Bedform morphology changes due to plastic pollution: Preliminary observations and potential implications

The pervasive presence of plastics in our planet’s water bodies has mostly received attention due to its impacts on animal and human health, and their environments. However plastic pollution is also an important abiotic component of riverbeds as it interacts with physical processes, thereby affecting the mechanics of sediment transport. We conducted experiments in a recirculating flume, where we added a low concentration of plastics of different properties (0.12% by mass) and observed its interactions with the bed. Our observation suggest that (i) plastics affect bedform geometries and migration patterns; and (ii) plastics actively change sediment transport mechanics and potentially change local sediment transport modes and budgets. These observations highlight the need for for new sediment transport relations that deal with mixtures composed of materials of different sizes and densities. It is critical to understand such mixtures as the effects of these novel grain-to-grain interactions will compound and scale up to impact catchment-scale dynamics.