Processes driving heavy metal distribution in the seawater of an Arctic fjord (Hornsund, southern Spitsbergen).

The temporal and spatial variability of heavy metal distribution was studied in an Arctic fjord (Hornsund, Spitsbergen). Seawater from 8 sampling stations and 3 sampling depths was collected in 6 successive months and used for measurement of dissolved and particulate heavy metal concentrations. Salinity and temperature profiles were determined prior to sampling and water masses were classified according to their properties. Isotopic lead composition (206Pb/207Pb and 206Pb/208Pb ratios) was studied to find the sources of Pb to the fjord seawater. Hornsund seawater was contaminated with the studied heavy metals (particularly during the summer months). Extremely high contamination with Cd was measured (dissolved up to 488 ng·L-1, while particulate up to 303 ng·L-1), which is most probably connected to high atmospheric deposition. Depending on the season and the region, metal distribution was modified by glacier meltwater and surface run-off discharges, melting of fast ice, direct atmospheric deposition, transport of sea salt, intrusion of Atlantic water, sediment re-suspension, as well as re-mobilization.