Enhanced heavy metal discharges to marine deposits in glacial bays of two Arctic fjords (Hornsund and Kongsfjorden)

Climate change is transforming Arctic ecosystems in ways that are influencing the transport and accumulation of contaminants. The spatial and temporal variability of heavy metal distribution was studied in two Spitsbergen fjords – Kongsfjorden and Hornsund. Sediment cores from five stations in Kongsfjorden and six in Hornsund were collected in 2018–2019 and used for measurement of heavy metal concentrations (Hg, Pb, Cd, Cu, and Zn). Sediment layers were dated by the ²¹⁰Pb method to reveal the history of contamination. Isotopic lead composition was used to study sources of Pb. Loads of heavy metals to fjord deposits were calculated based on mass sediment accumulation rates. The heavy metal loads varied spatially and reached ranged 0.3 mg m⁻² yr⁻¹ for Hg, 57.6 mg m⁻² yr⁻¹ for Pb, 0.5 mg m⁻² yr⁻¹ for Cd, 101 mg m⁻² yr⁻¹ for Cu, and 117 mg m⁻² yr⁻¹ for Zn. Heavy metal discharge from the glaciers to the glacial bays were much higher compared to discharge in central and outer fjord parts. This may suggest that glaciers can be important secondary sources of pollutants to fjords.