Measurement of methane and carbon dioxide fluxes from peatland ecosystems by the conditional-sampling technique

I J Beverland, J B Moncrieff, D H Oneill, K J Hargreaves, R Milne

Research output: Contribution to journalArticle

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Abstract

The conditional sampling method was used to measure methane (CH4) and carbon dioxide (CO2) fluxes from peatlands in northern Scotland. Preliminary data were obtained using a simple system. Subsequent automation made continuous nux-measurements possible. Observed CH4 fluxes were in the range -70 to +110 mu mol m(-2)h(-1) with a mean flux of 23 mu mol m(-2)h(-1). Peak photosynthetic CO2 fluxes were in the range -10 to -30 mmol m(-2) h(-1). Nocturnal respiration ranged from 0 to +10 mmol m(-2) h(-1). The conditional sampling observations showed reasonable agreement with measurements of flux by eddy-covariance, gradient and aircraft methods. Error analyses and laboratory tests were conducted to determine the precision of the flux-measurement system. The dominant error was associated with the determination of the mixing-ratio difference in conditionally-sampled updraught and downdraught air. The standard error of the difference for CH4 was typically 0.15 ng g(-1) (0.3 parts in 10(9) (p.p.b.))using a careful high-repetition sampling strategy with a modified gas chromatographic/flame ionization detector system. Under typical daytime atmospheric conditions this corresponded to a standard error in the flux measurement of 10 mu mol m(-2)h(-1), which is consistent with field observations. The empirical beta factor in the conditional sampling equation was found to be insensitive to changes in turbulence intensity and atmospheric stability. Simple upscaling models were used to estimate annual carbon-fluxes to Great Britain's peatlands of -0.5 Mt of carbon in the form of CO2 and 18 kt in the form of methane.

LanguageEnglish
Pages819-838
Number of pages20
JournalQuarterly Journal of the Royal Meteorological Society
Volume122
Issue number532
DOIs
Publication statusPublished - Apr 1996

Fingerprint

peatland
carbon dioxide
methane
ecosystem
sampling
flux measurement
upscaling
updraft
eddy covariance
carbon flux
automation
mixing ratio
aircraft
respiration
ionization
turbulence
sampling technique
carbon
air
gas

Keywords

  • atmosphere/land-surface exchange
  • boundary-layer turbulence
  • carbon dioxide
  • conditional sampling
  • methane
  • peatlands
  • trace-gas fluxes
  • upscaling
  • water
  • emissions

Cite this

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title = "Measurement of methane and carbon dioxide fluxes from peatland ecosystems by the conditional-sampling technique",
abstract = "The conditional sampling method was used to measure methane (CH4) and carbon dioxide (CO2) fluxes from peatlands in northern Scotland. Preliminary data were obtained using a simple system. Subsequent automation made continuous nux-measurements possible. Observed CH4 fluxes were in the range -70 to +110 mu mol m(-2)h(-1) with a mean flux of 23 mu mol m(-2)h(-1). Peak photosynthetic CO2 fluxes were in the range -10 to -30 mmol m(-2) h(-1). Nocturnal respiration ranged from 0 to +10 mmol m(-2) h(-1). The conditional sampling observations showed reasonable agreement with measurements of flux by eddy-covariance, gradient and aircraft methods. Error analyses and laboratory tests were conducted to determine the precision of the flux-measurement system. The dominant error was associated with the determination of the mixing-ratio difference in conditionally-sampled updraught and downdraught air. The standard error of the difference for CH4 was typically 0.15 ng g(-1) (0.3 parts in 10(9) (p.p.b.))using a careful high-repetition sampling strategy with a modified gas chromatographic/flame ionization detector system. Under typical daytime atmospheric conditions this corresponded to a standard error in the flux measurement of 10 mu mol m(-2)h(-1), which is consistent with field observations. The empirical beta factor in the conditional sampling equation was found to be insensitive to changes in turbulence intensity and atmospheric stability. Simple upscaling models were used to estimate annual carbon-fluxes to Great Britain's peatlands of -0.5 Mt of carbon in the form of CO2 and 18 kt in the form of methane.",
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Measurement of methane and carbon dioxide fluxes from peatland ecosystems by the conditional-sampling technique. / Beverland, I J ; Moncrieff, J B ; Oneill, D H ; Hargreaves, K J ; Milne, R .

In: Quarterly Journal of the Royal Meteorological Society, Vol. 122, No. 532, 04.1996, p. 819-838.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Measurement of methane and carbon dioxide fluxes from peatland ecosystems by the conditional-sampling technique

AU - Beverland, I J

AU - Moncrieff, J B

AU - Oneill, D H

AU - Hargreaves, K J

AU - Milne, R

PY - 1996/4

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N2 - The conditional sampling method was used to measure methane (CH4) and carbon dioxide (CO2) fluxes from peatlands in northern Scotland. Preliminary data were obtained using a simple system. Subsequent automation made continuous nux-measurements possible. Observed CH4 fluxes were in the range -70 to +110 mu mol m(-2)h(-1) with a mean flux of 23 mu mol m(-2)h(-1). Peak photosynthetic CO2 fluxes were in the range -10 to -30 mmol m(-2) h(-1). Nocturnal respiration ranged from 0 to +10 mmol m(-2) h(-1). The conditional sampling observations showed reasonable agreement with measurements of flux by eddy-covariance, gradient and aircraft methods. Error analyses and laboratory tests were conducted to determine the precision of the flux-measurement system. The dominant error was associated with the determination of the mixing-ratio difference in conditionally-sampled updraught and downdraught air. The standard error of the difference for CH4 was typically 0.15 ng g(-1) (0.3 parts in 10(9) (p.p.b.))using a careful high-repetition sampling strategy with a modified gas chromatographic/flame ionization detector system. Under typical daytime atmospheric conditions this corresponded to a standard error in the flux measurement of 10 mu mol m(-2)h(-1), which is consistent with field observations. The empirical beta factor in the conditional sampling equation was found to be insensitive to changes in turbulence intensity and atmospheric stability. Simple upscaling models were used to estimate annual carbon-fluxes to Great Britain's peatlands of -0.5 Mt of carbon in the form of CO2 and 18 kt in the form of methane.

AB - The conditional sampling method was used to measure methane (CH4) and carbon dioxide (CO2) fluxes from peatlands in northern Scotland. Preliminary data were obtained using a simple system. Subsequent automation made continuous nux-measurements possible. Observed CH4 fluxes were in the range -70 to +110 mu mol m(-2)h(-1) with a mean flux of 23 mu mol m(-2)h(-1). Peak photosynthetic CO2 fluxes were in the range -10 to -30 mmol m(-2) h(-1). Nocturnal respiration ranged from 0 to +10 mmol m(-2) h(-1). The conditional sampling observations showed reasonable agreement with measurements of flux by eddy-covariance, gradient and aircraft methods. Error analyses and laboratory tests were conducted to determine the precision of the flux-measurement system. The dominant error was associated with the determination of the mixing-ratio difference in conditionally-sampled updraught and downdraught air. The standard error of the difference for CH4 was typically 0.15 ng g(-1) (0.3 parts in 10(9) (p.p.b.))using a careful high-repetition sampling strategy with a modified gas chromatographic/flame ionization detector system. Under typical daytime atmospheric conditions this corresponded to a standard error in the flux measurement of 10 mu mol m(-2)h(-1), which is consistent with field observations. The empirical beta factor in the conditional sampling equation was found to be insensitive to changes in turbulence intensity and atmospheric stability. Simple upscaling models were used to estimate annual carbon-fluxes to Great Britain's peatlands of -0.5 Mt of carbon in the form of CO2 and 18 kt in the form of methane.

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KW - boundary-layer turbulence

KW - carbon dioxide

KW - conditional sampling

KW - methane

KW - peatlands

KW - trace-gas fluxes

KW - upscaling

KW - water

KW - emissions

U2 - 10.1002/qj.49712253203

DO - 10.1002/qj.49712253203

M3 - Article

VL - 122

SP - 819

EP - 838

JO - Quarterly Journal of the Royal Meteorological Society

T2 - Quarterly Journal of the Royal Meteorological Society

JF - Quarterly Journal of the Royal Meteorological Society

SN - 0035-9009

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ER -