Assessing microplastic pollution in a river basin: A multidisciplinary study on circularity, sustainability, and socio-economic impacts.

Plastic pollution has emerged as a significant environmental challenge worldwide, posing serious threats to ecosystems and human health. This study seeks to explore the interplay among circularity, sustainability, and the release of microplastics within the freshwater ecosystems situated along the western Black Sea coast- Düzce, Türkiye. Employing a multidisciplinary approach that integrates environmental science, economics, and policy analysis, the research examines the current state of plastic pollution in the region, considering diverse land uses and socio-economic lifestyles. Conducted over four different seasons, the current study identifies the prevailing types of microplastics in the region. Fibers dominate, comprising 86.7% in each season, followed by film and fragments at 7.7% and 7.0%, respectively. Notably, polyethylene (PE) and polypropylene (PP) emerges as the primary polymer types. The distribution of polymer types varies across different land uses within the region, emphasizing the influential role of land use in shaping the abundance polymer composition. The comprehensive assessment of pollution, as reflected in the overall pollution load index (PLI) of the Melen River indicating a concerning level of pollution (PLI>1). Finally, the study unveiled the relationship between socio-economic activities as well as the seasonal precipitation patterns, and microplastic contamination in the region. This underscored the importance of site-specific mitigation measures on reducing the amount of microplastics. Lastly, incorporating sustainable practices within the circular economy framework fosters a harmonious balance between economic development and environmental protection in Türkiye.