Apportionment of air pollution sources by receptor models in Hong Kong

The application of a receptor modelling method for the apportionment of air pollution sources in a highly urbanised area has been investigated using trace metals as marker elements in air particulates sampled at five stations in New Territories in Hong Kong. The elemental profile of the coal used for burning, the fly ash obtained after the electrostatic precipitator and the ambient particulates collected at the five sampling sites were determined. The variability is found to be substantial and necessitates the use of factor analysis to identify the source prior to regression analysis for apportionment of the contribution of the various factors identified. Six factors are successfully isolated and their sources identified. Despite a negative loading of the sea aerosol, the mass contributions of other major sources (mg m−3) are estimated as construction work (6.48), automobile/incineration (1.93), wind-blown dust (7.14), coal-fired power plant (4.92) and oil combustion sources (8.15). The use of particle fractionation was found able to resolve earthy and non-natural material, especially at the fine particulate end, and thus provides a method to solve the negative scaling problem encountered during the regression analysis.