The Norwegian Water Column Monitoring programme 2021: Assessing the impacts of Ekofisk and Eldfisk offshore oil and gas installations on the marine environment

The Norwegian offshore Water Column Monitoring (WCM) programme investigated the potential effects of Ekofisk and Eldfisk oil and gas installations on the marine environment. Produced water (PW) impacts were assessed in the water column by deploying monitoring stations containing mussels, passive samplers (PSDs), scallops and scientific equipment downstream of the Ekofisk and Eldfisk installations for 6 weeks at 2 depths between March and May 2021 and compared to two reference stations and a day zero group. Chemical and biological effects were measured and a clear relationship between PAH concentration in mussels and proximity to the Ekofisk installation was shown in the 20 m mussels reaching background concentrations in mussels 4000 m downstream. Only low concentrations were found in the Eldfisk mussels and 40 m mussels and scallops showing low exposure to the PW plume. Biological responses in mussels represented a weak response to low PW exposure. In addition, demersal fish were collected from within the Ekofisk safety zone and three regions of the North Sea (Ekofisk region, Egersundbank, Vikingbank). Integrated chemical and biological effects were measured, a relationship between PAH exposure (liver /metabolites) in dab and CYP1A activity (EROD and CYP1A protein), with higher levels in dab populations living in areas of oil and gas activity. Genotoxicity was also observed in cod and dab from the Ekofisk.