[Microplastic Pollution Status and Ecological Risk Evaluation in Weihe River]

This study aimed to explore the occurrence state, morphological characteristics, polymer types, as well as potential ecology of microplastics in the Weihe River in Northwest China. Thus, we identified the abundance distribution, shape, particle size, color, and polymer type of microplastics in the surface water of the Weihe River by conducting field sampling, microscope observation, Fourier infrared spectroscopy, Micro-Raman spectroscopy, etc., during the normal water period (May) of 2021. Subsequently, we analyzed the potential ecological and environmental risks of microplastics using the pollution load index method and species sensitivity distribution method. The results showed that microplastics were detected to exist in all sampling points and the abundance ranged from (2.9±0.8) to (10.3±2.8) n·L^-1. The concentration of microplastics in the main stream of the Weihe River was higher than that in the tributaries. Fiber (15.04%-77.03%), small size (<0.5 mm) (27.27%-89.38%), and colored (15.85%-49.53%) were the predominant microplastic types. Polyethylene (32.98%), polypropylene (29.79%), polystyrene (21.21%), and polyethylene (10.61%) terephthalate were the main types of polymers detected. In general, the microplastic pollution in Weihe River was at a medium level and had not affected aquatic organisms, but its high concentration and the characteristic of the plastics to adsorb other pollutants are still of concern.