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| Titel |
A centrifugal ice microtome for measurements of atmospheric CO2 on air trapped in polar ice cores |
| VerfasserIn |
B. Bereiter, T. F. Stocker, H. Fischer |
| 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 ; 6, no. 2 ; Nr. 6, no. 2 (2013-02-07), S.251-262 |
| Datensatznummer |
250017387
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| Publikation (Nr.) |
 copernicus.org/amt-6-251-2013.pdf |
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| Zusammenfassung |
| For atmospheric CO2 reconstructions using ice cores, the technique to
release the trapped air from the ice samples is essential for the precision
and accuracy of the measurements. We present here a new dry extraction
technique in combination with a new gas analytical system that together show
significant improvements with respect to current systems. Ice samples
(3–15 g) are pulverised using a novel centrifugal ice microtome (CIM) by
shaving the ice in a cooled vacuum chamber (−27 °C) in which no
friction occurs due to the use of magnetic bearings. Both, the shaving
principle of the CIM and the use of magnetic bearings have not been applied
so far in this field. Shaving the ice samples produces finer ice powder and
releases a minimum of 90% of the trapped air compared to
50%–70% when needle crushing is employed. In addition, the
friction-free motion with an optimized design to reduce contaminations of the
inner surfaces of the device result in a reduced system offset of about
2.0 ppmv compared to 4.9 ppmv. The gas analytical part shows a
higher precision than the corresponding part of our previous system by a factor of two, and
all processes except the loading and cleaning of the CIM now run
automatically. Compared to our previous system, the complete system shows a 3
times better measurement reproducibility of about 1.1 ppmv
(1 σ) which is similar to the best reproducibility of other systems
applied in this field. With this high reproducibility, no replicate
measurements are required anymore for most future measurement campaigns
resulting in a possible output of 12–20 measurements per day compared to a
maximum of 6 with other systems. |
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