The occurrence characteristics and ecological risk level of microplastics in the water and sediments of the Anhui section of Huaihe River Basin were analyzed via field sampling, stereomicroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), risk index (H), and pollution load index (PLI) model. The current situation of microplastics in the water and sediments of the basin was analyzed, and the ecological risk assessment of microplastics was conducted. The results showed that the detection rate of microplastics at each site in the basin was 100%. The average abundance of microplastics in surface water and sediments was (39800±3367) n·m-3 and (5078±447) n·kg-1, respectively. The average abundance of microplastics in the downstream was higher than that in the upstream and midstream. The particle size of microplastics in water and sediments was primarily 20-150 μm, accounting for 82.96% and 80.77%, respectively. The microplastics were primarily fiber (water 76.05%, sediment 84.53%), film (water 21.83%, sediment 15.43%), and debris (water 2.12%, sediment 0.04%). The microplastics in water and sediments were primarily transparent, accounting for 63.31% and 83.69%, respectively. Polyethylene (65.74% in water and 80.62% in sediment) and polypropylene (18.43% in water and 9.71% in sediment) were the major components of water and sediments. Microplastics were primarily derived from agricultural films, abandoned fishing gear and nets, and artificially abandoned plastic bags in ports. The microplastic risk index (H) model assessment revealed that the risk index of some sites was high, and the risk level of microplastics in the Anhui section of Huaihe River Basin was grade II. The pollution load index (PLI) model assessment revealed that the ecological risk of surface water and sediments in the basin was generally low.
Keywords: Huaihe River Basin; microplastics; occurrence characteristics; risk assessment; sediment; surface water.