A step towards microlitter risk assessment: modelling microlitter storage potential of the UK seabed.

Seafloor sediments have been defined as sinks for microplastics in the marine environment and could therefore represent suitable matrices for their long-term monitoring. Previous studies indicated the widespread distribution of microlitter in seafloor sediments for the UK. In the present study, observations from 2017 to 2021 were used to produce a microlitter distribution model (unitless), derived from physical properties of the seabed that are known to drive the storage capacity of microlitter. The predicted distribution model was converted into a geospatial data layer and plotted against additional open access data layers for likely sources of marine litter (e.g. marine structures) as well as data layers for more sensitive features around the UK (e.g. marine protected areas (MPAs)). Visualization of the accumulation zones for microlitter against the different layers allowed the identification of areas potentially at risk from an increased addition of microlitter from various sources (e.g. dredge disposal sites). Identification of potential risks and prioritization for different zones of action would help the development of national and regional monitoring strategies while reducing costs of multi-compartment, larger scale monitoring programmes. Additional observations and targeted monitoring data are needed to link potential sources of accumulations for microplastics with a higher level of certainty.This article is part of the Theo Murphy meeting issue 'Sedimentology of plastics: state of the art and future directions'.