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The catchment and climate regulation of pCO2 in boreal 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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2003 (English)In: Global Change Biology, Vol. 9, no 4, 630-641 p.Article in journal (Refereed) Published
Abstract [en]

The regulation of surface water pCO2 was studied in a set of 33 unproductive boreal lakes of different humic content, situated along a latitudinal gradient (57°N to 64°N) in Sweden. The lakes were sampled four times during one year, and analyzed on a wide variety of water chemistry parameters. With only one exception, all lakes were supersaturated with CO2 with respect to the atmosphere at all sampling occasions. pCO2 was closely related to the DOC concentration in lakes, which in turn was mainly regulated by catchment characteristics. This pattern was similar along the latitudinal gradient and at different seasons of the year, indicating that it is valid for a variety of climatic conditions within the boreal forest zone. We suggest that landscape characteristics determine the accumulation and subsequent supply of allochthonous organic matter from boreal catchments to lakes, which in turn results in boreal lakes becoming net sources of atmospheric CO2.

Place, publisher, year, edition, pages
2003. Vol. 9, no 4, 630-641 p.
URN: urn:nbn:se:umu:diva-4405DOI: 10.1046/j.1365-2486.2003.00619.xOAI: diva2:143492
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-KristinJansson, Mats
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Ecology and Environmental ScienceDepartment of Ecology and Environmental Sciences

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