In a new paper published in Global Biogeochemical Cycles and led by Petra Vinšová, we reveal the biogeochemical legacy of subglacial sediments exposed by retreating Arctic glaciers.

We collected freshly thawed sediments of subglacial origin and investigated them comprehensively, using radiocarbon dating, organic matter (OM) biomarker analysis, nutrient content determination (including fractions of phosphorus), and microbial community structure analysis. Our samples were collected at the margins of a number of glaciers in Norway, Iceland, Svalbard, Greenland, and Alaska, presenting a unique circumpolar sample set. The results were then placed in the context of local geological settings and glaciation histories.

We show the character of the sediments is mostly determined by local glaciation history and bedrock lithology. Most subglacial sediments offer high amounts of readily bioavailable phosphorus but lack readily accessible carbon substrates. The subglacial OM originated mainly from overridden terrestrial vascular plants. The results of OM biomarker analysis and ¹⁴C dating suggest the OM substrates degrade in the subglacial environment and are reworked by the resident microbial communities.

Our findings shed more light onto the origin of subglacial OM and its transformation in the subglacial environment, and point out that the biogeochemical characteristics of subglacial sediments is an important factor for the early development of the expanding proglacial areas in the Arctic.

Vinšová P, Kohler TJ, Simpson MJ, Hajdas I, Yde JC, Falteisek L, Žárský JD, Yuan T, Tejnecký V, Mercl F, Hood E, Stibal M (2022) The biogeochemical legacy of Arctic subglacial sediments exposed by glacier retreat. Global Biogeochemical Cycles 36:e2021GB007126 doi: 10.1029/2021GB007126