Paul Whitehead and colleagues have published a new study of microplastics in the Thames River, UK. This is an exciting paper for a number of reasons. It is one of the first realistic applications of a riverine water quality model to the problem of microplastic pollution and it is the first published paper using the INCA-Microplastics model with real data. This study also presents one of the first examples of an INCA model implemented using the open source MOBIUS framework.
Microplastic pollution of surface waters is an issue of increasing societal concern. Plastics and microplastics are ubiquitous in freshwater ecosystems. Understanding the transport and distribution of microplastics in river systems is key to assessing impacts. Modelling the main flow dynamics, mixing, sedimentation and resuspension processes is essential for an understanding of the transport processes. Professor Whitehead and colleagues applied INCA-Microplastics to the whole of the freshwater catchment of the River Thames, UK, to evaluate inputs, loads and concentrations along the river system. They calibrated the model against UK water industry measurements of microplastics in effluent discharges and sewage sludge. In their simulation, they showed significant increases in microplastic loads moving along the river system, with rising concentrations in downstream reaches and increasing deposition to the riverbed. The paper presents an assessment of potential impacts on aquatic ecosystems and a review of policy implications.