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Variations in pCO2 during summer in the surface water of an unproductive lake in northern Sweden
Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
2007 (engelsk)Inngår i: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, Vol. 59, nr 5, 797-803 s.Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Unproductive lakes are generally supersaturated with carbon dioxide (CO2) and emit CO2 to the atmosphere continuously during ice-free periods. However, temporal variation of the partial pressure of CO2 (pCO2) and thus of CO2 evasion to atmosphere is poorly documented. We therefore carried out temporally high-resolution (every 6 h) measurements of the pCO2 using an automated logger system in the surface water of a subarctic, unproductive, lake in the birch forest belt. The study period was June–September 2004. We found that the pCO2 showed large seasonal variation, but low daily variation. The seasonal variation was likely mainly caused by variations in input and mineralization of allochthonous organic matter. Stratification depth probably also influenced pCO2 of the surface water by controlling the volume in which mineralization of dissolved organic carbon (DOC) occurred. In lakes, with large variations in pCO2, as in our study lake a high (weekly) sampling intensity is recommended for obtaining accurate estimates of the evasion of CO2.

sted, utgiver, år, opplag, sider
2007. Vol. 59, nr 5, 797-803 s.
Identifikatorer
URN: urn:nbn:se:umu:diva-20329DOI: 10.1111/j.1600-0889.2007.00307.xOAI: oai:DiVA.org:umu-20329DiVA: diva2:208421
Tilgjengelig fra: 2009-03-18 Laget: 2009-03-18 Sist oppdatert: 2009-11-10
Inngår i avhandling
1. Production and emission of CO2 in two unproductive lakes in northern Sweden
Åpne denne publikasjonen i ny fane eller vindu >>Production and emission of CO2 in two unproductive lakes in northern Sweden
2009 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Unproductive lakes are one of few natural landscape compartments with net release of carbon to the atmosphere. Lakes also generally decrease the net terrestrial carbon uptake, since most of the CO2 production in unproductive lakes are derived from organic carbon produced on land (e.g. in forests). High latitude lakes are predicted to be particularly affected by the global climate change. The carbon cycling in these lakes and their role in the landscape are therefore important to study.

In this thesis, carbon turnover processes were studied in two lakes above the arctic circle (Lake Diktar-Erik and Lake Merasjärvi) in year 2004 and 2005. Both lakes were net heterotrophic, with large variations in CO2 concentrations both on shorter (30min) and longer (24h) time-scales. The pelagic habitat supported a major part of the net production of CO2, with larger dynamics in the CO2 production than the sediments. The CO2 variations of the surface water were related to respiration of allochthonous organic carbon, and were affected by the concentration and quality of the DOC, as well as the whole lake water temperatures, and vertical water movements.

The emission of CO2 from Lake Merasjärvi was measured with the eddy covariance tech­nique. The results showed that the gas transfer rate during moderate winds were higher than expected, causing the two most commonly used models to underestimate the long term fluxes of CO2 from the lake.

Taken together, the results of the thesis show that the studied lakes contributed to bring terrestrial organic carbon back into the atmosphere, driven by a substantial internal CO2 production based on mineralization of allochthonous organic carbon. Major results are that the eddy covariance technique indicated that commonly used models tend to underestimate the net release rate of CO2 from lakes to the atmosphere, and that the lake CO2 dynamics can be the results of interactions between biogeochemical and physical processes in the lake water.

sted, utgiver, år, opplag, sider
Umeå: Institutionen för Ekologi, miljö och geovetenskap, Umeå universitet, 2009. 28 s.
Emneord
lake, carbon dioxide, organic carbon, inorganic carbon, boreal, arctic, DOC, DIC, CO2, emission, thermal stratification, allochthonous organic carbon
HSV kategori
Forskningsprogram
naturgeografi
Identifikatorer
urn:nbn:se:umu:diva-26967 (URN)978-91-7264-878-4 (ISBN)
Disputas
2009-12-03, Naturvetarhuset hörsal N450, Johan Bures Väg, Umeå universitet, Umeå, 10:00 (svensk)
Opponent
Veileder
Tilgjengelig fra: 2009-11-12 Laget: 2009-11-04 Sist oppdatert: 2009-11-13bibliografisk kontrollert

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