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| Titel |
New online method for water isotope analysis of speleothem fluid inclusions using laser absorption spectroscopy (WS-CRDS) |
| VerfasserIn |
S. Affolter, D. Fleitmann, M. Leuenberger |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 4 ; Nr. 10, no. 4 (2014-07-04), S.1291-1304 |
| Datensatznummer |
250117012
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| Publikation (Nr.) |
 copernicus.org/cp-10-1291-2014.pdf |
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| Zusammenfassung |
A new online method to analyse water isotopes of speleothem fluid inclusions
using a wavelength scanned cavity ring down spectroscopy (WS-CRDS) instrument
is presented. This novel technique allows us simultaneously
to measure hydrogen and oxygen isotopes for
a released aliquot of water. To do so, we designed a new simple line that
allows the online water extraction and isotope analysis of speleothem
samples. The specificity of the method lies in the fact that fluid inclusions
release is made on a standard water background, which mainly improves the
δ D robustness.
To saturate the line, a peristaltic pump continuously injects standard water
into the line that is permanently heated to 140 °C and flushed with
dry nitrogen gas. This permits instantaneous and complete vaporisation of the
standard water, resulting in an artificial water background with well-known
δ D and δ18O values. The speleothem sample is placed in a
copper tube, attached to the line, and after system stabilisation it is crushed
using a simple hydraulic device to liberate speleothem fluid inclusions
water. The released water is carried by the nitrogen/standard water gas
stream directly to a Picarro L1102-i for isotope determination. To test the
accuracy and reproducibility of the line and to measure standard water during
speleothem measurements, a syringe injection unit was added to the line.
Peak evaluation is done similarly as in gas chromatography to obtain &delta
D; and δ18O isotopic compositions of measured water aliquots.
Precision is better than 1.5 ‰ for δ D and 0.4 ‰ for
δ18O for water measurements for an extended range (−210 to
0 ‰ for δ D and −27 to 0 ‰ for δ18O)
primarily dependent on the amount of water released from speleothem fluid
inclusions and secondarily on the isotopic composition of the sample. The
results show that WS-CRDS technology is suitable for speleothem fluid
inclusion measurements and gives results that are comparable to the isotope
ratio mass spectrometry (IRMS) technique. |
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