Latitudinal patterns of microplastic contamination in remote areas

Microplastics (MPs) have been detected in a wide array of remote terrestrial areas. Analysing the occurrence of MPs in remote areas is paramount to understand their transport and deposition patterns. Despite the growing body of publications on this topic, studies are often spatially restricted. This limits assessments of global patterns in MPs distribution. Glaciers are landscape features without substantial MPs local inputs, which allows the evaluation of transport and deposition mechanisms. To fill this gap, we gathered 57 samples of supraglacial debris from 9 glaciers, ranging in latitude from 46 degrees S to 78 degrees N. MPs contamination was studied in terms of concentration, shape, size, and polymeric composition, observing significant variations with latitude for all considered parameters. The same held true when considering all anthropogenic particles (APs), including natural polymers. No single polymer was so common to be detected on all glaciers, suggesting atmospheric transport as the main driver of MPs contamination, possibly showing consistent global patterns. Presence of human modified environments in the areas surrounding the glaciers affected MPs size and composition. Detecting latitudinal trends is fundamental for constraining the atmospheric limb of the global plastic cycle and modelling MPs deposition. Since MPs can release toxic additives and pigments into the environment, studies on their distribution can help assess contamination loads and hazards at a global scale.