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Gas transfer rate and CO2 flux between an unproductive lake and the atmosphere 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.
2008 (engelsk)Inngår i: Journal of Geophysical Research - Biogeosciences, Vol. 113, Art.no. G04006- s.Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Measurements of the gas transfer rate of CO2 between lake water and the atmosphere present a critical problem for the understanding of lake ecosystem carbon balances and landscape carbon budgets. We present calculations of the gas transfer rate of CO2 from direct measurements of the CO2 flux using an eddy covariance system and concurrent measurements of the concentration of CO2 in the surface water in a lake in boreal zone of northern Sweden. The measured gas transfer rate was different, and in general larger than, rates obtained with the most commonly used models for prediction of the gas transfer rate in lakes. The normalized gas transfer rate (k600EC) was well predicted from the wind speed at 10 m height if data were bin classed into wind classes of 1 m/s for winds above 1 m/s. Unbinned data were also correlated to wind speed but also to water temperature, water temperature/air temperature ratio and to incoming photosynthetic active radiation (PAR). These relationships could reflect effects of both physico-chemical reactions and biological activity.

sted, utgiver, år, opplag, sider
2008. Vol. 113, Art.no. G04006- s.
Identifikatorer
URN: urn:nbn:se:umu:diva-11368DOI: 10.1029/2008JG000688OAI: oai:DiVA.org:umu-11368DiVA: diva2:151039
Tilgjengelig fra: 2008-12-16 Laget: 2008-12-16 Sist oppdatert: 2009-11-11bibliografisk kontrollert
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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