Fractionation of Anthropogenic Particles (Microplastics and Microfibers) along a 2200 km Transect of Canadian Sediments

Our research suggests that anthropogenic particles (AP), a suite of contaminant particles that originate from human activities including microplastics and microfibers, can undergo geographic fractionation during long-range transport from populated source regions to remote receptor regions. Assemblages of microplastics, microfibers, and other AP (>125 μm) in surficial sediments spanning a 2200 km transect had the most diverse shapes, colors, and polymer types in populated source regions, as illustrated by the Greater Toronto Area and Laurentian Great Lakes, and were least diverse in remote Hudson Bay and Arctic Ocean samples. We hypothesize that differences in diversity are due to a fractionation process where transport from source regions is controlled predictably by differential AP mobility. Specifically, microfibers consisting of anthropogenic cellulose and polyester were found to accumulate in the remote regions of the Arctic, indicating their mobility, which enables long-range transport, consistent with their higher buoyancy in air and water. Conversely, nonfibrous particles (i.e., fragments, films, foams) settled closer to sources, consistent with lower mobility due to faster settling velocities and the likelihood of fragmentation. As with other contaminants, control measures to mitigate and reduce AP discharges in populated urbanized regions will mitigate AP contamination in the Arctic and other remote areas, particularly for the most highly mobile microfibers.