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Flask sample measurements for CO2, CH4 and CO using cavity ring-down spectrometry.
- Source :
- Atmospheric Measurement Techniques Discussions; 2013, Vol. 6 Issue 4, p7633-7657, 25p
- Publication Year :
- 2013
-
Abstract
- In recent years, cavity ring-down spectrometry (CRDS) has been demonstrated to be a highly sensitive, stable and fast analytical technique for real-time in situ measurements of greenhouse gases. In this study, we propose the technique (which we call flask-CRDS) of analyzing whole air flask samples for CO<subscript>2</subscript>, CH<subscript>4</subscript> and CO using a custom gas manifold designed to connect to a CRDS analyzer. Extremely stable measurements of these gases can be achieved over a large pressure range in the flask, from 175 to 760 Torr. The wide pressure range is conducive to flask sample measurement in three ways: (1) flask samples can be collected in low-pressure environments (e.g. high-altitude locations); (2) flask samples can be first analyzed for other trace gases with the remaining low-pressure sample for CRDS analysis of CO<subscript>2</subscript>, CH<subscript>4</subscript> and CO; and (3) flask samples can be archived and re-analyzed for validation. The repeatability of this method (1α of 0.07 ppm for CO<subscript>2</subscript>, 0.4 ppb for CH<subscript>4</subscript>, and 0.5 ppb for CO) was assessed by analyzing five canisters filled with the same air sample to a pressure of 200 Torr. An inter-comparison of the flask-CRDS data with in-situ CRDS measurements at a high-altitude mountain baseline station revealed excellent agreement, with differences of 0.10±0.09 ppm (1α) for CO<subscript>2</subscript> and 0.9±1.0 ppb for CH<subscript>4</subscript>. This study demonstrated that the flask-CRDS method was not only simple to build and operate but could also perform highly accurate and precise measurements of atmospheric CO<subscript>2</subscript>, CH<subscript>4</subscript> and CO in flask samples. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 18678610
- Volume :
- 6
- Issue :
- 4
- Database :
- Complementary Index
- Journal :
- Atmospheric Measurement Techniques Discussions
- Publication Type :
- Academic Journal
- Accession number :
- 91631163
- Full Text :
- https://doi.org/10.5194/amtd-6-7633-2013