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| Titel |
Water isotopic ratios from a continuously melted ice core sample |
| VerfasserIn |
V. Gkinis, T. J. Popp, T. Blunier, M. Bigler, S. Schüpbach, E. Kettner, S. J. Johnsen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 4, no. 11 ; Nr. 4, no. 11 (2011-11-24), S.2531-2542 |
| Datensatznummer |
250002139
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| Publikation (Nr.) |
 copernicus.org/amt-4-2531-2011.pdf |
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| Zusammenfassung |
| A new technique for on-line high resolution isotopic analysis of
liquid water, tailored for ice core studies is presented. We built an
interface between a Wavelength Scanned Cavity Ring Down Spectrometer
(WS-CRDS) purchased from Picarro Inc. and a Continuous Flow Analysis (CFA) system. The system
offers the possibility to perform simultaneuous water isotopic
analysis of δ18O and δD on a continuous stream of liquid water as
generated from a continuously melted ice rod. Injection of
sub μl amounts of liquid water is achieved by pumping
sample through a fused silica capillary and instantaneously vaporizing
it with 100% efficiency in a~home made oven at a temperature of
170 °C. A calibration procedure allows for proper reporting
of the data on the VSMOW–SLAP scale. We apply the necessary corrections
based on the assessed performance of the system regarding instrumental
drifts and dependance on the water concentration in the optical cavity.
The melt rates are
monitored in order to assign a depth scale to the measured isotopic
profiles. Application of spectral methods yields the combined
uncertainty of the system at below 0.1‰ and 0.5‰
for δ18O and δD, respectively. This performance is comparable to
that achieved with mass spectrometry. Dispersion of the sample in the
transfer lines limits the temporal resolution of the technique. In this work
we investigate and assess these dispersion effects. By using an
optimal filtering method we show how the measured profiles can be
corrected for the smoothing effects resulting from the sample
dispersion. Considering the significant advantages the technique
offers, i.e. simultaneuous measurement of δ18O and δD,
potentially in combination with chemical components that are
traditionally measured on CFA systems, notable reduction on analysis
time and power consumption, we consider it as an alternative to
traditional isotope ratio mass spectrometry with the possibility to be
deployed for field ice core studies. We present data acquired in the field
during the 2010 season as part of the NEEM deep ice core drilling project
in North Greenland. |
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