The Arctic Deep Sea - A Sink for Microplastic ?

• Main Authors: Bergmann, Melanie, Wirzberger, Vanessa, Krumpen, Thomas, Lorenz, Claudia, Primpke, Sebastian, Tekman, Mine Banu, Gerdts, Gunnar
• Format: Conference Object
• Language: unknown
• Published: 2018
• Subjects: Arctic; Sea ice
• Online Access: https://epic.awi.de/id/eprint/46803/; https://hdl.handle.net/10013/epic.fc8a375e-30ab-4a03-9f59-9dec7ed5c914

Some 99 % of plastic debris projected to enter our oceans has not been captured by current global litter estimates based on empirical data. It has been speculated that a large fraction of plastic debris evades our detection through fragmentation into small particle sizes, uptake by biota and accumulation in remote environments such as the deep ocean floor, which covers 60 % of the Earth. Here, we analysed nine sediment samples taken at the HAUSGARTEN observatory in the Arctic at 2,340 – 5,570 m depths by Attenuated Total Reflection FTIR and µFTIR spectroscopy. Our results indicate the widespread occurrence of high numbers of microplastics (MP) in Arctic deep-sea sediments (44 – 3,463 MP L-1). The northernmost two stations harboured the highest MP quantities, indicating the importance of sea ice. A positive correlation between MP and chlorophyll a suggests vertical export via incorporation in sinking (ice-) algal aggregates. Overall, 18 different polymer types were detected dominated by chlorinated polyethylene (38 %), polyamide (22 %) and polypropylene (16 %). Almost 80 % of the MPs were ≤ 25µm. Many previous studies did not capture this size, which may partly explain why the MP concentrations are amongst the highest recorded from benthic sediments so far. MP quantities on the seafloor are 2 - 3 magnitudes higher than at the sea surface (Tekman et al.) indicating that the deep Arctic seafloor is a major sink for MP. This highlights the need to incorporate data from the deep sea into global litter estimates if we want to tackle the question ‘Where is all the plastic?’