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Regional Variability and Drivers of Below Ice CO2 in Boreal and Subarctic Lakes
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
Finnish Environment Institute.
Department of Environmental Sciences, University of Helsinki.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
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2016 (English)In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 19, no 3, 461-476 p.Article in journal (Refereed) Published
Abstract [en]

Northern lakes are ice-covered for considerable portions of the year, where carbon dioxide (CO2) can accumulate below ice, subsequently leading to high CO2 emissions at ice-melt. Current knowledge on the regional control and variability of below ice partial pressure of carbon dioxide (pCO(2)) is lacking, creating a gap in our understanding of how ice cover dynamics affect the CO2 accumulation below ice and therefore CO2 emissions from inland waters during the ice-melt period. To narrow this gap, we identified the drivers of below ice pCO(2) variation across 506 Swedish and Finnish lakes using water chemistry, lake morphometry, catchment characteristics, lake position, and climate variables. We found that lake depth and trophic status were the most important variables explaining variations in below ice pCO(2) across the 506 lakes(.) Together, lake morphometry and water chemistry explained 53% of the site-to-site variation in below ice pCO(2). Regional climate (including ice cover duration) and latitude only explained 7% of the variation in below ice pCO(2). Thus, our results suggest that on a regional scale a shortening of the ice cover period on lakes may not directly affect the accumulation of CO2 below ice but rather indirectly through increased mobility of nutrients and carbon loading to lakes. Thus, given that climate-induced changes are most evident in northern ecosystems, adequately predicting the consequences of a changing climate on future CO2 emission estimates from northern lakes involves monitoring changes not only to ice cover but also to changes in the trophic status of lakes.

Place, publisher, year, edition, pages
2016. Vol. 19, no 3, 461-476 p.
Keyword [en]
CO2; winter limnology; ice cover; carbon; nutrients; lake depth
National Category
URN: urn:nbn:se:uu:diva-275017DOI: 10.1007/s10021-015-9944-zISI: 000373018200007OAI: oai:DiVA.org:uu-275017DiVA: diva2:898339
Swedish Research CouncilSwedish Research Council FormasEU, European Research Council
Available from: 2016-01-27 Created: 2016-01-27 Last updated: 2016-08-09Bibliographically approved
In thesis
1. Greenhouse Gas Dynamics in Ice-covered Lakes Across Spatial and Temporal Scales
Open this publication in new window or tab >>Greenhouse Gas Dynamics in Ice-covered Lakes Across Spatial and Temporal Scales
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Lakes play a major role in the global carbon (C) cycle, despite making up a small area of earth’s surface. Lakes receive, transport and process sizable amounts of C, emitting a substantial amount of the greenhouse gases, carbon dioxide (CO2) and methane (CH4), into the atmosphere. Ice-covered lakes are particularly sensitive to climate change, as future reductions to the duration of lake ice cover will have profound effects on the biogeochemical cycling of C in lakes. It is still largely unknown how reduced ice cover duration will affect CO2 and CH4 emissions from ice-covered lakes. Thus, the primary aim of this thesis was to fill this knowledge gap by monitoring the spatial and temporal dynamics of CO2 and CH4 in ice-covered lakes. The results of this thesis demonstrate that below ice CO2 and CH4 were spatially and temporally variable. Nutrients were strongly linked to below ice CO2 and CH4 oxidation variations across lakes. In addition, below ice CO2 was generally highest in small shallow lakes, and in bottom waters. Whilst below ice CH4 was elevated in surface waters near where bubbles from anoxic lake sediment were trapped. During the ice-cover period, CO2 accumulation below ice was not linear, and at ice-melt incomplete mixing of lake waters resulted in a continued CO2 storage in bottom waters. Further, CO2 transported from the catchment and bottom waters contributed to high CO2 emissions. The collective findings of this thesis indicate that CO2 and CH4 emissions from ice-covered lakes will likely increase in the future. The strong relationship between nutrients and C processes below ice, imply that future changes to nutrient fluxes within lakes will influence the biogeochemical cycling of C in lakes. Since catchment and lake sediment C fluxes play a considerable role in below ice CO2 and CH4 dynamics, changes to hydrology and thermal stability of lakes will undoubtedly alter CO2 and CH4 emissions. Nevertheless, ice-covered lakes constitute a significant component of the global C cycle, and as such, should be carefully monitored and accounted for when addressing the impacts of global climate change.  

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 53 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1341
carbon cycle, climate change, cryosphere, carbon dioxide, methane, lakes, winter limnology, methane oxidation, nutrients, catchment
National Category
Natural Sciences
Research subject
urn:nbn:se:uu:diva-275018 (URN)978-91-554-9467-4 (ISBN)
Public defence
2016-03-18, Friessalen, Evolutionary Biology Centre (EBC), Norbyvägen 14, Uppsala, 13:15 (English)
Available from: 2016-02-26 Created: 2016-01-28 Last updated: 2016-03-09

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