| Autor: |
Hsunling Bai1 hlbai@green.ev.nctu.edu.tw, Heng-Yi Wen, J. Pierre1 |
| Předmět: |
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| Zdroj: |
Journal of the Air & Waste Management Association (Air & Waste Management Association). Jan2000, Vol. 50 Issue 1, p125-130. 6p. 1 Diagram, 3 Charts, 3 Graphs. |
| Abstrakt: |
Experiments on different annular denuder system (ADS) arrangements for sampling nitrous acid (HNO[sub2]) and nitric acid (HNO[sub 3]) gases were conducted in this study to evaluate their sampling artifacts. The evaluation basis is the one that employed one sodium chloride denuder for sampling HNO[sub3] gas and two sodium carbonate (Na[sub2]CO[sub3]) denuders for sampling HNO[sub2] gas, which is a commonly employed ADS arrangement in many field applications in the United States. A field study was conducted in Hsinchu, Taiwan, and the results indicated that this ADS arrangement may yield over 80% relative errors for HNO[sub3] gas. It also showed that the relative errors for HNO[sub2] gas can be less than 10% as sampled with only one Na[sub2]CO[sub3] denuder. This is attributed to the fact that the ambient HNO[sub3] concentration measured in this study was relatively low while the HNO[sub2] concentration was high, as compared to typical concentrations of these two gases measured in the United States. The sampling error of HNO[sub3] gas may be due to high concentrations of N-containing interfering species present in Taiwan's atmosphere. Because the relative sampling errors of HNO[sub3] and HNO[sub2] gases depend mainly on their concentrations in the atmosphere as well as concentrations caused by interfering species, the risk for high error while measuring low HNO[sub2] concentrations by only one Na[sub2]CO[sub3] denuder is also possible. As a result, it is suggested that pretests are necessary to evaluate possible sources and degrees of sampling errors before field sampling of HNO[sub2] and HNO[sub3] gases. The sampling errors of these two gases can, therefore, be minimized with a better arrangement of the ADS. [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
| Externí odkaz: |
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