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Production and emission of CO2 in two unproductive lakes in northern Sweden

Åberg, Jan, 1977- (author)
Umeå universitet,Institutionen för ekologi, miljö och geovetenskap
Jansson, Mats, Professor (thesis advisor)
Umeå universitet,Institutionen för ekologi, miljö och geovetenskap
Jonsson, Anders, Doktor (thesis advisor)
Umeå universitet,Institutionen för ekologi, miljö och geovetenskap
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Bastviken, David, Docent (opponent)
Linköpings universitet, Tema vatten i natur och samhälle
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 (creator_code:org_t)
ISBN 9789172648784
Umeå : Institutionen för Ekologi, miljö och geovetenskap, Umeå universitet, 2009
English 28 s.
  • Doctoral thesis (other academic/artistic)
Abstract Subject headings
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  • 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.

Subject headings

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)
NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)
NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Naturgeografi (hsv//swe)
NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Physical Geography (hsv//eng)

Keyword

lake
carbon dioxide
organic carbon
inorganic carbon
boreal
arctic
DOC
DIC
CO2
emission
thermal stratification
allochthonous organic carbon
Freshwater ecology
Limnisk ekologi
Physical geography
Naturgeografi
naturgeografi
Physical Geography

Publication and Content Type

vet (subject category)
dok (subject category)

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