The melting of the Greenland Ice Sheet (GrIS) due to climate heating results in increasing export of dissolved organic matter (DOM) in glacial meltwaters. However, little is known about how the source and composition of exported DOM, which is key for understanding its fate in downstream ecosystems.

A new paper has been published in Journal of Geophysical Research-BIogeosciences, lead by our colleague Anne Kellerman from Florida State University and co-authored by Tyler and Marek, showing the results of DOM analysis of samples collected over the 2015 ablation season at Leverett Glacier, a large land‐terminating glacier of the GrIS. The results suggest terrestrial inputs from overridden soils dominated DOM early season inputs before progressive dilution with increasing discharge. Later on, during the so-called ‘outburst’ period, supraglacial (surface meltwater) drainage events disrupted the subglacial drainage system and introduced dominant protein‐like signatures not observed in basal flow. This indicates that subglacial hydrology and changing water sources influence exported DOC concentration and DOM composition. The observed changes likely reflect seasonal variations in the impact of glacial inputs on secondary production in downstream ecosystems due to shifting hydrologic regimes.

Kellerman AM, Hawkings JR, Wadham JL, Kohler TJ, Stibal M, Grater E, Marshall M, Hatton JE, Beaton A, Spencer RGM (2020) Glacier outflow dissolved organic matter as a window into seasonally changing carbon sources: Leverett Glacier, Greenland. Journal of Geophysical Research: Biogeosciences125:e2019JG005161 doi: 10.1029/2019JG005161