Dissolved organic matter degradation in the freshwater portion of the St. Lawrence River (2019)

During the summer of 2019, we sampled a 207 km transect of the St. Lawrence, a large temperate river in which flows two strikingly distinct water masses in terms of origin as well as chemical and physical properties. We then assessed dissolved organic matter bio- and photo-reactivity at 40 sites along the river through a series of standardized incubations and exposure to simulated sunlight, and then used water irradiance and morphometric profiles to estimate in situ areal rates of processing across the river. The main variables presented are DOC concentrations and DOM composition data generated by a PARAFAC model. In addition, this dataset also includes results for a suite of standard physical and chemical variables as well as light attenuation profiles obtained with a profiling radiometer.