Monitoring microplastics in a region with sensitive fish biodiversity: Tigris, Euphrates and Van Lake drainages in Irano-Anatolian hotspot

Microplastic (MP) pollution has emerged as a significant environmental threat, particularly in regions with sensitive biodiversity. The Irano-Anatolian Hotspot, home to diverse and endangered fish species, remains largely unexplored in terms of MP contamination. This study aims to assess MP pollution in the Tigris, Euphrates, and Lake Van drainages by investigating MP abundance, size distribution, polymer composition, and potential pollution sources. Surface water (SW) and sediment (SD) samples were collected from multiple stations, and MPs were identified using microscopic and spectroscopic analyses. MP abundance in SW ranged up to 545.4 MPs/m³, while SD samples exhibited values up to 33.2 MPs/kg. The results indicate that MP abundance is significantly higher near densely populated areas, suggesting a strong correlation with anthropogenic activities. The dominant MP types include fibers, fragments, and films, primarily composed of polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), pointing to sources, such as packaging materials, fishing gear, and laundry effluents. MP size distribution indicated that smaller particles (< 1 mm) accounted for 47.7% in SD, while larger MPs (> 1 mm) were more prevalent in SW (80.8%), highlighting the influence of hydrodynamic factors. These findings provide critical baseline data on MP pollution in the region while highlighting the urgent need for mitigation strategies. Taking into consideration, the potential bioavailability of MPs to aquatic organisms, future research should focus on seasonal variations and trophic transfer risks. Raising public awareness and implementing adaptive management strategies are essential for protecting the region’s aquatic and terrestrial biodiversity.