The occurrence and sources of microplastics to Arctic and sub-Arctic beaches: human influence on local microplastic hotspots

Plastic pollution, and in particular, microplastic pollution, is a global environmental concern particularly in marine ecosystems. The small size of these particles (< 5 mm) means they are prone to ingestion and accumulation by organisms across all trophic levels. Beaches are situated on the transition between the terrestrial and oceanic ecosystems, an important habitat for many species, and have long been known to be sinks of other environmental pollutants. However, until recently their importance as sinks for microplastics and the sources involved were relatively unknown. This study investigates the extent and likely sources of microplastic pollution on beaches in Arctic and sub-Arctic regions, focusing on Svalbard and Iceland. Sediments on beaches at four sites in Svalbard and eleven in Iceland were sampled for microplastics. Subsequent laboratory analyses for microplastic particle ID, size, type, and polymer (using micro-FTIR) was then carried out to estimate abundance and potential uses of the microplastics identified. Statistical analyses of these results, in conjunction with environmental and geographical data, were conducted to identify patterns and potential sources. The results revealed significant variability in microplastic quantity, types, and polymers across all locations. Sites with the lowest microplastic concentrations were situated in the most remote areas, while those with the highest concentrations were in proximity to areas with intense human activities or higher population densities. Statistical analyses showed a clear relationship between observed data and the proximity to human activities/inhabitation, with environmental conditions such as wind direction and currents also playing a significant contributory role. These findings suggest that the lower microplastic concentrations found in remote areas are background contamination from ocean delivered from more distant densely inhabited regions (notably Western Europe), with the high contamination hotspots linked to local activities. These findings underscore the heightened impact of local human factors in driving elevated microplastic pollution in beach sediments over oceanic controls in remote yet inhabited Arctic and subarctic locations.