Towards a holistic approach to the geochemistry of solid inorganic particles in the urban environment.

Airborne particulate matter (PM) has a major impact on the biogeochemical cycles of chemical elements in the urban environment. Anthropogenic-derived PM emissions are the cause of some of the most severe environmental and health problems. The presented study aims to improve our knowledge of PM dynamics by introducing a multi-media, multi-analytical and multi-elemental holistic approach to geochemical studies of inorganic PM in the urban environment. The importance of the holistic approach is highlighted and its application in a case study of Maribor (Slovenia) is presented. The chemical composition and individual particulate characteristics of street, attic and household dust were determined and compared with the characteristics of airborne PM, and PM deposited in snow, together with the chemical composition of the soil. We found that the mineralogical and chemical composition and the individual solid particle characteristics of the studied media differ considerably. Nevertheless, minerals of geogenic origin are present in all media. The highest levels of potentially toxic elements (PTEs) in all media, except household dust, are typical for industrial areas. Street dust primarily reflects the influence of winter road maintenance and industrial activities, while characteristics of household dust are predominantly influenced by indoor activities and properties of dwellings. The comparison of the chemical composition of attic and street dust indicates that emissions of As, Cd, Pb, S and Zn were higher in the past. The characterisation of airborne PM and PM deposited in snow is essential for the identification of the most recent sources of PTE-bearing particles. Several industrial sources and the fate of some particle types in the environment have been determined based on the findings of the SEM/EDS analyses. This study confirms that various environmental media are carriers of diverse geochemical information and highlights the importance of a holistic approach in geochemistry of PM in urban areas.