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Contribution of sediment respiration to summer CO2 emission from boreal and subarctic lakes
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
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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 (CO(2)) and methane (CH(4)) and the net flux of CO(2) 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 CO(2) 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 CO(2) 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 CO(2) 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.
URN: urn:nbn:se:umu:diva-4406DOI: 10.1007/s00248-005-5007-xOAI: diva2:143493
Available from: 2005-02-17 Created: 2005-02-17 Last updated: 2010-11-10Bibliographically approved
In thesis
1. Regulation of carbon dioxide emission from Swedish boreal lakes and the Gulf of Bothnia
Open this publication in new window or tab >>Regulation of carbon dioxide emission from Swedish boreal lakes and the Gulf of Bothnia
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The global carbon cycle is subject to intense research, where sources and sinks for greenhouse gases, carbon dioxide in particular, are estimated for various systems and biomes. Lakes have previously been neglected in carbon balance estimations, but have recently been recognized to be significant net sources of CO2.

This thesis estimates emission of carbon dioxide (CO2) from boreal lakes and factors regulating the CO2 saturation from field measurements of CO2 concentration along with a number of chemical, biological and physical parameters. Concentration of dissolved organic carbon (DOC) was found to be the most important factor for CO2 saturation in lake water, whereas climatic parameters such as precipitation, temperature and global radiation were less influential. All lakes were supersaturated with and, thus, sources of CO2. Sediment incubation experiments indicated that in-lake mineralization processes during summer stratification mainly occurred in the pelagial. Approximately 10% of the CO2 emitted from the lake surface was produced in epilimnetic sediments.

The mineralization of DOC and emission of CO2 from freshwaters was calculated on a catchment basis for almost 80,000 lakes and 21 major catchments in Sweden, together with rates of sedimentation in lakes and export of organic carbon to the sea. The total export of terrestrial organic carbon to freshwaters could thereby be estimated and consequently also the importance of lakes for the withdrawal of organic carbon export from terrestrial sources to the sea. Lakes removed 30-80% of imported terrestrial organic carbon, and mineralization and CO2 emission were much more important than sedimentation of carbon. The carbon loss was closely related to water retention time, where catchments with short residence times (<1 year) had low carbon retentions, whereas in catchments with long residence times (>3 years) a majority of the imported TOC was removed in the lake systems.

The Gulf of Bothnia was also studied in this thesis and found to be a net heterotrophic system, emitting large amounts of CO2 to the atmosphere on an annual basis. The rate of CO2 emission was depending on the balance between primary production and bacterial respiration, and the system was oscillating between being a source and a sink of CO2.

Place, publisher, year, edition, pages
Umeå universitet, 2005. 24 p.
Physical geography and sedimentology, lakes, boreal, Gulf of bothnia, CO2, NEE, DOC, mineralization, sediment, catchment, net heterotrophy, Naturgeografi och sedimentologi
National Category
Physical Geography
Research subject
Physical Geography
urn:nbn:se:umu:diva-453 (URN)91-7305-818-1 (ISBN)
Public defence
2005-03-11, KB3B1, KBC-huset, Umeå universitet, Umeå, 10:00
Available from: 2005-02-17 Created: 2005-02-17 Last updated: 2011-03-21Bibliographically approved

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Bergström, Ann-KristinJonsson, AndersJansson, Mats
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Ecology and Environmental ScienceDepartment of Ecology and Environmental Sciences
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