Multivariate Statistical Evaluation of the Chemical Composition of Fine Particles : A Case Study

Monitoring and assessment of the physical and chemical constituents of airborne pollutants are now common features of the efforts of Queensland Environmental Protection Agency (EPA) to protect the public from the adverse effects of ambient air pollution. This paper describes the evaluation of the profiles of the 21 chemical constituents of 24-hourly integrated fine particle samples collected by EPA at Rocklea from 1995 to 2003. Because of the multivariate nature of the data, they were subjected to the multi-criteria decision making method, Preference Ranking Organisation Method for Enrichment Evaluation (PROMETHEE) and Principal Component Analysis. The PROMETHEE results indicated that the quality of the fine particulate constituents at the site decreased in the order 1995 >1997 >1996 >1998 >2002 >2000 > 2003 > 2001 > 1999. The most important constituents influencing the ranking included the elemental carbon, sulfur, lead, bromine, vanadium, and chromium contents of the samples. Such multi-criteria ranking provides information that can assist the formulation and prioritization of mitigating measures. For example, the phasing out of leaded fuels contributed significantly to the lowering of Pb and Br in the samples. On the other hand, Principal Component Analysis showed that the major constituents clustered into groups with compositional profiles which suggested that the main sources of the particles were airborne soil, combustion activities (vehicular emission and vegetative burning), industrial emissions, secondary aerosols and sea salt. Correlation with other pollutants and meteorological data concurrently measured at the site provided further insights into the sources of the fine particles