Publication

Summary

As part of an overall plan to mediate contaminated sediments in the Oslo Harbor, dredging inn shallow areas and disposal at 70 m depth were performed. To document to which degree the work has been a benefit to the environment and/or caused spreading of contaminants to organisms a monitoring program was set up in order to collect data on contaminates both in the short and a long term. In this report we collocate results from sampling in 2013 with the results from previous monitoring (2006-2010). The results included pollutant levels in mussels (harbor area, landfill area, Paddehavet, Bygdøynes and Lysaker/Bestumkilen), fish (Bekkelagsbassenget and Frognerkilen) and in deepwater shrimps (Steilene area). Parts of the study area (e.g. harbor) has urban character and is exposed to diffuse, complex/random and partly natural inputs from land and air It has also been implemented nationwide general measures against the use and discharges of pollutants. It has therefore been difficult to firmly link the observed changes to the implemented measures. The analyzed species have different lifestyles, feeding behaviour and occur in various parts of the environment, and are therefore exposed to different types and degrees of contaminants. Pollutant concentrations were in many cases relatively low at the start of the monitoring. One should therefore be cautious in interpreting changes in pollutant concentrations in organisms when these levels do not clearly exceed background concentrations. In a situation where the concentrations are low both before and after the dredging, the differences are of less importance for assessing the effect of the measure...