Using a Citizen Science Approach to Assess Nanoplastics Pollution in Remote High-Altitude Glaciers

Microplastics have been found in almost every environment on Earth. As it is known that microplastics gradually degrade into smaller particles, eventually reaching the nanoscale, one naturally expects to find nanoplastics in all of the places where microplastics are found, but in even greater numbers. Such nanoplastics have been shown to adsorb organic pollutants and to cross cell membranes in vitro. While not fully understood, they may have an adverse effect on human health, and therefore warrant further investigation. However, analysing nanoplastics is challenging. Firstly, the more commonly used measurement techniques have limitations at this scale. Secondly, while micro- and nanoplastic research has predominantly concentrated on marine and fluvial environments, atmospheric transport is believed to be significant, particularly for nanoplastics, and it is difficult to sample the atmosphere systematically. In this study, we combine high-sensitivity trace science methods with sampling the surface snows from high-altitude glaciers as a proxy for airborne micro- and nanoplastics. This was facilitated by a citizen science sampling strategy involving mountaineers from the HLR 22 Expedition (www. high-level-route. com). This enabled us to obtain samples from otherwise inaccessible high-altitude glaciers in the Alps, thereby gaining a better insight into nanoplastics' presence and distribution in remote Alpine areas. We analysed particles in the < 1 m size fraction by thermal desorption-proton transfer reaction-mass spectrometry (TD-PTR-MS) using a method developed in previous studies. We fingerprinted the samples for common polymers (PE, PET, PP, PVC, PS and tire wear particles) and calculated a mass concentration for each polymer. Nanoplastics were detected at half of the sampled sites, with the majority by mass being PS and tire wear particles, showing just how pervasive nanoplastics are, even in places where humans rarely tread. Our results show the value of a citizen science approach to analysing nanoplastics in remote and pristine environments. Confounding factors in such a sampling strategy bring risks of lower reproducibility, human error and contamination. However, strategies can be implemented to reduce these risks, and the results obtained are a unique and valuable contribution to understanding nanoplastics pollution. We conclude that the trained citizen science sampling approach is feasible for expanding the analysis to remote regions worldwide. _PRESENT_PRESENT _PRESENT _PRESENT