Comprehensive characterization of aerosols in a subtropical urban atmosphere: particle size distribution and correlation with gaseous pollutants

This paper presents results of two years of monitoring and research on urban particulates with a focus on submicrometer particles, conducted as a part of an ongoing program on comprehensive characterization of fine airborne particulates and their effect on environmental and human exposures. A large number of data has been collected by the Air Monitoring and Research Station operating in the centre of the subtropical city of Brisbane. The Station is equipped in instrumentation for measurements of particle size distributions in submicrometer and supermicrometer ranges in addition to the standard instrumentation for monitoring of the criteria pollutants (PM10, ozone, sulphur dioxide, nitrogen oxides and carbon monoxide). The focus of this paper is on presenting results related to characterization of particle size distribution and concentration trends in the study period, correlation between particle characteristics measured by different instruments, correlation between particle and gaseous data and preliminary conclusions on source characteristics and source contribution for the investigated area. The average submicrometer particulate concentration in the study period was 7.4×103 particles cm-3, and the average number median diameter was 40 nm. The best correlated data are those for submicrometer particles and carbon monoxide and nitrogen oxides, suggesting the same source type. The lack of correlation between submicrometer and supermicrometer particle concentration data implies different sources for particles in these two ranges. Particle spectral analysis and correlation with gaseous data, indicate that motor vehicle emissions constitute the main source of ultrafine particles in the study area.