The Arctic Ocean exports a large amount of terrestrial dissolved organic matter (DOM) to the Nordic seas. With climate change, the supply of terrestrial DOM from the Arctic Ocean will increase while less sea ice might lead to an increased loss of terrestrial DOM due to photodegradation. Here, we aimed to predict DOM photosensitivity based on fluorescence properties across the Eurasian Arctic. Exposures of seawater samples equa...

Freshwater from the Arctic participates in the globally important Atlantic Meridional Overturning Circulation (AMOC). We use high‐resolution, in situ observations of dissolved organic matter (DOM) fluorescence to trace the origins of freshwater and organic carbon in the densest component of the AMOC, namely Denmark Strait Overflow Water (DSOW). We find a distinct terrestrial DOM signal in DSOW and trace it upstream to the Sibe...

Some bacteria can degrade organic micropollutants (OMPs) as primary carbon sources. Due to typically low OMP concentrations, these bacteria may benefit from supplemental assimilation of natural substrates present in the pool of dissolved organic matter (DOM). The biodegradability of such auxiliary substrates and the impacts on OMP removal are tightly linked to biotransformation pathways. Here, we aimed to elucidate the biodegr...

The waters adjacent to the Nioghalvfjerdsbræ (79 North Glacier, 79NG) are influenced by Greenland Ice Sheet (GrIS) melt, sea-ice meltwater, and waters on the adjacent northeast Greenland shelf (NEGS). We investigated ocean acidification (OA) variables and the role of freshening, primary production, and air-sea CO 2 exchange in Dijmphna Sound (DS) and on the NEGS in the summers of 2012 and 2016. The upper 150 m consisted of Pol...

Many challenges remain before we can fully understand the multifaceted role that natural organic matter (NOM) plays in soil and aquatic systems. These challenges remain despite the considerable progress that has been made in understanding NOM’s properties and reactivity using the latest analytical techniques. For nearly 4 decades, the International Humic Substances Society (IHSS, which is a non-profit scientific society) has d...

Arctic waters are often enriched with terrestrial dissolved organic matter (DOM) characterized by having elevated visible wavelength fluorescence (commonly termed humic‐like). Here, we have identified the sources of fluorescent DOM (FDOM) in a high Arctic fjord (Young Sound, NE Greenland) influenced by glacial meltwater. The biological transformation of FDOM was further investigated using plankton community size‐fractionation...

The size‐dependent optical properties of dissolved organic matter (DOM) from four Swedish lakes were investigated using High Performance Size Exclusion Chromatography (HPSEC) in conjunction with online characterization of absorbance (240–600 nm) and fluorescence (excitation: 275 nm, emission: 300–600 nm). The molecular size of chromophoric DOM (CDOM) was consistently higher than that of fluorescent DOM (FDOM), with an average...

The Arctic Ocean receives a large amount of terrestrial dissolved organic matter (DOM) from rivers and more than half of this is removed during its passage through the Arctic Ocean. Terrestrial DOM is generally believed to have a low bioavailability and recent studies point to physicochemical processes such as sea ice formation as the source of the significant DOM removal in the Arctic Ocean. We present the results of a mesoco...

Inland waters transport large amounts of dissolved organic matter ( DOM ) from terrestrial environments to the oceans, but DOM also reacts en route, with substantial water column losses by mineralization and sedimentation. For DOM transformations along the aquatic continuum, lakes play an important role as they retain waters in the landscape allowing for more time to alter DOM . We know DOM losses are significant at the global...

Data from a long time series of temperature, salinity, and nutrient measurements in Disko Bay (West Greenland) reveal a marked change in the water characteristics during recent years. Seasonal dynamics in the upper 150 m of the water column were highly affected by the seasonality in meteorological conditions, while the deeper water strata were more stable and were primarily influenced by large‐scale circulation patterns. There...