Change search
ReferencesLink to record
Permanent link

Direct link
Mass fluxes and isofluxes of methane (ch4) at a new hampshire fen measured by a continuous wave quantum cascade laser spectrometer
Show others and affiliations
2012 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 117, D10301- p.Article in journal (Refereed) Published
Abstract [en]

We have developed a mid-infrared continuous-wave quantum cascade laser direct-absorption spectrometer (QCLS) capable of high frequency (>= 1 Hz) measurements of (CH4)-C-12 and (CH4)-C-13 isotopologues of methane (CH4) with in situ 1-s RMS delta C-13(CH4) precision of 1.5 parts per thousand and Allan-minimum precision of 0.2 parts per thousand. We deployed this QCLS in a well-studied New Hampshire fen to compare measurements of CH4 isoflux by eddy covariance (EC) to Keeling regressions of data from automated flux chamber sampling. Mean CH4 fluxes of 6.5 +/- 0.7 mg CH4 m(-2) hr(-1) over two days of EC sampling in July, 2009 were indistinguishable from mean autochamber CH4 fluxes (6.6 +/- 0.8 mgCH(4) m(-2) hr(-1)) over the same period. Mean delta C-13(CH4) composition of emitted CH4 calculated using EC isoflux methods was -71 +/- 8 parts per thousand (95% C.I.) while Keeling regressions of 332 chamber closing events over 8 days yielded a corresponding value of -64.5 +/- 0.8 parts per thousand Ebullitive fluxes, representing similar to 10% of total CH4 fluxes at this site, were on average 1.2 parts per thousand enriched in C-13 compared to diffusive fluxes. CH4 isoflux time series have the potential to improve process-based understanding of methanogenesis, fully characterize source isotopic distributions, and serve as additional constraints for both regional and global CH4 modeling analysis.

Place, publisher, year, edition, pages
2012. Vol. 117, D10301- p.
National Category
Meteorology and Atmospheric Sciences
URN: urn:nbn:se:su:diva-79756DOI: 10.1029/2011JD016960ISI: 000304260300002OAI: diva2:551995


Available from: 2012-09-12 Created: 2012-09-11 Last updated: 2012-09-12Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Crill, Patrick M.
By organisation
Department of Geological Sciences
In the same journal
Journal of Geophysical Research
Meteorology and Atmospheric Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 26 hits
ReferencesLink to record
Permanent link

Direct link