## 5 Conclusions  
This study was the first assessment of micro- and macrolastic pollution in the water area of Lake Markakol and its main tributaries in northeastern Kazakhstan. Lake Markakol is located within the Markakol Reserve, which is included in the UNESCO World Network of Biosphere Reserves, and it was previously considered to be unaffected by anthropogenic impacts. However, this study showed that Lake Markakol has also been affected by plastic pollution. The main sources of pollution here were recreational and poaching fishing, a lack of organized collection of solid waste as well as a low level of environmental awareness for both tourists and the local population. We identified the main inflowing rivers as sources of plastic and MP inputs into the lake, but non-point plastic and MP inputs were also proven. The comparison of the MP concentrations in the tributary rivers, in just the effluent river and within the lake shows clearly that Lake Markakol is functioning as a MP sink. MP measurements in different zones of the lake showed higher MP concentrations under the influence of the northern lake coast and the Topolevka, Tikhushka, Zhirelka and Yelovka tributary rivers. The corresponding MP concentrations along the south coast of the lake under the influence of the Matabai River tributary and the out-flowing KazhyrRiver were quite lower. This MP content pattern was probably caused by both local inefficient waste management of the rural villages and the increasing number of tourists. Although the total number of plastic-wasting tourists was low in the Lake Markakol study area in comparison with other mountain lakes, despite the remoteness, inaccessibility, low population and harsh natural and climatic conditions, the number of tourists has increased. According to the reference data of the \"Markakol State Nature Reserve\" RSE, the growth of tourists at Markakol Lake for the last 5 years has increased from 661 to 892 people per season. Therefore, continued monitoring of plastics in aquatic ecosystems is an important step in understanding the extent of the problems and developing effective pollution management strategies. For analyzing of the MP status of Lake Markakol the first time, the investigation approach, analyzing the MP pollution in both the inflowing rivers and in different lake zones, was suitable. However, to extend the knowledge about the input, storage, including transformation and output situation of MPs, repeated inspections are necessary, both during the same season and during other seasons. Determining the exact sources of origin of plastics will be the subject of future research, including use of the FTIR and Raman spectroscopy methods, which will allow us to more accurately determine the origins of new pollutants. These observations emphasize the importance of the interaction of the geographical, hydrological and climatic features of a study area for MP analyses in aquatic systems. Additional research may help to understand the processes occurring in Lake Markakol and its catchment area better as well as provide recommendations for managing and reducing plastic pollution in the area. The results of this study can be used for the development of more large-scale projects on MP problems in lakes. The knowledge about the presence of MPs in water bodies in the Republic of Kazakhstan will improve the understanding of the dimension of MP pollution problems and their impact on the aquatic environment. The study area of Lake Markakol and its tributaries seems to be especially suitable because of their insularity and the closed catchment situation with only one outflow. Addressing this problem requires comprehensive measures such as raising awareness of waste management, improving waste management, encouraging a shift to alternative materials and actively implementing measures to clean up and restore polluted aquatic ecosystems. The final results emphasize the need to take measures to prevent pollution of water systems and develop strategies to reduce the use of plastic materials in the region.