From the peat bog to the estuarine mixing zone: Common features and variances in riverine dissolved organic matter determined by non-targeted analysis

It was shown that the three investigated samples share a significant proportion of the annotated molecular formulas though they vary in seawater content and origin, especially in the protein type region of the van Krevelen plot. Those compounds seem to be resistant to salting out or further degradation. Moreover, the lignin and tannin type region is largely overlapping in the Craggie Burn and the Suwannee River samples, but almost completely absent in the Halladale River sample. Therefore, our findings support the view that land-derived lignin and tannin structures can transport iron to the estuary, where they are degraded and ligand exchange takes place.