Monitoring outside Glencore Nikkelverk AS in Kristiansandsfjord in 2016. Investigations of sediment material in Hanneviksbukta using sediment traps.

Summary

NIVA has carried out monitoring of sediment particles using sediment traps outside the harbour of Glencore Nikkelverk AS in Kristiansandfjord. The traps were deployed from 7 August 2015 to 17 March 2016, corresponding to seven months and 10 days, or 223 days. The aim was to quantify the pollutant fluxes to the seabed and concentrations of metals and dioxins in Hannevika outside the harbour of Glencore Nikkelverk AS. The sediment material in the traps reflect discharges to water, hydrographical (from land, primary production in the water column, flow conditions etc.) and physical conditions during the deployment period. Sediment material may also originate from resuspension from the seabed and from other sources than discharges from the industry. The reported discharges from Glencore Nikkelverk AS or other known sources can not entirely explain the pollutant fluxes of metals and dioxins to the seabed. The 2009- and 2016-results indicate that other processes such as resuspension, transport and sedimentation of particles from Hannevika or surrounding areas, or inputs from unknown or diffuse sources can not be disregarded. However, this study does not provide a basis for assessing their significance. This investigation did not confirm that there was an improvement of the sediments since 2009 through natural processes. The study indicated that good chemical status may be difficult to achieve.