Carbon burial (in)efficiency in northern lakes: in situ molecular insights on sediment carbon burial and loss

Northern lakes are an important carbon sink, with organic carbon (OC) accumulation rates equal in importance to forest soils and peatlands.

In response to ongoing environmental and climate changes, OC burial rates in sediments have increased ~2–3 fold over the past 100-years, and the ability to sequester more OC would be important in future climate scenarios.

However, we hypothesize the magnitude of this recent increase in burial is grossly overestimated because of the failure to account for post-depositional mineralization in the sediment.

In previous research our group has shown ≥25% of the OC, particularly fresher aquatic organic matter (OM) sources, was lost during the first ~30-years of burial (12 cm depth).

In most northern lakes, this depth where OC is still being mineralized this would encompass 100–200-years of OC accumulation.

Consequently, much of the estimated increase in OC burial rates may be a temporary feature rather than representing a true increase in C sequestration.To develop a more realistic model of the role of northern lakes as OC sinks in the global C cycle under a changing climate, we will pair a unique high-resolution study with a multi-lake analysis to assess OC burial processes with regard to, e.g., differences in source OM composition, landscape characteristics, and seasonal to millennial responses to environmental and climate changes.