Meltwater chemistry and characteristics of particulate matter deposited in snow as indicators of anthropogenic influences in an urban area.

A geochemical study of snow from the industrial town of Maribor (Slovenia) was performed. Concentrations of 61 elements in meltwater were determined, and a detailed semi-quantitative and qualitative analysis of individual PTE-bearing particles deposited in snow was performed with SEM/EDS. The physico-chemical characteristics of meltwater reflect the influence of winter road maintenance (high electrical conductivity and high Ca and Na concentrations close to the main roads) and industrial activities. Particulate matter deposited in snow consists mainly of carbonates and silicates, followed by carbon-rich particles and PTE-bearing particles. A higher abundance of PTE-bearing particles is typical for the industrial zones. The size, morphology and chemical composition of 4415 PTE-bearing particles were studied. They were organised into nine groups based on their characteristics. The majority were assigned to the group of Fe-oxides, which includes mostly angular particles of unidentified origin. Several groups of particles of anthropogenic origin were determined, mainly from industrial metal-processing activities. These particles include spherical Fe-oxides, Fe-alloys, other metal alloys and spherical Si-particles. Spherical Fe-oxides are typical for the Tezno industrial zone, while Fe-alloys, namely Fe-Cr (Cu, Mn, Ni) shavings and other metal alloys (Cu-Zn (Cl, Fe) shavings) are typical for the Melje industrial zone. The presence of naturally occurring mineral particles (e.g. zircon, ilmenite, monazite) reflects the influence of natural/geogenic sources on the composition of particulate matter deposited in snow. The presented study confirmed that snow is a very promising medium for the geochemical study of urban environments, especially for the identification of anthropogenic sources of particulate matter.