June-Sang Siak

Multivariate statistical analyses of air quality data and bacterial mutagenicity data from ambient aerosols

Abstract As part of the 1982 Detroit Summer Air Pollution Study, the relationships between the mutagenicity of ambient aerosols and other air quality components were examined. Thirty-one samples of total suspended particulate matter collected at a site in central Detroit were extracted with dichloromethane and fractionated into 16 fractions using thin layer chromatography. The individual fractions were then examined for mutagenicity by the Ames test using tester strains TA98, TA98NR and TA98DNP6. The results showed that most of the mutagenicity (64%) was contained in four polar fractions, and one polar fraction accounted for 34% of the total activity. Using principal component and multiple linear regression analyses, we examined relationships between the mutagenicity in each fraction and the air quality and meteorological variables. Overall, the measured observables explained about 40% of the mutagenicity variance. A single component containing SO2 emissions was the most important component as it explained 20% of the mutagenicity variance. The component containing motor vehicle emissions explained 13% of the mutagenicity variance. Photochemically-initiated reactions appear to play a minor role as this component explained an insignificant amount of the mutagenicity variance. The liquid water content of the ambient aerosol explained a significant part of the mutagenic variance of several fractions.

Temporal Patterns of Bacterial Mutagenicity on Ambient Aerosols in Southeastern Michigan

The temporal and diurnal patterns of particulate-bound mutagens in the atmosphere were examined for a two-month period in the summer of 1985. Daily PM-10 samples were collected at 0900–2100 and 2100–0900 along with other air quality measurements from a suburban site in southeast Michigan. The paired samples were collected daily in order to examine day/night variations. Each particulate sample was extracted and separated into 16 different fractions based on polarity before Ames tests were conducted on each fraction to determine the bacterial mutagenic activities in TA98 and TA98/DNP6. Other air quality parameters measured included fine particle mass (diameter less than 2.5 μm), sulfate, sulfur dioxide, nitrogen oxides, nitric acid, ozone, carbonaceous aerosols, some trace elements, and pertinent meteorological data. The results show that the four most polar fractions accounted for at least 70% of the mutagenicity. The highest levels of mutagenic activity occurred during two different types of meteorologica...