Glacial bay as a local hot spot for retention and accumulation of heavy metals transported with glacier meltwater (Hornsund, Svalbard

In this study, we aim to understand the influence of an underwater sill on the fate of suspended particulate material (SPM) discharged by a melting tidewater glacier in an Arctic glacial bay. We examined the potential significance of SPM retention for the bay’s environment by analysing the fate of heavy metals introduced by glacier meltwater. Semi-enclosed bays with sills can not only limit water exchange but also act as effective traps for SPM and, consequently, for components, e.g., pollutants adsorbed onto these particles. Enhanced deposition of particulate pollutants can locally pose a threat to the ecosystem. We focus on Hansbukta, a glacial bay in Hornsund Fjord (Svalbard) that receives freshwater from the rapidly melting Hansbreen, a tidewater glacier. We analysed suspended particulate matter (SPM) concentrations and associated heavy metal content in six ablation seasons (2015–2020). Our results reveal seasonal variability in SPM and metal concentrations. In most months, over half of the analysed elements discharged with glacier meltwater remain in the bay. It was concluded that Hansbukta, which is isolated from the main fjord basin by an underwater sill, acts as a trap for metals and possibly other pollutants