Microplastics in the upper tidal Elbe - A comparison between sediments from the Hamburg port area and an adjacent nature reserve

, Motyl Larissa, Ruff Ines, Fischer Elke.

In cooperation with the Hamburg Port Authority (HPA) and as part of the S̈ullied Sedimentsp̈roject funded by the European Union, sediment samples within the Hamburg port area were taken at three sites of different location within the harbor. The sites S̈tover Strandänd Ẅedeläre located upstream and downstream of the port of Hamburg, while K̈öhlbrandïs located in the centre area of the port. Additionally, another sediment sample was taken in the adjacent Hamburg nature reserve Ḧeuckenlock̈. For the analysis of microplastic concentrations in the samples, the biogenic organic matter was removed by digestion (H2O2 30%, HCl 10% and NaClO 6-14%) followed by wet sieving and a density separation with NaI (density: 1.5 g/cm3). For identification the Nile red staining method in combination with fluorescence microscopy (Axioscope 5/7 KMAT, Zeiss) was applied. A subset of identified synthetic polymers was investigated for polymer composition via µRaman spectroscopy (DXR2xi Raman Imaging Microscope, Thermo Fisher Scientific) and additional FTIR analyses. A total number of 18 sediment samples from different depths below riverbed level were examined. Overall, 2,756 microplastic particles could be recorded. Highest numbers were found in the sample at 0-2 cm depth below riverbed level in the sediment of Stover Beach (32,356 particles per kg dry sediment). In the sediment of the nature reserve Heuckenlock the highest concentration was found at a depth of 10 cm below riverbed level (3,835 particles per kg dry sediment). The lowest microplastic concentrations were found at the Köhlbrand site (minimum 1,114- maximum 2,776 per kg dry sediment) and in Wedel (minimum 743- maximum 3,133 per kg dry sediment). At the locations Heuckenlock, Köhlbrand and Wedel fragment dominate, while at Stover Strand fibers are the most common shape. Furthermore, a significant correlation between the biogenic organic matter content and the microplastic concentration could be detected.

View online