Eutrophication and geochemical factors affecting carbon accumulation in boreal lake sediments

Boreal lakes play a crucial role in global carbon cycling, acting as significant carbon sinks. However, human activities such as nutrient enrichment can disrupt these natural processes, impacting carbon sequestration. We investigated the relationship between sediment carbon accumulation and geochemical patterns across over 200 boreal lakes in Finland. We collected sediment cores from study lakes, dated them using cesium-137, and carried out multi-element analysis. In addition to sediment geochemistry, extensive water quality monitoring data were used to identify linkages between eutrophication and sediment carbon burial. Our analysis revealed that carbon mass accumulation rate (CMAR) was strongly linked to the mass accumulation rate (MAR), with high carbon burial observed in lakes with high MAR. Lakes influenced by nutrient enrichment (eutrophication) showed lower CMAR, particularly in systems with poor ecological status. We also identified positive relationships between potentially carbon-stabilizing elements (e.g. Ca, Cu) and CMAR. On the other hand, elements associated with agricultural influence or acidic soil leaching (e.g. K, Mn, Al) were linked with relatively low CMAR. Our results suggest that carbon accumulation in sediments is closely tied to nutrient dynamics and ecological health, with eutrophic lakes demonstrating reduced carbon storage capacity. This has broader relevance for climate change mitigation strategies, particularly in boreal regions where maintaining healthy aquatic ecosystems is critical for natural carbon sinks.

Presentation Preference: Poster

Primary Presenter: Eero Asmala, Geological Survey of Finland (eero.asmala@gtk.fi)

Authors:

Eero Asmala, Geological Survey of Finland  (eero.asmala@gtk.fi)

Tuomas Junna, Geological Survey of Finland  (tuomas.junna@gtk.fi)

Jari Mäkinen, Geological Survey of Finland  (jem.makinen@outlook.com)

Laura Härkönen, Finnish Environment Institute  (Laura.Harkonen@syke.fi)

Pirkko Kortelainen, Finnish Environment Institute  (pirkko.kortelainen@syke.fi)

Tom Jilbert, University of Helsinki  (tom.jilbert@helsinki.fi)

Karoliina Koho, Geological Survey of Finland  (karoliina.koho@gtk.fi)