Sampling micro- and nanoplastics at Boknis Eck station (Eckernförde Bay)

The sediment trap onboard of the RV Alkor.

In the morning hours of January 18, the RV Alkor, the main research vessel of GEOMAR, is leaving its home port, Kiel and is heading to the station Boknis Eck in Eckernförde Bay – an area that has been continuously monitored by GEOMAR scientists and their predecessors since 1957. Native waters, so to speak.

On board this time: Scientific divers from Kiel University and a small team of researchers – among them Sandra and Stefan, who are supervised by Prof. Anja Engel and work at GEOMAR within the PlastTrack project. The German-Danish Interreg project is exploring plastic contamination along the Western Baltic coastline. It aims at shifting the focus to the very small plastic particles that might be present in the environment. At sizes down to a few hundred of the diameter of a human hair, these small micro- and nanoplastics are not only invisible to the human eye but still fly under the radar of most current methods for sampling and analyzing plastics.

Sandra and Stefan spent the past days testing and preparing what stands on deck now, lit by the first rays of the sun: A sediment trap constructed in Silkeborg by KC Denmark and modified at GEOMAR to be moored in the Baltic Sea today. Will everything go well? The tension rises slightly among all participants while the last preparations and checks are conducted. Luckily, it will be relieved before noon, when the divers confirm the successful deployment, and everyone gathers to watch the underwater video footage they just recorded. It shows the sediment trap hovering at a depth of 9 m. The trap’s cone is designed to capture any solids on their way to the seafloor – among them plastic particles, some of which might be enclosed in remnants of algae and other biomass sinking down from the upper water layers.


On their way home, Sandra and Stefan have already considered their return: In June, they plan to recover the 20 samples, which the sediment trap will collect automatically throughout the following five months. Moreover, they want to test further sampling methods.

 Read this article in Danish or German.

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