Identifying microplastics in North Sea waters - A matter of extraction and detection

In times of a rising plastic production the occurrence of microplastics (< 5 mm in size) in the marine environment has been identified as an emerging topic of global concern. Microplastics are omnipresent in our environment, hardly degradable and are easily ingested by a wide range of organisms throughout all trophic levels. However, the extent of this microplastic pollution as well as the resulting impacts on the marine environment remains largely unknown. Therefore, standardized and reliable methods to securely detect microplastics are urgently needed. The conclusive identification requires a successful extraction from different, complex environmental matrices. Thus we developed a highly promising procedure to successfully analyze also small microplastics (11-500 µm) isolated from surface water samples. This procedure includes the usage of an enzymatic-oxidative purification in newly developed semi-enclosed filtration units (microplastic reactors). This is followed by a state-of-the-art analysis via micro Fourier transform infrared (µFTIR) spectroscopy. The aim of this work is to contribute to the field of microplastic research by applying innovative analysis techniques as well as generating solid and comparable data. These provide information on quantities, polymer and size composition as well as spatial distribution of microplastics in North Sea surface waters. First results show that microplastics are present in the North Sea exhibiting a variety of polymer types, dominated by rubbers and polyethylene. Concerning the size, the vast majority of the detected microplastic particles is less than 75 µm in length.