Environmental assessment of Grandefjæra near Ørland air base

Summary

Ørland military air base is located close to the coast in the municipality of Ørland in Trøndelag. Grandefjæra nature reserve, an international important wetland area, is located just west of the air base. During several years, there has been run-off of chemicals used for de-icing and chemicals from fire drill sites to Grandefjæra nature reserve. Due to expansion of the air base and increase of the air traffic, the Norwegian Defence Estates Agency (NDEA) wants to revise the discharge permit for Ørland air base. NDEA has been asked to provide information about how run-off from the air base might affect the biodiversity and water quality of Grandefjæra. The goal of this survey has been to provide new knowledge about the ecological status of Grandefjæra, and to describe possible environmental effects of the run-off. An investigation of the soft bottom fauna in the deep area of Grandefjæra was done to determine ecological status. The biodiversity of Grandefjæra does not seem to be affected by the run-off from the air base. The stations examined had “good ecological status”. The biodiversity in the shallow part of Grandefjæra was also examined. There were more organisms and larger biomass in Grandefjæra compared to the reference area, Innstrandfjæra, but no evidence of organic enrichment. There were normal levels of TOC (total organic carbon), low concentration of total nitrogen, there were no green algae, and no smell of hydrogen sulfide from the sediment. The biodiversity of the hard bottom area was also examined, and based on the macro algae vegetation of the inter-tidal area, the stations were classified to “good” and “moderate” condition. Observations done with drop camera revealed that the deeper part of the shore was affected by grazing of sea urchins. Perfluorinated alkylated substances were detected in samples of sediment from the deep part of Grandefjæra, and from the deep part of Innstrandfjæra. Several perfluorinated alkylated substances were detected in periwinkle sampled from Grandefjæra and Innstrandfjæra. The highest concentrations were found in periwinkle from the outlet of creek Leirbekken. The concentration of PFOS in periwinkle from Leirbekken exceeded the environmental quality standard (EQS).