size-exclusion chromatography technique (LC-OCD), we assessed the variability in DOM composition from both surface and groundwaters across a number of Canadian ecozones (mean annual temperature spanning -10 to +6 C). A wide range in DOM concentration was found from 0.2 to 120 mg C/L. Proportions of different size-based groupings across ecozones were variable, yet similarities between specific water-body types, regardless of location, suggest commonality in the processes dictating DOM composition. A PCA identified 70% of the variation in LC-OCD derived DOM compositions could be explained by the water-body type. We find that DOM composition within a specific water-body type is similar regardless of the differences in climate or surrounding vegetation where the sample originated from. HighlightsO_LISize-exclusion chromatography (using LC-OCD) is a fast and effective tool to quantify differences in DOM composition across different environments C_LIO_LIProportions of biopolymers and low molecular weight fractions can distinguish between surface and groundwater DOM C_LIO_LISimilar water-body types have comparable DOM size compositions across ecozones that range in annual air temperatures from -10 to 6{o}C C_LI