Microplastics pollution detected in pristine lakes in the Arctic region

, Vianello Alvise, Farstad Nashoug Benedikte, Lorenz Claudia, Pettersvik Arvnes Maria, Gomiero Alessio, Fabres Joan.

Microplastics (MP) have been detected worldwide, even in remote areas. Up to date, it is unclear whether there still exist pristine environments or MP pollution has become a ubiquitous global issue. To better understand the extent of this issue and to assess the baseline concentration of MP in pristine environments, we investigated three lakes in the arctic region (Lofoten Islands, Norway) with low levels of anthropogenic impact. Surface water samples were taken at two points at each of the lakes utilizing a custom-built and already well-established filtration device (UFO system), enabling sampling of MP in the range of 10–5000 µm. MP were extracted by using a multistep enzymatic and catalyzed oxidative treatment and were analyzed by µFTIR imaging followed by automatic identification, quantification and particle analysis pipeline (siMPle). Special care was taken to reduce contamination from atmospheric deposition by collecting air blanks at each location as well as performing a procedural lab blank, and finally subtracting the recorded contamination from the sample's results. Preliminary results revealed low MP concentration ranging from 0 to 45 MP/m3. The average concentration of 20 MP/m3 was comparable to the lower concentrations detected in marine water and drinking water studies. Most of the detected MP (59%) were in the size range of 11-75 µm, and only 10% was larger than 500 µm. Polypropylene (PP) and polyester (PEST) dominated the polymer composition with a lower contribution of polyamide (PA) and polyvinyl chloride (PVC). The polymer composition and overall small particle size are hinting towards atmospheric deposition as a major source of the MP accumulating in these lakes. These results show that MP pollution, in very low concentrations, has reached even pristine freshwater environments in the Arctic. Furthermore, the results highlight the importance of sample contamination prevention and assessment, especially when dealing with low-level MP concentrations.

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