Microplastics are novel pollutants in the environment, and with the awareness of microplastic pollution, the migration of microplastics in freshwater wetland environments such as rivers and lakes has received widespread attention. The wetland of Poyang Lake, the largest inland freshwater lake in China, is influenced by the five river basins and their surface runoff, and the microplastic pollution in the wetland water environment cannot be ignored. In order to understand the occurrence of microplastics in the water bodies of Poyang Lake and the adsorption and interception effects of aquatic plants on microplastics, five river basins of Poyang Lake, including the Ganjiang River, Xinjiang River, Fuhe River, Xiushui River, and Raohe River, were selected as the study area, and the water samples of each basin and the prevalent floating plant Eichhornia crassipes were used as the research objects to study the adsorption and interception characteristics of microplastics in the water of the Poyang Lake basin. The study investigated the adsorption and interception characteristics of E. crassipes on microplastics in water bodies, explored whether the aquatic plants had adsorption or interception effects on microplastics in the water bodies, clarified the correlation between the adsorption of microplastics by E. crassipes and microplastics in the water bodies, analyzed the migration characteristics of microplastics in the wetland environment, and provided a theoretical basis for the control and pollution management of microplastics in the wetland environment of the Poyang Lake basin. A total of 18 sampling points were set up in the main entry areas of the Ganjiang River, Fuhe River, Xinjiang River, Raohe River, and Xiushui River, and the exit of the lake into the Yangtze River confluence area in the Poyang Lake basin, and water samples were collected from the all the E. crassipes floating on the water surface and water at a depth of approximately 1 m. Microplastics were separated from water samples and the plant surface at the root zone of E. crassipes by filtration; after the water samples were disintegrated with an HNO3 (65%)-H2O2 (30%) reagent mixture, the microscopic identification method was used. The microplastics were characterized by color, particle size, and morphology, and the abundance of microplastics in the water and E. crassipes root zone was calculated using Nano Measurer 1.2 software, and the polymer composition of different forms of microplastics was identified via Fourier transform infrared (FTIR) spectroscopy. The abundance of microplastics in the water samples of the Poyang Lake basin was moderately high, ranging from 65.5 to 353 n•L-1, and the small-sized microplastics in the range of 0-0.5 mm mainly accounted for more than 80% of the microplastics in the water samples of the basin. The abundance of microplastics retained or adsorbed by E. crassipes in the basin ranged from 36 to 204 n•kg-1, and the small-sized microplastics in the range of 0-1.5 mm mainly accounted for more than 80% of the microplastics in the water bodies of the basin. The abundance of microplastics retained or adsorbed by E. crassipes in different watersheds ranged from 36 to 204 n•kg-1, and the proportion of small-sized microplastics in the range of 0-1.5 mm was more than 80%. The abundance of microplastics in the particle size range of 0-0.5 mm adsorbed by E. crassipes was significantly correlated with the abundance of microplastics in the particle size range of 0-0.5 mm in the water bodies. The effect of E. crassipes on microplastics in the water column was significant. The polymer composition of microplastics in the water samples of the five river basins of Poyang Lake included mainly polyethylene and polystyrene, the abundance of microplastics in the water samples of the Poyang Lake basin was at a high level, and the main microplastics were of small particle size in the range of 0-1.5 mm, which easily pose ecological risks to the water body organisms and water environment. The abundance of microplastics in the range of 0-0.5 mm particle size was significantly correlated with the abundance of microplastics in the range of 0-0.5 mm particle size in the water body. Eichhornia crassipes also had a strong adsorption effect on microplastics in the water body, which can be used by aquatic plants to adsorb or retain microplastics in the water body. The strong adsorption effect of E. crassipes on microplastics in the water column can provide a reference for the adsorption or retention of microplastics in the water column. © 2022, Science Press. All right reserved.
