LAC project

The Lakes in the Arctic Carbon Cycle (LAC) project.

It is well known that the Arctic is warming rapidly, with this warming believed to be contributing to an expansion of vegetation in a northerly direction. Arctic ‘greening’ has been observed in Alaska and tree expansion northwards is predicted to reach the coast of European Russia by 2100.

When new shrub or tree species grow, the nutrients that are released from the soil to lakes are expected to change. However, the precise changes are debated in the science community. These relationships between climate, vegetation and lakes may cause carbon storage or carbon release depending on lake biology and regional geography.

The Arctic is particularly sensitive to climate change and the vast stores of carbon in high latitude soils make this research especially important. Additional COrelease to the atmosphere could speed up ice sheet melting and sea level rise.

Map of the arctic_mark

Above: Three field sites where sediment cores will be taken.

This study will extract sediment cores from fieldwork sites across the Arctic with international collaborators including south-west Greenland at Sisimiut, European Russia (Komi Science Centre) and Alaska (National Park Service/South Central Brooks Range). Three teams will coordinate the fieldwork in the regional sites and then sediments from all cores will be shared between Nottingham, Loughbrough, University College London and Southampton universities for detailed ‘proxy’ analysis.

Sediment cores from lakes are excellent archives of environmental change, and so by studying past responses to climate change, over a geological time period known as the Holocene (~12,000 to present) we will be able to understand how carbon storage or release might be affected.

Key questions we aim to research…

•Have Arctic lakes been carbon sources or sinks in the last 10,000 years?
•How does plant functional type (PFT) composition affect dissolved organic carbon (DOC) export?
•How does dissolved organic carbon (DOC) determine lake metabolic state ?
•To what extent are lake carbon dynamics a function of lake biological structure (e.g. trophic interactions, biodiversity)
•How do changing PFTs influence lake carbon and nitrogen processing, and aquatic production, and biodiversity?
Methods

Above: Conceptual diagram of sampling strategy

 

Regional replication

All lake sediments will be shared between laboratories in Nottingham, Loughborough, UCL and Southampton universities for specialist analysis. Taking regionally replicated samples will help us to increase our confidence of changes within regions, while repeating the study in different areas of the arctic will enable the study to compare the differences between regional response to past climate change.

Methods include:

Pigment analysis (using High-Performance Liquid Chromatography, HPLC)

Loss-on-ignition

C/N isotopes

Macrofossils

Water chemistry

Chironomid analysis

Cladocera analysis

Pollen analysis

Diatom analysis

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