Geochemical characteristics of solid particles deposited on experimental plots established for traffic pollution monitoring in different countries

Abstract

The main aim of this research was to identify the mineralogical, morphological, and chemical characteristics of solid particles emitted by vehicular traffic and deposited on special monitoring plots located on the roadside of five countries with different climatic conditions and traffic structure. Within 24 months of exposure, the composition of the matrix used at the monitoring plots changed. Percentage quartz content decreased in all locations, and due to the input from local sources, the share of other mineral phases increased. In some locations, an increase in the share of mineral phases associated with local parent rock and soil erosion was noted (e.g. Helsinki, Böblingen). In other places, material associated with abrasion of the road surface was characteristic (e.g. Gliwice, Opole). The composition of pollutants accumulated at all the monitoring plots was varied, however the common feature was the presence of technogenic magnetic particles in the matrix after exposure. Analyses showed that numerous irregular, angular particles of iron oxides with porous surface, which are carriers for a number of metals and metalloids were present in the samples. Angular iron oxides containing zinc, chromium, and copper are usually considered as non-exhaust traffic emissions. Another type of iron oxides particles found in the samples were magnetic spherules related to exhaust emissions (smaller spherules, < 20 μm). Study of results confirmed the effectiveness of the testing method for roadside pollution monitoring related to currently emitted solid particles accumulated on matrix of known mineral composition.