Evaluation of the time and spatial-dependent microplastic pollution in aksu river and its tributaries under the influence of anthropogenic pressures.

Microplastic pollution has emerged as a serious global problem due to its toxicological effects on aquatic ecosystems. It can accumulate in organisms in aquatic ecosystems via the food chain and lead to toxicological effects. The transfer of this pollution to water sources occurs through rivers from terrestrial environments. However, research on rivers in Turkey is limited. Therefore, this thesis aims to evaluate the time and location dependent microplastic pollution in the Aksu River and its tributaries in Antalya. Field samples were taken representing the pre- and post-rain season in September 2022 and April 2023. Twenty sampling stations were selected to represent the Aksu River and its tributaries, and a total of 2958 microplastic particles were identified. The examined microplastics were limited and six different types of microplastics were found after classification: dyes, fibers, films, fragments, foams and rubbers. The most common colors of these different types of microplastics were determined to be blue, black, transparent and red. The polymer structure of MPs were determined using FTIR (Fourier Transform Infrared Spectroscopy) analysis. Data on why plastic usage occurs in the basin was obtained by examining the polymer structure of MPs in the Aksu Lower Basin. CLC (Corine Land Cover) data were visualized in the QGIS program to reveal the relationship between MPs and terrestrial use. Considering the limited research on microplastic pollution in rivers in Turkey, this study aimed to assess the impact of HPP on reducing MP pollution on the Aksu River, determine all points where MP pollution can be caused by the breakdown of macro plastics accumulated in the riverbed and develop waste management for the basin. Management plans for activities that will create MP pollution in the aquatic environment, such as plastic waste generated after production in industry, collection areas for plastic agricultural waste before and after harvesting, and greenhouse materials used in agriculture, should be developed. This thesis not only contributes to the scientific literature in the country but also contributes to improving points that are sources of environmental pollution. Previous studies focused on the effects of phosphorus fertilizers, levels of polycyclic aromatic hydrocarbons, and soil and groundwater pollution due to fertilizer and pesticide use in the Aksu River and its tributaries. This research not only focuses on microplastic pollution but also systematically evaluates anthropogenic pressures and provides new findings. Keywords: Microplastic (MP) Pollution, Terrestrial Use, Water Pollution.