Abstract
The high concentrations of microplastics found in Arctic waters appear to contradict the region's pris-tine image and lack of nearby pollution sources. The numberofmeasurement serieson microplastics in the Arcticislimited. As part of the research project “Ecological tipping cascades in the Arctic seas,”microplastics in the fjords of Tunu (northeast Greenland) have now been surveyedfor the first time. At eight stations along the coast, 18 samples withthree to four fractions each were taken approximately sixmetersbelow the water surfaceusing the "Geesthacht Inert Microplastic Fractionator". The samples then underwenta two-step oxidative digestionand a density separation. Microplastic particles were identified and characterized regardingtheir number, polymer composition, and size distribution using automated quantum cascade laser-based infrared imaging.This method allows for the efficient analysis of large data sets with comparatively smallsubsampling errors. Out of the 641,512 particles analyzed, 100,881 were identified as microplastics. With 12±4L–1(1standard deviation(SD), n= 4, range 7.26–17.5L–1), the highest concentration of microplastics was found at the mouth of the Kangertittivaq. The concentrations in the other 14 samples ranged from 0.322–5.89L–1, without a clear spatial trend. The abundance of microplastic particles generally increasedexponentially with decreasing particle size. Among all 18 samples, polyethylene terephthalate (PET) is the most common polymer, accounting for an average of 96±3% (1SD, range 87.1–98.3%), followed by polylactic acid (PLA) with an average share of 1.6±0.5% (1SD, range 0.75–2.59%). Previous studies have found high proportions of polyesters in the open Arctic Ocean. Therefore, the consistently high concentrations of PET and PLA in the fjords of Tunu and the Denmark Strait suggest that microplastic inputs from glacial meltwaters play a minor role.However, it should be noted that tire abrasion and synthetic polyamides could not be investigated in this study.The high concentrations of PET in the Arctic are presumablycaused byriverineinputsofsynthetic fibers from laundry wastewater and the floating properties of PET bottles.
