First insights into plastic and microplastic occurrence in biotic andabiotic compartments, and snow from a high-mountain lake (CarnicAlps)

Plastic pollution has become a pervasive environmental problem on a global scale, from the ocean depthsto the aquatic ecosystems of the Tibetan Plateau. To date, data on plastic and microplastic occurrence inpristine ecosystems like high-mountain lakes are lacking. In this study, plastic (>5000mm) and micro-plastic (10e5000mm) levels were measured in snow at the end of the winter season (April 2020), and inwater, sediment, and biological samples collected monthly (JuneeOctober 2019) during the ice-freeseason from the Dimon Lake, a high-mountain lake in the Carnic Alps, northeast Italy. Biological sam-ples consisted of chironomids (Diptera, Chironomidae; n¼150) and stomach contents ofCottus gobio(n¼40). Analysis of the water, sediment, and biological samples revealed the absence of plastic andmicroplastics larger than 10mm, whereas the snow samples contained microplastics ofpolyethyleneterephthalate (PET) albeitat very low levels (0.11±0.19 L-1). These results show that while the lakeecosystem could be considered unpolluted by microplastics, abundant snow precipitation in winter cantrap microplastic particles that deposit on the ground. The very low levels of PET microparticles recordedin the snow samples suggest the need for further research to better understand the source of micro-plastic pollution in this environmental matrix.