Significant regional disparities in riverine microplastics

Research on riverine microplastics has gradually increased, highlighting an area for further exploration: the lack of extensive, large-scale regional variations analysis due to methodological and spatiotemporal limitations. Herein, we constructed and applied a comprehensive framework for synthesizing and analyzing literature data on riverine microplastics to enable comparative research on the regional variations on a large scale. Research results showed that in 76 rivers primarily located in Asia, Europe, and North America, the microplastics abundance of surface water in Asian rivers was three times that of Euro-America, while the sediment in Euro-American was five times that of Asia, indicating significant regional variations (p<0.001). Additionally, based on the income levels of countries, rivers in lower-middle and upper-middle income countries had significantly (p<0.001) higher abundance of microplastics in surface water compared to high-income countries, while the opposite was true for sediment. This phenomenon is preliminarily attributed to varying levels of urbanization across countries. Our proposed framework for synthesizing and analyzing microplastics literature data provides a holistic understanding of microplastics disparities in the environment, and can facilitate broader discussions on management and mitigation strategies. Through literature synthesis, we gathered data on microplastics from 76 rivers, mainly distributed in Asia and the Euro-American regions. Our extensive regional analysis showed notable variations in the presence of microplastics within surface water and sediment across these regions, underlining crucial aspects of managing riverine microplastic pollution. It suggests that developed countries need to concentrate on sediment-based microplastics, whereas developing countries should give precedence to microplastics found in water samples.