Quantification and distribution of microplastics in the sediments of the Yellow River (China)

Microplastics are increasingly recognized as a widespread pollutant in freshwater environments, with river systems playing a key role in their transport and accumulation. The present study focuses on the quantification and spatial distribution of microplastics in the sediments of the Yellow River, China, one of the world’s most dynamic and heavily used rivers. Across 20 sediment samples, a total of 665 microplastic particles were identified, with concentrations ranging from 1400 to 5600 items/kg (average: 3325 items/kg), indicating widespread but spatially uneven contamination. The results show that microplastic distribution along the Yellow River cannot be described solely by a simple upstream-downstream trend, but also through the combined influence of sedimentological conditions, hydrological dynamics, and human activities. Overall, the Yellow River proves to be a complex system in which microplastics are repeatedly stored, mobilized, diluted, and redeposited over short distances. By providing an integrated assessment of microplastic abundance and distribution across the river corridor, this thesis highlights the importance of more frequent and spatially comprehensive monitoring in large rivers, as a clearer understanding of how microplastics behave within such dynamic and human-influenced systems is vital for improving pollution mitigation strategies, protecting aquatic environments, and sustaining the Yellow River’s essential functions in agriculture, water supply, and regional ecology. Ultimately, strengthening this knowledge base is essential for creating effective management strategies and securing the long-term resilience of one of Asia’s most vital river systems.