Abstract
Deposition of mine tailings in fjords along the Norwegian coast is known to have ecological implications for benthic fauna, but little information is available on the potential impacts on pelagic organisms. Depending on local hydrology, deposition of tailings can result in plumes where the particle size distribution may be in the sub-micron range. Whilst the bulk of the of the tailings will settle onto the sea floor close to the release point, the sub-micron fraction is likely to remain suspended for longer time periods and for transport be more extensive. Calanoid copepods, such as Calanus finmarchicus, are important pelagic species serving a crucial link in the food chain between primary producers and fish. Their impressive capacity for filtering sub-micron particles for food suggests that they will readily ingest mine tailing particulates, with subsequent exposure to metal ions dissolving from the tailings. We report experimental data for the purpose of environmental risk assessment of mine tailing deposits in Norwegian fiords, where the acquired data will be used to inform risk models. The physicochemical properties of the mine tailing fraction remaining suspended in seawater for an extended period (e.g. 10 d) is comprehensively characterised (composition and particle size distribution). Copepod filtration rates will be determined for different size fractions of the mine tailings, copepod sensitivity determined for different elements (relevant to mine tailings) in the dissolved phase, and uptake and depuration rates of different elements. Finally, we will determine potential implications of environmentally realistic exposures (particle size distributions and concentrations) to mine tailings on copepod survival, growth and reproduction. Environmentally realistic exposure experiments will be designed based on data from field surveys in fjords during deposition of mine tailings using the LISST-100, LISST-HOLO and in-situ particle imaging systems.
