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| Titel |
High resolution, high precision, simultaneous measurements of δD and δ¹⁸O using a CRDS analyzer with an ultrasonic nebulizer sample preparation module. |
| VerfasserIn |
Vasileios Gkinis, Valerie Morrie, Tyler Jones, Bruce Vaughn, James White |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250071939
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| Zusammenfassung |
| The recent advent of commercial Cavity Ring Down Spectroscopy (CRDS) has initiated the
development of numerous new Continuous Flow Analysis (CFA) methods for high
resolution, high precision measurements of greenhouse gas concentrations and isotopic
ratios of water from ice cores. Depending on the sample preparation method and the
calibration schemes applied, these new systems have proved to be precise, accurate
and extremely versatile, allowing for high quality measurements performed in the
field.
However there are still challenges to be addressed. Measurements need to be accurately
calibrated with respect to international standards (SMOW – SLAP in the case of water). A
proper characterization of the precision and the accuracy of a system is another task that
needs to be performed. Apparent sample diffusion affects the produced signals in ways that
are unique not only to different systems but also to different implementations of
the same system, reducing the resolution that can be obtained. Parameters such as
melt rate, sample flow, cavity volume and the method of sample preparation can
significantly alter the performance of the analytical method. These effects can be
accurately characterized with a series of experiments and consequently corrected
for using spectral filtering techniques. Last but not least, proper monitoring of the
melting process is necessary in order to assign an ice core depth scale on the data
produced.
In this work we present an integrated system for high resolution, high precision water
isotopic analysis from a continuously melted ice core sample, using a commercial CRDS
analyzer (Picarro L2130 -i) . The system utilizes an ultrasonic concentric nebulizer in order
to achieve complete fractionation free vaporization of the continuous flow water sample. An
adjacent home made calibration module allows for the injection of local standards accurately
characterized with respect to the SMOW – SLAP scale. The system has been used for the
high resolution isotopic analysis of 13 Ã 13mm ice rods sampled from the WAIS
divide ice core. We present how we progress from raw data to SMOW and depth
calibrated simultaneous measurements of δD and δ18O). We discuss the achieved
precision for the second order parameter of the Deuterium excess and propose ways to
deconvolve the produced data for apparent smoothing effects using a Wiener filtering ap |
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