Long, Xuezhu; (1998) Particulate air pollution in central London: Characterisation, temporal patterns, and source apportionment. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Burkard 7-day volumetric spore trap has been employed in collecting airborne particles in central London. Two different kinds of adhesive tapes, a glycerol/gelatine coated transparent tape and a magic adhesive tape, are installed on a clock-driven drum which moves past the orifice at a speed of 2mm/hour, providing a method of recording airborne particles with time resolution. Individual particles collected during 1200 of the 21st to 1200 of the 28th, Februaiy, 1996, and during 1200 of the 9th to 1200 of the 16th, July, 1996 have been analysed. Morphologic parameters of 21,572 particles collected in February and 10,247 in July were analysed by using an optic microscope. Elemental compositions of 25,301 particles in February and 15,736 in July were analysed by EDS. In elemental analysis, multivariate statistic method, i.e. principal component analysis (PCA), is used to get the structures of these data. Enrichment factor (EF) is used to separate crust elements from non-crust elements. Cluster analysis has been used to group particles into different categories according to the morphologic parameters or elemental composition of individual particles. Cluster analysis of morphological data has revealed that combustion processes related particles dominated particle number in winter and biological particles comprise the largest particle category in summer. Chemical analysis has shown that industrial emissions, earth surface dusts, sea-salt, combustion processes, cement warehouses in the local area and anthropogenic miscellaneous emissions have contributed to airborne particles in central London. But most particles analysed are chemically mixed. Seasonal differences and diurnal variations of particle number, size and categories have been presented. Last, the effects of meteorological conditions on particle characteristics have been briefly examined.

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