Research Projects

Project at a Glance

Project Status: complete

Title: Measurements of NO2, HONO, NO3, HCHO, PAH, nitroarenes and particulate mutagenic activities during the carbonaceous species methods comparison study.

Principal Investigator / Author(s): Roger Atkinson

Contractor: Statewide Air Pollution Research Center, UC Riverside

Contract Number: A5-150-32

Research Program Area: Atmospheric Processes


To allow for methods development and methods intercomparisons prior to the 1987 Southern California Air Quality Study, the California Air Resources Board funded two methods intercomparison studies, one in 1985 at Claremont concerning the measurement of nitrogenous species, and a second at Citrus College, Glendora, during August 1986 dealing principally with measurement methods for organic and carbonaceous species. In the Carbonaceous Species Methods Comparison Study (CSMCS) at Citrus College, Glendora, the Statewide Air Pollution Research Center conducted measurements of the ambient concentrations of several inorganic and organic species. Specifically, the following measurements were made:

Using long pathlength differential optical absorption spectroscopy (DOAS), we measured nitrogen dioxide (N02), nitrous acid (HONO) and formaldehyde (HCHO).

Using long pathlength Fourier infrared (FT-IR) absorption spectroscopy, we measured nitric acid (HNO3 ), ammonia (NH3 ) and HCHO.

Ambient air samples were collected during 12-hr. daytime and 12-hr. nighttime periods onto Tenax solid adsorbent, polyurethane foam plugs and Teflon-impregnated glass fiber filters, and these samples were analyzed for mutagenicity and gas- and particle-associated polycyclic aromatic hydrocarbons (PAH) and nitroarenes.

An extensive data set for the gas-phase concentrations of NO2, HONO, HNO3, HCHO, NH3 and the NO3 radical was obtained (by DOAS and / or FT-IR spectroscopy), during this study period. Significant concentrations of these pollutants were observed, with ambient concentrations of up to approximately 140, 4.5, 30, 20 and 15 parts-per-billion (ppb) for NO2, HONO, HNO3, HCHO and NH3, respectively. A definitive measurement of the time-concentration profile of NO3 radicals was made on only one night during this study, with a peak NO3 radical concentration of 70 parts-per-trillion (ppt) being measured on the night of August 13. The presence of NO3 radicals, at levels < 40 ppt, was observed on the evenings of August 13, 19 and 20.

Ambient particulate organic matter (POM) was collected on a 12-hr. daytime and nighttime sampling period (0800-2000 and 2000-0800 PDT) and was tested for mutagenicity towards Salmonella typhimurium strains TA98 (with and without added S9), TA98NR (-S9) and TA98/1, 8-DNP (-S9). The mutagen densities obtained were consistent with those we have measured previously in the South Coast Air Basin. As also observed previously, the mutagen densities and mutagenic activity of the POM measured in the presence and absence of S9 were essentially indistinguishable, with average mutagen densities (rev m-3) of 33 and 35 towards strain TA98, with and without S9, respectively, and a maximum of 61 rev m-3 (TA98, -S9).

Ambient air was also sampled on filters and solid adsorbents to collect the gas and particle associated PAM and nitroarenes for combined gas chromatography-mass spectrometry analysis. The following PAH and nitroarenes were observed and quantified: naphthalene, 1- and 2-methylnaphthalene, biphenyl, acenaphthene, acenaphthylene, fluorene, phenanthrene, anthracene, dibenzothiophene, fluoranthene, pyrene, benz(a)anthracene, chrysene/triphenylene, benzo(a)pyrene, 1- and 2-nitronaphthalene, 3-nitrobiphenyl, 2-, 3- and 8-nitrofluoranthene and 1- and 2-nitropyrene.


For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893

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