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Methane fluxes from a small boreal lake measured with the eddy covariance method

Podgrajsek, E. ; Sahlee, Erik ; Bastviken, David ; Natchimuthu, Sivakiruthika ; Kljun, Natascha LU orcid ; Chmiel, H.E. ; Klemedtsson, Leif and Rutgersson, Anna (2016) In Limnology and Oceanography 61. p.41-50
Abstract
Fluxes of methane, CH4, were measured with the eddy covariance (EC) method at a small boreal lake in Sweden. The mean CH4 flux during the growing season of 2013 was 20.1 nmol m−2 s−1 and the median flux was 16 nmol m−2 s−1 (corresponding to 1.7 mmol m−2 d−1 and 1.4 mmol m−2 d−1). Monthly mean values of CH4 flux measured with the EC method were compared with fluxes measured with floating chambers (FC) and were in average 62% higher over the whole study period. The difference was greatest in April partly because EC, but not FC, accounted for fluxes due to ice melt and a subsequent lake mixing event. A footprint analysis revealed that the EC footprint included primarily the shallow side of the lake with a major inlet. This inlet harbors... (More)
Fluxes of methane, CH4, were measured with the eddy covariance (EC) method at a small boreal lake in Sweden. The mean CH4 flux during the growing season of 2013 was 20.1 nmol m−2 s−1 and the median flux was 16 nmol m−2 s−1 (corresponding to 1.7 mmol m−2 d−1 and 1.4 mmol m−2 d−1). Monthly mean values of CH4 flux measured with the EC method were compared with fluxes measured with floating chambers (FC) and were in average 62% higher over the whole study period. The difference was greatest in April partly because EC, but not FC, accounted for fluxes due to ice melt and a subsequent lake mixing event. A footprint analysis revealed that the EC footprint included primarily the shallow side of the lake with a major inlet. This inlet harbors emergent macrophytes that can mediate high CH4 fluxes. The difference between measured EC and FC fluxes can hence be explained by different footprint areas, where the EC system “sees” the part of the lake presumably releasing higher amounts of CH4. EC also provides more frequent measurements than FC and hence more likely captures ebullition events. This study shows that small lakes have CH4 fluxes that are highly variable in time and space. Based on our findings we suggest to measure CH4 fluxes from lakes as continuously as possible and to aim for covering as much of the lakes surface as possible, independently of the selected measuring technique. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Limnology and Oceanography
volume
61
pages
9 pages
publisher
ASLO
external identifiers
  • scopus:84952815421
ISSN
1939-5590
DOI
10.1002/lno.10245
language
English
LU publication?
no
id
f922f7f0-b0d3-42f9-b7e4-244db03c4a4b
date added to LUP
2018-06-12 12:49:41
date last changed
2022-04-02 00:38:06
@article{f922f7f0-b0d3-42f9-b7e4-244db03c4a4b,
  abstract     = {{Fluxes of methane, CH4, were measured with the eddy covariance (EC) method at a small boreal lake in Sweden. The mean CH4 flux during the growing season of 2013 was 20.1 nmol m−2 s−1 and the median flux was 16 nmol m−2 s−1 (corresponding to 1.7 mmol m−2 d−1 and 1.4 mmol m−2 d−1). Monthly mean values of CH4 flux measured with the EC method were compared with fluxes measured with floating chambers (FC) and were in average 62% higher over the whole study period. The difference was greatest in April partly because EC, but not FC, accounted for fluxes due to ice melt and a subsequent lake mixing event. A footprint analysis revealed that the EC footprint included primarily the shallow side of the lake with a major inlet. This inlet harbors emergent macrophytes that can mediate high CH4 fluxes. The difference between measured EC and FC fluxes can hence be explained by different footprint areas, where the EC system “sees” the part of the lake presumably releasing higher amounts of CH4. EC also provides more frequent measurements than FC and hence more likely captures ebullition events. This study shows that small lakes have CH4 fluxes that are highly variable in time and space. Based on our findings we suggest to measure CH4 fluxes from lakes as continuously as possible and to aim for covering as much of the lakes surface as possible, independently of the selected measuring technique.}},
  author       = {{Podgrajsek, E. and Sahlee, Erik and Bastviken, David and Natchimuthu, Sivakiruthika and Kljun, Natascha and Chmiel, H.E. and Klemedtsson, Leif and Rutgersson, Anna}},
  issn         = {{1939-5590}},
  language     = {{eng}},
  month        = {{11}},
  pages        = {{41--50}},
  publisher    = {{ASLO}},
  series       = {{Limnology and Oceanography}},
  title        = {{Methane fluxes from a small boreal lake measured with the eddy covariance method}},
  url          = {{http://dx.doi.org/10.1002/lno.10245}},
  doi          = {{10.1002/lno.10245}},
  volume       = {{61}},
  year         = {{2016}},
}