F.: High-resolution δ13C measurement on ancient air extracted from less than 10 cm3 of ice
We have developed a new method for δ13C analysis for very small air amounts of less than 0.5 cc STP, corresponding to less than 10 gram of ice. It is based on the needle-crasher technique, which we routinely use for CO2 concentration measurements by infrared laser absorption. The extracted air is sl...
| Main Authors: | , , , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.629.7818 http://www.climate.unibe.ch/~mcl/abstracts/AbstractSendai01_eyer.pdf |
| Summary: | We have developed a new method for δ13C analysis for very small air amounts of less than 0.5 cc STP, corresponding to less than 10 gram of ice. It is based on the needle-crasher technique, which we routinely use for CO2 concentration measurements by infrared laser absorption. The extracted air is slowly expanded into a large volume through a water trap held at –90°C. This sampled air is then carried by a strong high helium flux through a modified Precon system of Thermo-Finnigan to separate CO2 from the air and to inject the small pure CO2 gas in a low helium stream via an open split device to a Delta Plus XL mass spectrometer. The overall precision based on replicates of standard air is significantly better than 0.1 ‰ for a single analysis and is further improved by a triplicate measurement of the same sample through a specially designed gas splitter. We have used this new method for Alpine ice core samples and started recently with investigations on polar ice cores. We hope to present in Sendai, Japan a δ13C record with an extremely high depth resolution. 1. |
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