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Mass fluxes and iso...
Mass fluxes and isofluxes of methane (ch4) at a new hampshire fen measured by a continuous wave quantum cascade laser spectrometer
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Santoni, Gregory W. (författare)
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Lee, Ben H. (författare)
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Goodrich, Jordan P. (författare)
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Varner, Ruth K. (författare)
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- Crill, Patrick M. (författare)
- Stockholms universitet,Institutionen för geologiska vetenskaper
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McManus, J. Barry (författare)
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Nelson, David D. (författare)
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Zahniser, Mark S. (författare)
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Wofsy, Steven C. (författare)
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(creator_code:org_t)
- 2012
- 2012
- Engelska.
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 117, s. D10301-
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- 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.
Ämnesord
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)
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