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| Titel |
Measurement of Isotopic CO2 in Dissolved Inorganic Carbons of Water Samples from Various Origins Using Wavelength-Scanned Cavity Ring-Down Spectrophotometer |
| VerfasserIn |
N. Saad, I. Green, C. Rella, A. Van Pelt |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250024241
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| Zusammenfassung |
| Given the growing need to monitor the containment efficiency of CO2 sequestration storage sites through the use of field-deployable instruments, we report here on the novel employment of a small footprint Wavelength-Scanned Cavity Ring-Down Spectrometer (WS-CRDS) for the measurement of the isotopic CO2 signature of dissolved inorganic carbon (DIC). The above system is interfaced to an online aqueous sample treatment device in which 10% H3PO4 solution is bubbled through exetainer vials containing water samples to liberate gaseous CO2 from dissolved inorganics. The WS-CRDS instrument is used to measure the isotopic carbon signature of the liberated CO2, which can then be used to trace the carbonates back to their point of origin. In a first phase, a manual process was employed in which DIC containing samples were acidified and the evolved CO2 was collected inside gas pillows. The gas pillows were then connected to the inlet of the isotopic WS-CRDS instrument for carbon ratio measurement. In a second phase, the acidification process was partially automated through the use of a software-controlled sample preparation system directly connected to the gas inlet of the isotopic WS-CRDS instrument via manual one three-way and one 2-position four-port valving system. A measurement precision of the isotopic ratio of less than 1 permil was achieved in minutes of measurement time. Such precision readily distinguishes the isotopic carbon signatures from three DIC samples collected from various sites in Northern California and presents a rugged and inexpensive analytical instrumentation alternative to the traditional use of methods based on the more complex isotope ratio mass spectrometry technique. |
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