Temporal and spatial trends in microplastic pollution in Svalbard coastal waters

Abstract

The project investigated the drivers of floating microplastic (MP) pollution in the coastal waters of Isfjorden, Svalbard, from 2021 to 2024. This multi-year timeseries analysis assessed spatial patterns and interannual variability to distinguish between local and distant pollution sources. Results consistently identified a strong spatial gradient, with the highest MP concentrations in Adventfjorden near Longyearbyen and very low concentrations in uninhabited fjords, confirming local anthropogenic input as a major source. However, no clear temporal trend in overall abundance was found. Instead, annual variability was driven by environmental forcings: wind and surface currents redistributed MPs, creating ephemeral accumulation zones (e.g., Billefjorden, 2024), and high zooplankton abundance was correlated with low surface MP levels, suggesting biologically-mediated removal via aggregation or trophic transfer. The persistent absence of MPs in rivers and meltwater from pristine catchments underscores that natural flows are not a source but can form hydrodynamic barriers. This study concludes that MP pollution in Arctic fjords is a dynamic system governed by the interplay of constant local sources and variable physical-biological processes. The robust dataset provides a critical empirical foundation for developing predictive models to quantify source contributions and forecast risks under future climate scenarios.