Characterization of dissolved organic matter in Lake Superior and its watershed using ultrahigh resolution mass spectrometry

► ESI FT-ICR-MS was applied to DOM extracts from Lake Superior and its watershed. ► Chemical similarity was related to hydrological proximity and flow conditions. ► Lake Superior DOM was distinguished by lignin-like and reduced hydrocarbon formulae. ► Lake Superior DOM had a higher proportion of formulae containing nitrogen or sulfur. ► There was a conserved portion of formulae across the watershed's DOM samples.