Monitoring for NOAH Langøya AS in the Holmestrandfjord. Investigations of blue mussel and cod in 2017.

Summary

In October 2017, NIVA carried out monitoring of blue mussel and cod in the vicinity of NOAH Langøya AS. This survey is supplementary to the ongoing operational monitoring. Blue mussel was collected from three stations (B3, B4 and the reference station 35A Mølen), and cod was collected nearby Langøya. There were no exceedances for the EU-priority pollutants anthracene, benzo(a)pyrene, fluoranthene, naphthalene and tributyltin (TBT) in mussels or for TBT in cod liver. There were exceedances for the EU-priority pollutant mercury (Hg) in blue mussel at stations B3 and B4, and in the cod fillet. The Hg-concentration (0.022 mg/kg w.w.) at mussel station B4, close to the point of discharge, was close to the EU limit value (0.02 mg/kg w.w.). This led to "no good chemical status” in mussels at stations B3 and B4, and also for cod. The mussels at the reference station 35A Mølen had "good chemical status". There were no exceedances for the water region specific substances benzo(a)anthracene in blue mussel and for triphenyltin (TPhT) in mussels and cod liver. Levels of radionuclides (226Ra) in mussels were higher at station B4 (400±21 mBq/kg w.w.), close to the point of discharge, than at station B3 (75±21 mBq/kg w.w.). The levels at station B3 were higher in 2017 compared to 2016 (18±13 mBq/kg w.w.), but at about the same level as in 2015 (71±11 mBq/kg w.w). There were generally higher concentrations of pollutants in mussels than in cod. Levels of radionuclides were higher in mussels than in cod. In summary, the blue mussel can be considered an appropriate matrix for monitoring biota in this supplementary study. In further operational monitoring, more analytical parameters will be included than in this supplementary survey, which in turn will affect the choice of indicator organisms. For example, M- 608 (2016) recommends monitoring of PFAS in fish. For a period, it may be an advantageous option to monitor both cod and blue mussel to consider the appropriateness of mussels versus cod as an indicator for PFAS-compounds.