Spatial and temporal distribution characteristics of microplastics in the lakeside zone of Jianhu, a plateau lake

Microplastics (MPs) pollution is a significant environmental concern. Plateau lakes have unique ecosystems, and their riparian zones play a crucial role in intercepting and filtering pollutants. This study, focusing on Jian Lake, examines different vegetation types in the riparian zone using density flotation to extract MPs from surface water and sediments. Results show that in surface sediments, the unvegetated riparian zone has the highest MPs abundance at 513 n/kg dw (dry weight), n represents the number of microplastic particles, significantly higher than vegetated zones. In surface water, the emergent plant zone has the highest MPs abundance at 49 n/m³, with smaller particle sizes. In contrast, the highest abundance in the littoral zone without emergent plants is found in the submerged plant zone, at 24 n/m³. In vegetated riparian zones, MPs abundance decreases from the shore towards the lake center, while in unvegetated zones, it increases. MPs in surface water and sediments are mainly small (0.2-0.5 mm), fibrous, and blue or brown, indicating stable anthropogenic sources. Surface water contains fewer MPs polymer types than sediments, with insignificant seasonal variation. This study is the first to reveal the differences in MPs retention and filtration functions of different vegetation types in Jian Lake's riparian zone. Vegetated zones, especially those with emergent plants, are significantly better at retaining MPs than unvegetated zones. These findings highlight the importance of protecting and restoring vegetation to enhance riparian functions, reduce MPs impacts on ecosystems, and promote the sustainable development of plateau lake ecosystems.