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Contribution of sediment respiration to summer CO2 emission from low productive boreal and subarctic lakes
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
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2005 (English)In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 50, no 4, 529-535 p.Article in journal (Refereed) Published
Abstract [en]

We measured sediment production of carbon dioxide (CO2) and methane (CH4) and the net flux of CO2 across the surfaces of 15 boreal and subarctic lakes of different humic contents. Sediment respiration measurements were made in situ under ambient light conditions. The flux of CO2 between sediment and water varied between an uptake of 53 and an efflux of 182 mg C m−2 day−1 from the sediments. The mean respiration rate for sediments in contact with the upper mixed layer (SedR) was positively correlated to dissolved organic carbon (DOC) concentration in the water (r 2 = 0.61). The net flux of CO2 across the lake surface [net ecosystem exchange (NEE)] was also closely correlated to DOC concentration in the upper mixed layer (r 2 = 0.73). The respiration in the water column was generally 10-fold higher per unit lake area compared to sediment respiration. Lakes with DOC concentrations <5.6 mg L−1 had net consumption of CO2 in the sediments, which we ascribe to benthic primary production. Only lakes with very low DOC concentrations were net autotrophic (<2.6 mg L−1) due to the dominance of dissolved allochthonous organic carbon in the water as an energy source for aquatic organisms. In addition to previous findings of allochthonous organic matter as an important driver of heterotrophic metabolism in the water column of lakes, this study suggests that sediment metabolism is also highly dependent on allochthonous carbon sources.

Place, publisher, year, edition, pages
2005. Vol. 50, no 4, 529-535 p.
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-93435DOI: 10.1007/s00248-005-5007-xOAI: oai:DiVA.org:uu-93435DiVA: diva2:166908
Available from: 2005-09-21 Created: 2005-09-21 Last updated: 2013-05-15Bibliographically approved
In thesis
1. Carbon Dioxide Supersaturation in Lakes – Causes, Consequences and Sensitivity to Climate Change
Open this publication in new window or tab >>Carbon Dioxide Supersaturation in Lakes – Causes, Consequences and Sensitivity to Climate Change
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The global carbon cycle is intimately linked with the earth’s climate system. Knowledge about carbon cycling in the biosphere is therefore crucial for predictions of climate change. This thesis investigates the carbon dioxide balance of Swedish boreal lakes, its regulation, significance to the carbon budget of the boreal landscape, and sensitivity to climate change.

Swedish boreal lakes were almost exclusively supersaturated in CO2 with respect to the atmosphere, resulting in an emission of CO2 from lakes to the atmosphere. Lake pCO2 was closely related to the concentration of terrigenous dissolved organic carbon (DOC), indicating that the utilization of terrigenous DOC by lake bacteria is a major source of CO2. This conclusion is supported by independent field studies, showing that net plankton respiration accounts for most of the CO2 emitted from Swedish boreal lakes, while photochemical mineralization and sediment respiration were less important.

Mineralization of terrigenous DOC and subsequent emission of CO2 from lakes to the atmosphere was a major carbon loss factor in 21 major Swedish boreal catchments, removing 30-80% of the organic carbon exported from terrestrial soils to surface waters. Lake CO2 emission is in the same order of magnitude as organic carbon accumulation in boreal forest soils, and should therefore be included in the carbon budget of the boreal landscape.

In a set of nearly 5000 global lakes, DOC concentration was a much more important regulator of lake pCO2 than temperature. Climate change will therefore affect the carbon balance of lakes primarily via alterations in terrestrial DOC export, rather than via changes in temperature per se. Both current observations and models of future climate suggest an increasing export of terrigenous DOC from many Scandinavian catchments. Hence, there probably is a current trend towards higher CO2 emission from Swedish boreal lakes, which is likely to continue in the future.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2005. 42 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 90
Biology, carbon dioxide, boreal lakes, respiration, dissolved organic carbon, climate change, Biologi
National Category
Biological Sciences
urn:nbn:se:uu:diva-5920 (URN)91-554-6329-0 (ISBN)
Public defence
2005-10-14, Ekmansalen, Kärnhuset, EBC, Norbyvägen 14, Uppsala, 10:00 (English)
Available from: 2005-09-21 Created: 2005-09-21 Last updated: 2009-03-30Bibliographically approved

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