Glass microspheres as a potential indicator of the Anthropocene: A first study in an urban environment

Glass microspheres are spherical glass particles that have many applications including composite polymer material technology, medicine, analytical chemistry, abrasive blasting, paints, and coatings. They are widely used in the production of road and pavement marking materials, such as traffic paints, thermoplastics, and preformed markings. The abundance of glass microspheres in terrestrial deposits and possibly in marine sediments, as well as their physical and chemical stability, would make them a good indicator of the Anthropocene in geologic records. The Anthropocene as an epoch of the geologic timescale should be identified by the presence of specific signals in strata formed during this interval. An ideal geologic indicator of the Anthropocene should be ubiquitous in different environmental settings and should have a strong preservation potential in future strata. In this study, road dust and river sediment samples were collected in the city of Kielce (south-central Poland) and examined for the presence of glass microspheres. A large number of microspheres in the road dust samples (800-2700 microspheres/kg) suggests that the microspheres released by degradation of traffic paints may be effectively transported from the road dust to river sediments. This is evidenced by the highest number of glass microspheres found in a river sediment sample collected near street stormwater discharge (1500-9600 microspheres/kg). The occurrence of glass microspheres in the river sediments collected at about 500 m from the road where reflective traffic paints are used (200-500 microspheres/kg) suggests that these are likely to be subjected to fluvial transport.