# Pilot Study of Microplastics in Snow from the Zhetysu Region (Kazakhstan)
## 1 Introduction
In summary, polyethylene (PE), polyester (PES), and polypropylene (PP) are the most commonly found microplastics in snow cover due to their widespread use in plastic production. The analysis of microplastic forms shows a clear predominance of fibers, which are recorded in all studied regions. The sources of pollution are unevenly distributed. Both atmospheric transport and distribution by tourism are most frequent, which emphasis the need to develop international monitoring and control systems even for MPs pollution in sensitive natural areas. Therefore, microplastics deposited on a snowpack lower its albedo, leading to quicker absorption of solar energy and faster snowmelt. In the long term, this can affect the region's water resources by altering hydrological processes, and it poses a new threat to natural ecosystems, namely, soils [16; 17; 18]. Once in the soil, plastic persists for many years, undergoing mechanical and biological stress, ultraviolet radiation, and fluctuations in temperature and moisture. When microplastic concentrations are compared across environmental compartments, seasonal snow emerges as the most contaminated medium in terms of particle number density. Freshly fallen Alpine and Arctic snow can contain 190-154,000 particles m\({}^{-3}\)--several orders of magnitude higher than in any other natural matrix [19]. For comparison, atmospheric concentrations range from 0.01 particles m\({}^{-3}\) over the remote Pacific Ocean to 2502 particles m\({}^{-3}\) at roadside sites in London--three to five orders of magnitude lower than in fresh snow [20]. Surface ocean waters typically hold only 0.002-62.5 particles m\({}^{-3}\) (global mean \(\approx\) 2.76 particles m\({}^{-3}\)), two orders of magnitude below snowpack values [21]. In soils that have accumulated microplastics over decades, background levels seldom exceed 13,000 particles kg\({}^{-1}\); only the application of sewage sludge pushes concentrations above 71,000 particles kg\({}^{-1}\), approaching--but rarely surpassing--those of seasonal snow [22]. Thus, the seasonal snowpack functions as an extraordinarily efficient yet temporary atmospheric filter: when it melts, it releases a concentrated flux of microplastics into the soil, completing the transfer pathway \"air \(\rightarrow\) snow \(\rightarrow\) soil\", which remains obscured when each medium is examined in isolation. At present, there are no direct studies in the scientific literature devoted to the presence of microplastics in the snow cover of Central Asian countries. However, analysis of publications concerning microplastic contamination in other natural environments of these countries allows drawing certain conclusions about the potential contamination of snow cover as well. In Uzbekistan, in 2023, a study of surface water and bottom sediments of the Karadaya and Chirchik rivers, which are tributaries of the Syr-Darya, was conducted [23]. A significant content of microplastics was found in these rivers, where the dominant forms were microfibers (from 84 to 95%), and the main polymer was polyethylene terephthalate (PET). Sources of pollution were identified as wastewater discharges and ineffective waste management, particularly in the textile industry, indicating the widespread presence of microplastics in Uzbekistan's water systems and, by analogy, allowing for their presence in atmospheric deposition and snow cover. A wider regional review covering Central Asian countries, including Kazakhstan, Uzbekistan, Turkmenistan, Kyrgyzstan, and Tajikistan, highlights the very limited research on microplastics, which is due to both the inaccessibility of high mountainous areas and the lack of laboratory facilities for reliable analysis of microparticles. The authors of the review [24; 25; 26] pointed out the need to expand the monitoring of microplastic pollution, especially under conditions of a changing climate and increasing anthropogenic load.