Environmental monitoring and updated risk assessment with emphasis on PAH of the marine environment close to Elkem in Kristiansand in 2013

Sammendrag

Elkem Carbon AS and Elkem Solar AS are conducting a monitoring program in the Kristiansand fjord near their factories. This program supplements the authorities overall monitoring and surveillance programme in the Kristiansand fjord. In 2013, samples of the water masses, blue mussels, sediments and ecological status of the soft bottom fauna were investigated and a risk assessment study of the contaminated sediments was performed. No systematic changes in metal or PAH concentrations in the water masses over the three-year monitoring period could be detected. Metal content in mussels was generally low to slightly elevated, however PAH content in mussels was elevated. Contaminant concentrations were high in the Elkem harbour sediments. The sediment contaminant concentrations were used in a risk assessment. Calculations gave a transport of approx. 3 kg PAH annually from the sediments. The directed discharges of PAH with process water is now strongly reduced to approx. 10 kg/yr. The contaminated sediments represent a calculated risk for sediment-living organisms and to humans based on a lifelong intake of seafood from the area. The latter is not necessarily realistic since fishing in the area hardly occurs and PAH do not accumulate in fish flesh. The quality of the benthic fauna in the Fiskåbukta has improved significantly over the years and might have reached a status as good as can be expected in a mulitisource, urbanized area.