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ATMOSPHERIC ACIDITY MEASUREMENTS DURING THE LAKE MICHIGAN URBAN AIR TOXICS STUDY
Citation:
Lamborg, C., G. Keeler, AND G. Evans. ATMOSPHERIC ACIDITY MEASUREMENTS DURING THE LAKE MICHIGAN URBAN AIR TOXICS STUDY. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-92/250 (NTIS PB93121069).
Description:
During the summer of 1991, as part of the Lake Michigan Urban Air Toxics Study (LMUATS), measurements of reactive gases and fine fraction and size-fractionated acidic aerosols were taken at two sites (South Haven, MI and aboard the research vessel, R/V Laurentian). he fine fraction aerosol samples were collected using an annular denuder system (ADS) which allowed quantification of acidic and basic gases, as well as inorganic ions in the fine particle fraction (<2.5 um). he size-fractionated data were obtained using a six stage micro-orifice impactor (MOI) equipped with ammonia-scrubbing denuders. he ADS aerosol results showed extreme episodic behavior which correlated well with air mass transport from the southwest. he maximum concentrations observed in South Haven with overlake transport from the southwest were 241 nmol/m3 for aerosol strong acidity (H+) and 3.8 ppb for nitric acid (HN03). hese elevated acid levels were accompanied by hourly maximum 03 concentrations of 128 and 153 ppb, respectively. evels at South Haven and aboard the R/V Laurentian were very similar for most of the species measured. ize-fractionated particulate mass results also compared well for most species, and showed a typical size-dependent behavior.
