The chemical composition of particles collected at Alert, Northwest Territories, Canada, show strong, persistent seasonal variations. In a previous study, a 2-way/3-way mixed factor model was performed on the weekly average concentrations of 24 aerosol components measured over the period from 1980 to 1991. The Multilinear Engine (ME), a new mathematical technique, was used to obtain the solution. The two modes of the 2-way model consist of the source composition profiles and mass contributions over the 11 yr, while for the three modes of the 3-way model, source profiles, mass contributions variations over the weeks within a year, and the year-to-year variation over the 11 yr within the measurement period. Five 2-way and two 3-way factors were found to provide a good fit to the data and were easily interpreted. In this investigation, potential source contribution function (PSCF) analysis was applied to the source contributions derived from the ME analysis by incorporating meteorological information in the form of 5-d air parcel back trajectories. The potential locations and/or the preferred pathways of these possible sources were then determined by the PSCF analysis. (C) 1999 Elsevier Science Ltd. All rights reserved.
The results of the inorganic and organic analyses of aerosol samples collected on the east and west sides of Hong Kong during a dust episode (9–10 May 1996) are reported. The origin of the dust was traced to Northern China. The dust reached Hong Kong by way of the East China Sea. The characteristics of the inorganic elements and organic compounds were quite different from the non-episodic samples collected on 1–2 April 1996, EPD (Environmental Protection Department, Special Administrative Region, Hong Kong, China) results for April–May 1994, and our early studies (Zheng et al., 1997. Atmospheric Environment 31(2), 227–237.). Results from X-ray spectrometry showed pronounced increase in the relative abundance of Al, Fe, Ca, S and Cl in the dust samples compared to the non-episodic samples. The high abundance of Cl in the dust samples suggested the aerosols experienced long-range transport by way of the sea. ICP-MS analysis revealed higher concentrations of Fe, Ca, S and Pb in the episodic samples relative to the values measured during April–May 1994 by EPD. The high Ca content in the soil samples is a characteristic of northern Chinese crustal material (Liu et al., 1985). Hong Kong aerosols are characterized by high octadecenoic acid concentration due to heavy urbanization and Chinese-style stir-fry cooking. A much lower C18:1/C18:0 ratio was found in the episodic samples, however, suggesting the aerosols were transported from a long distance. The high ratio of ⩾C20/