 |
| Titel |
FieldSpec: A field portable mass spectrometer prototype for high frequency measurements of δ2H and δ18O ratios in water |
| VerfasserIn |
Veneranda López Días, Hung Quang Hoang, Núria Martínez-Carreras, Francois Barnich, Tom Wirtz, Laurent Pfister, Jeffrey McDonnell |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250134807
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| Publikation (Nr.) |
 EGU/EGU2016-15573.pdf |
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| Zusammenfassung |
| Hydrological studies relying on stable water isotopes to better understand water sources,
flowpaths and transit times are currently limited by the coarse temporal resolution of
sampling and analysis protocols. At present, two kinds of lab-based instruments are
used : (i) the standard isotope ratio mass spectrometers (IRMS) [1] and (ii) the
laser-based instruments [2, 3]. In both cases, samples need to be collected in the field
and then transferred to the laboratory for the water isotopic ratio measurements
(even further complex sample preparation is required for the IRMS). Hence, past
and ongoing research targets the development of field deployable instruments for
measuring stable water isotopes at high temporal frequencies. While recent studies have
demonstrated that laser-based instruments may be taken to the field [4, 5], their size and
power consumption still restrict their use to sites equipped with mains power or
generators. Here, we present progress on the development of a field portable mass
spectrometer (FieldSpec) for direct high frequency measurements of δ2H and δ18O ratios
in water. The FieldSpec instrument is based upon the use of a double focusing
magnetic sector mass spectrometer in combination with an electron impact ion
source and a membrane dual inlet system. The instrument directly collects liquid
water samples in the field, which are then converted into water vapour before being
injected into the mass spectrometer for the stable isotope analysis. δ2H and δ18O are
derived from the measured mass spectra. All the components are arranged in a
vacuum case having a suit case type dimension with portable electronics and battery.
Proof-of-concept experiments have been carried out to characterize the instrument. The
results show that the FieldSpec instrument has good linearity (R2 = 0.99). The
reproducibility of the instrument ranges between 1 and 4 ‰ for δ2H and between 0.1 and
0.4 ‰ for δ18O isotopic ratio measurements. A measurement frequency of less
than 60 minutes per sample has been achieved. We intend to further increase the
measurement frequency in the near future. In this presentation, we will describe
the instrument, present experimental data reflecting its performance and discuss
applications.
[1] de Groot, P.A., 2004. Handbook of Stable Isotope Analytical Techniques, Vol.1.
Elsevier, Amsterdam, 1234 pp
[2] Lis, G., Wassenaar, L.I., Hendry, M.J., 2008. Analytical Chemistry 80 (1),
287-293.
[3] Brand, W.A., Geilmann, H., Crosson, E.R., Rella, C.W., 2009. Rapid Communications
in Mass Spectrometry 23, 1879-1884.
[4] Berman, E.S.F., Gupta, M., Gabrielli, C., Garland, T., McDonnell, J.J., 2009. Water
Resources Research 45 W1020, 1-7.
[5] Munksgaard, N.C., Wurster, C.M., Bird, M.I., 2011. Rapid Communication Mass
Spectrometry 25, 3706-3712. |
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