DOAS urban pollution measurements
During July and August of 1990, a differential optical absorption spectrometer (DOAS) made by OPSIS Inc. was used to measure gaseous air pollutants over three separate open paths in Atlanta, GA. Over path 1 (1099 m) and path 2 (1824 m), ozone (O{sub 3}), sulfur dioxide (SO{sub 2}), nitrogen dioxide (NO{sub 2}), nitrous acid (HNO{sub 2}), formaldehyde (HCHO), benzene, toluene, and o-xylene were measured. Nitric oxide (NO) and ammonia (NH{sub 3}) were monitored over path 3 (143 m). The data quality and data capture depended on the compound being measured and the path over which it was measured. Benzene, toluene, and o-xylene concentrations measured over path 2, which crossed over an interstate highway, were higher than concentrations measured over path 1, implicating emissions from vehicles on the highway as a significant source of these compounds. Federal Reference Method (FRM) instruments and a gas chromatograph (GC) were located near the DOAS light receivers and operated concurrently. Correlation coefficients greater than 0.85 were obtained between the DOAS and FRM's for O{sub 3}, NO{sub 2}, and NO; however, there was a difference between the mean values obtained by the two methods for O{sub 3} and NO. Correlation coefficients of about 0.66 were obtained between the DOAS and GC measurements of benzene and o-xylene. However, the correlation coefficient between the DOAS and GC measurements of toluene averaged only 0.15 for the two DOAS measurement paths. The lack of correlation and other factors indicate the possibility of a localized source of toluene near the GC.
- Research Organization:
- Environmental Protection Agency, Research Triangle Park, NC (USA). Atmospheric Research and Exposure Assessment Lab.
- OSTI ID:
- 5737846
- Report Number(s):
- PB-91-176966/XAB; EPA--600/D-91/044
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ABSORPTION SPECTROSCOPY
AIR POLLUTION
AIR POLLUTION MONITORING
ALDEHYDES
ALKYLATED AROMATICS
AMMONIA
AROMATICS
ATLANTA
BENZENE
CHALCOGENIDES
CHEMICAL ANALYSIS
CHROMATOGRAPHY
DEVELOPED COUNTRIES
ECOLOGICAL CONCENTRATION
FEDERAL REGION IV
FORMALDEHYDE
GAS CHROMATOGRAPHY
GEORGIA
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
NITROGEN COMPOUNDS
NITROGEN DIOXIDE
NITROGEN HYDRIDES
NITROGEN OXIDES
NITROUS ACID
NORTH AMERICA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
OZONE
POLLUTION
POLLUTION SOURCES
SEPARATION PROCESSES
SPECTROSCOPY
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
TOLUENE
URBAN AREAS
USA
XYLENES