Characterisation of solid airborne particles in urban snow deposits from Ljubljana by means of SEM/EDS

摘要

The main objective of this study was to identify and characterise solid airborne particles deposited in snow of the Ljubljana urban area over a period of 6 days, according to their morphology and chemical composition and to assess their source and genesis by means of scanning electron microscope coupled with energy dispersive X-ray spectrometer (SEM/EDS). This method enables the characterisation of submicroscopic (crystalline and amorphous) particles, present in very small quantities. Two snow samples were collected and analysed. Spherical particles, irregularly shaped fragments and agglomerates were identified according to their morphology. Geogenic and technogenic sources were assessed by considering their chemical composition and morphology. Geogenic particles are represented mostly by irregular mineral fragments of quartz, zircon and clay minerals. Technogenic particles are mostly spherically shaped carbonaceous particles, originating from combustion of coal or liquid fuel and spherical heavy metal-bearing particles, emanating from high-temperature industrial combustion and steel-melting processes. Irregular technogenic particles emanate mostly from incomplete coal combustion and road traffic emissions. Comparison of treated samples showed no significant differences in particles according to their origin. It can be concluded that the sampling location had no important influence on the distribution of particles by their origin.