Review of microplastics in lakes: sources, distribution characteristics, and environmental effects

Microplastics (MPs) are contaminants that damage lake ecosystems by enriching pollutants. This study investigated the current state of MPs in lakes using the bibliometric method and correlation analysis. The results show that the abundance of MPs in lakes is negatively correlated with the depth and area of lakes and distance to populated areas, and positively correlated with the surrounding population density. The main factors influencing MP abundance were human activities, including pollution diffusion and waste generation from agricultural, industrial, and domestic activities. MPs are prevalent in water systems and vary by type and shape. Moreover, MPs are vertically distributed in lakes, resulting in high concentrations in sediments. Lake ice caps adsorb MPs from water and air during freezing, leading to higher concentrations of MPs on the surface and lower layers of ice caps (10–100 times higher than in water). Moreover, mechanisms underlying the toxic effects of MPs on organisms in aquatic ecosystems are identified in the study. MPs can inhibit the growth of aquatic plants by suppressing photosynthesis. When combined with other pollutants, MPs disrupt energy metabolism, cause physiological changes in the liver, and even lead to the death of aquatic organisms. We established that the evidence regarding the migration regulation of MPs in ice, water, sediment, and other multi-media is currently insufficient and requires further exploration. This study aims to identify sources, pathways, regulations, and effects of MPs in lakes to support future research and solutions. Graphical Abstract