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| Titel |
A gas chromatographic instrument for measurement of hydrogen cyanide in the lower atmosphere |
| VerfasserIn |
J. L. Ambrose, Y. Zhou, K. Haase, H. R. Mayne, R. Talbot, B. C. Sive |
| 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 ; 5, no. 6 ; Nr. 5, no. 6 (2012-06-01), S.1229-1240 |
| Datensatznummer |
250002962
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| Publikation (Nr.) |
 copernicus.org/amt-5-1229-2012.pdf |
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| Zusammenfassung |
| A gas-chromatographic (GC) instrument was developed for measuring hydrogen
cyanide (HCN) in the lower atmosphere. The main features of the instrument
are (1) a cryogen-free cooler for sample dehumidification and enrichment,
(2) a porous polymer PLOT column for analyte separation, (3) a flame
thermionic detector (FTD) for sensitive and selective detection, and (4) a
dynamic dilution system for calibration. We deployed the instrument for a
∼4 month period from January–June, 2010 at the AIRMAP atmospheric
monitoring station Thompson Farm 2 (THF2) in rural Durham, NH. A subset of
measurements made during 3–31 March is presented here with a detailed
description of the instrument features and performance characteristics. The
temporal resolution of the measurements was ~20 min, with a 75 s
sample capture time. The 1σ measurement precision was <10% and
the instrument response linearity was excellent on a calibration scale of
0.10–0.75 ppbv (±5%). The estimated method detection limit (MDL)
and accuracy were 0.021 ppbv and 15%, respectively. From 3–31 March
2010, ambient HCN mixing ratios ranged from 0.15–1.0 ppbv (±15%), with a mean value of 0.36 ± 0.16 ppbv (1σ). The
approximate mean background HCN mixing ratio of 0.20 ± 0.04 ppbv appeared
to agree well with tropospheric column measurements reported previously. The
GC-FTD HCN measurements were strongly correlated with acetonitrile
(CH3CN) measured concurrently with a proton transfer-reaction mass
spectrometer (PTR-MS), as anticipated given our understanding that the
nitriles share a common primary biomass burning source to the global
atmosphere. The nitriles were overall only weakly correlated with carbon
monoxide (CO), which is reasonable considering the greater diversity of
sources for CO. However, strong correlations with CO were observed on
several nights under stable atmospheric conditions and suggest regional
combustion-based sources for the nitriles. These results demonstrate that
the GC-FTD instrument is capable of making long term, in-situ measurements
of HCN in the lower atmosphere. To date, similar measurements have not been
performed, yet they are critically needed to (1) better evaluate the
regional scale distribution of HCN in the atmosphere and (2) discern the
influence of biomass burning on surface air composition in remote regions. |
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