Sammendrag
The global concern about microplastics (MP) has grown considerably since their first detection in the marine environment and wildlife. Ocean sediments may constitute the ultimate sink for MPs, both for denser plastics such at nylon, polyethylene terephthalate (PET) and polyvinylchloride (PVC) and for low-density polyolefins (e.g. PE and PP) which may aggregate and increase density over time due to biofouling. Still, little is known about the concentrations and impacts of MPs in benthic ecosystems. A previous study has seen potential bioaccumulation of microplastics in tube-dwelling polychaeta when compared to MP concentrations in their surrounding sediments. These polychaetes burrow in sediments and embed their tubes with particles from their surroundings, thus potentially also MPs. These results indicated that the feeding behaviour and life cycle of polychaetes could have an important influence on the transport, distribution and food-chain dynamics of microplastics in sediments. The present study aims to investigate potential differences in MP levels and quantify MP in sediments and polychaeta from offshore and coastal areas in Norway. The study also aims to investigate potential differences in MP levels in tube-dwelling and deposit feeding polychaeta without tubes. A total of 9 sediments samples (0-1 cm) and 24 polychaeta samples, both tube-dwelling and deposit feeding, were collected from offshore and coastal areas in Norway between 2017 and 2020. The offshore samples were collected on the Norwegian Continental Shelf and in the Barents Sea, while inshore samples were collected at Ålfjord, Lindesnes, Nordgulfjord and Oslofjord. Offshore sediments were sampled at remote locations or adjacent to oil platforms, which constitutes a probable local source of microplastics other than aquaculture and shipping in these areas. The inshore sediments are most likely more affected by anthropogenic sources of microplastics such as emissions from waste-water, various industry, aquaculture and boat traffic. Analyses of MPs > 45µm in sediments and polychaeta were performed using density separation with ZnCl2:CaCl2 solution (ρ ≥ 1.52 g/cm3), and chemical digestion using a twostep procedure with NaOH:thiourea:urea to dissolve cellulosic material and further chemical oxidation with NaOH and H2O2. Finally, the samples are analysed using µFT-IR which will be performed during December 2021. Funding was provided by the Norwegian Retailers' Environment Fund and NGI.
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