Comparison of atmospheric nitrous acid measurements by annular denuder and differential optical absorption systems |
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| Institution: | 1. Air and Industrial Hygiene Laboratory, California Department of Health Services, 2151 Berkeley, Way, Berkeley, CA 94704-9980 U.S.A.;2. Statewide Air Pollution Research Center, University of California, Riverside, CA 92521-0312, U.S.A.;1. Laboratory of Applied and Environmental Chemistry, Mohammed first University, Oujda, Morocco;2. Department of Chemistry, Hashemite University, P.O. Box 150459, Zarqa 13115, Jordan;3. Higher Institute of Nursing and Health Professions techniques, Oujda, Morocco;4. CRMEF Oriental, Centre Régional des Métiers de l''Education et de Formation Oujda, Morocco;1. School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, China;2. State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China;1. Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, UK;2. Escuela de Ingenierías Industriales, University of Málaga, 29071 Málaga, Spain |
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| Abstract: | As part of the Southern California Air Quality Study (SCAQS), nitrous acid (HONO) measurements were made at Long Beach, CA during the period 11 November–12 December 1987, using two distinctly different techniqes. One of these, the annular denuder method (ADM), used two denuders in tandem, coated with an alkaline medium to obtain 4- or 6-h integrated measurements. A small FEP Tefloncoated glass cyclone preceded the denuders to exclude coarse particles while minimizing loss or artifactual formation of HONO. Nitrite recoveries from the rear denuder were used to correct for sampling artifacts. In the second method, 15 min average HONO concentrations were measured with a differential optical absorption spectrometer (DOAS) coupled to a 25 m basepath, open multiple reflection system operated at a total optical path of 800 m. Period-averaged HONO concentrations from the two techniques were highly correlated (r = 0.94), with DOAS results averaging about 10% higher. However, ADM results were biased high at low HONO concentrations. HONO and NO concentrations showed a significant, positive correlation (r = 0.8), consistent with a common emission source (e.g. auto exhaust) for the two pollutants. |
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