Microplastics (MPs, <5 mm) are frequently detected in surface waters all over the world. Coastal waters, including urban fjords, are subjected to many potential sources of MP pollution. As such, the Limfjord in Northern Denmark is an interesting case study connecting two large marine water bodies, the North Sea, and the Kattegat. In this study, we took samples in eight areas of the Limfjord’s surface water deploying both a neuston net (300 µm mesh) and a pump-filtration device, UFOsystem (10 and 300 µm filters) to compare these approaches and identify potential correlations. MPs were extracted following a harmonized approach with a multi-step enzymatic-oxidative treatment, state-of-the-art µFTIR spectroscopy analysis, and systematic identification utilizing the software siMPle. We characterized MPs regarding their polymer type, size, shape, and for polyolefins weathering status. Additionally, we also investigated the potential of MPs smaller than the mesh size of the net (300 µm) to be incorporated in aggregates and compared the abundance and composition with the ones from the filtration device. Overall, preliminary results show that larger MPs (>300 µm) are by a factor of 1000 less abundant and less diverse in terms of their polymer composition than small MPs (10-300 µm). However, in both cases, the most dominant polymer types were polyester, polyethylene, and polypropylene. Thus, our findings contribute to the considerations of representative sampling and quantification of biologically relevant MPs (regarding size and polymer type) considering ecological risk assessment.

Primary Presenter: Claudia Lorenz, Aalborg University (clo@build.aau.dk)

Authors:

Claudia Lorenz, Aalborg University  (clo@build.aau.dk)

Fides Hensel, Aalborg University  (fides.hensel@gmail.com)

Alvise Vianello, Aalborg University  (avia@build.aau.dk)

Marziye Molazadeh, Aalborg University  (marziyem@build.aau.dk)

Laura Simon Sánchez, Aalborg University  (lasisa@build.aau.dk)

Jes Vollertsen, Aalborg University  (jesvollertsen@build.aau.dk)

Inga Kirstein, Alfred-Wegener-Institut (AWI)  (inga.kirstein@awi.de)