Utvärdering av tungmetaller i ägg från Mellanskarv (Phalacrocorax carbo sinensis) från ön Gråen, Landskrona hamn, Skåne

Sammanfattning: In compliance with the environmental objective Non-toxic Environment, the city of Landskrona town and the County Administrative Board of Scania collected and analyzed Cormorant eggs (Phalacrocorax carbo sinensis) from the island Gråen outside Landskrona for various pollutants. This study aims to investigate whether measured concentrations of mercury (Hg), Zinc (Zn), and Copper (Cu) exceed those from other locations or environmental quality standards (EQS). Monitoring data of bird eggs from the Baltic Sea is scarce and EQS for metals in bird eggs do not exist. Thus, this study also investigates whether it is possible to convert concentrations in Cormorant eggs to concentrations in other matrices such as water, Cw, and their prey, Cprey, and compare these to EQS for water and biota. The external stakeholders were also interested in knowing whether monitoring Cormorant eggs is worth continuing with. Cw and Cprey were calculated using known equations for Bioconcentration factors and Biomagnification factor. In order to obtain the potential risk of Cw and Cprey exceeding EQS, a computer based model, @Risk, was used. When comparing converted levels from Cormorant eggs with EQS for coastal water and biota, the results indicate that Landskrona harbour has elevated concentrations of mercury. Additional monitoring of mercury using bird eggs from the Baltic Sea is needed in order to secure proper spatial comparisons. However, when monitoring data is scarce, used method of converting metal concentrations in eggs to another matrix for comparisons with EQS, is functional. Continued monitoring of zinc and copper using Cormorant eggs is only recommended for obtaining temporal differences. Using Cormorant eggs for environmental monitoring can be problematic since they are migratory and may have accumulated heavy metals from the location they move to during Swedish winter. Eggs from non-migratory bird are therefore recommended for further monitoring of heavy metals outside Landskrona harbour.