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| Titel |
Very high precision and accuracy analysis of triple isotopic ratios of water. A critical instrumentation comparison study. |
| VerfasserIn |
Vasileios Gkinis, Christian Holme, Valerie Morris, Abigail Grace Thayer, Bruce Vaughn, Helle Astrid Kjær, Paul Vallelonga, Marius Simonsen, Camilla Marie Jensen, Anders Svensson, Niccolo Maffrezzoli, Bo Vinther, Remi Dallmayr |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143385
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| Publikation (Nr.) |
 EGU/EGU2017-7097.pdf |
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| Zusammenfassung |
| We present a performance comparison study between two state of the art Cavity Ring Down
Spectrometers (Picarro L2310-i, L2140-i). The comparison took place during the Continuous
Flow Analysis (CFA) campaign for the measurement of the Renland ice core, over a period of
three months. Instant and complete vaporisation of the ice core melt stream, as well as of
in-house water reference materials is achieved by accurate control of microflows
of liquid into a homemade calibration system by following simple principles of
the Hagen-Poiseuille law. Both instruments share the same vaporisation unit in a
configuration that minimises sample preparation discrepancies between the two
analyses.
We describe our SMOW-SLAP calibration and measurement protocols for such a CFA
application and present quality control metrics acquired during the full period of the
campaign on a daily basis. The results indicate an unprecedented performance for all 3
isotopic ratios (δ2H, δ17O, δ18O ) in terms of precision, accuracy and resolution. We also
comment on the precision and accuracy of the second order excess parameters of HD16O
and H217O over H218O (Dxs, Δ17O ). To our knowledge these are the first reported CFA
measurements at this level of precision and accuracy for all three isotopic ratios. Differences
on the performance of the two instruments are carefully assessed during the measurement and
reported here.
Our quality control protocols extend to the area of low water mixing ratios, a regime in
which often atmospheric vapour measurements take place and Cavity Ring Down Analysers
show a poorer performance due to the lower signal to noise ratios. We address such issues and
propose calibration protocols from which water vapour isotopic analyses can benefit from. |
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