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| Titel |
Natural abundance and 13C-enriched characterisation of atmospheric methane uptake in a forest soil |
| VerfasserIn |
Peter Maxfield, Edward Hornibrook, Richard Evershed |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250084017
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| Zusammenfassung |
| Whilst much attention is focused on CH4 emission inventories, CH4 sinks are sometimes
overlooked and not accurately accounted for in national budgets. Two primary reasons for
this disjunction include uncertainties about the magnitude and mechanism of terrestrial CH4
oxidation, and an under-appreciation of the quantity of CH4 that is removed from the
atmosphere by microorganisms. These uncertainties in part are caused by a lack of
high-resolution field data that quantify microbial soil CH4 sink. To fully characterize the soil
CH4 sink, isotopic fractionation of CH4during uptake and the fate of CH4 carbon
following oxidation by soil microorganisms should be quantified in addition to CH4
fluxes.
Here we report on field tests studying CH4 uptake in soil using a Picarro G2201-i
cavity ringdown spectrometer (CRDS). Short term atmospheric CH4 uptake was
continuously measured in a forest soil in Leigh Woods, UK where the soil methanotrophic
community and soil CH4 uptake kinetic isotopic effect (KIE) had been previously
quantified using stable isotope probing and conventional stable isotope analysis
techniques (Maxfield et al., 2008). Two methodological approaches were tested: (i) direct
measurement of the soil CH4 uptake KIE at subambient CH4 concentrations, and (ii)
methanotrophic carbon conversion efficiency (CCE) where CCE was evaluated through
monitoring the direct conversion of 13C-labelled CH4 to 13C-labelled CO2. The
suitability of the G2201-i analyzer as a continuous isotopic CH4 and CO2 analyzer
for use at both subambient CH4 concentrations and high 13C-enrichments will be
discussed.
Maxfield, P.J., Evershed, R.P. and Hornibrook, E.R.C. (2008) Physical and
biological controls on the in situ kinetic isotope effect associated with oxidation of
atmospheric CH4 in mineral soils. Environmental Science & Technology, 42, 7824-7830. |
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