Research project Can increased delivery of iron from thawing permafrost enhance the magnitude and stability of the carbon sink in Arctic lakes?
Enhanced fluxes of terrestrial organic C and iron are turning clear Arctic waters orange, causing a visible ecosystem transformation of aquatic systems known as ‘rusting’. This could enhance the potential of Arctic lakes as C sinks because interactions between organic C and reactive minerals such as iron oxides promote long-term C storage in soils and sediments. The central aim of this project is to determine the importance of organo-mineral interactions in shaping the quantity and stability of the Arctic lake C sink.
Vrije Universiteit Amsterdam (Prof. J Vonk)
Leeds University (Prof. C Peacock)
Shanghai Jiao Tong University (Prof. X Cui)
Lakes are hotspots of carbon (C) cycling and collectively represent a globally significant C sink that is comparable in magnitude to that of the oceans. Despite this, the mechanisms that preserve C in lake sediments remain poorly understood. Over 65% of global lakes are at high latitudes where amplified warming and ongoing permafrost degradation mobilize large quantities of both organic and mineral material into inland waters, with the potential to fundamentally alter lake C dynamics. In particular, enhanced fluxes of terrestrial organic C and iron are turning clear Arctic waters orange, causing a visible ecosystem transformation of aquatic systems known as ‘rusting’. This could enhance the potential of Arctic lakes as C sinks because interactions between organic C and reactive minerals such as iron oxides promote long-term C storage in soils and marine sediments. However, the role of these organo-mineral interactions has been neglected in freshwater sediments. As permafrost thaw delivers the key ingredients for such interactions and ‘rusting’ becomes more widespread, the investigation of their influence on C preservation in Arctic lake sediments becomes increasingly timely and relevant.
The central aim of this project is to determine the importance of organo-mineral interactions in shaping the quantity and stability of the Arctic lake C sink. To assess the effect on C storage, I will quantify pools of mineral-associated C fractions in sediment cores from 30 lakes that have experienced different degrees of ‘rusting’ across Greenland and Arctic Scandinavia. Focusing on a range of lakes that systematically vary in their organic C to iron ratios and deep-water oxygen conditions, two factors that determine the potential for organo-mineral interactions, this project is designed to uncover controls on lake sediment C storage and stability.
To characterize how organo-mineral interactions affect the stability of stored C, I will use advanced techniques that include ramped pyrolysis-oxidation coupled with radiocarbon measurements, molecular fingerprinting, and incubations that together reveal physical, chemical, and microbial aspects of sediment C reactivity. This project will provide new insights into factors that determine the C sink potential of Arctic lakes and more generally into our understanding of the role of organo-mineral interactions in C preservation.
