Characteristics of microplastic pollution in sediments and error analysis of ecological risk assessment in Qin River, China

Accurately assessing the ecological risks of microplastics is crucial for a comprehensive understanding of their potential environmental hazards. This study focuses on the Qin River in Jincheng City, China, as the research area. By collecting river sediment samples, the occurrence characteristics of microplastics in the samples were qualitatively and quantitatively analyzed using stereomicroscopes and Fourier transform infrared spectroscopy, and the primary sources of pollution were evaluated. The results showed that the abundance of microplastics in the sediment was 80-1360 items/kg; secondary microplastics with fragments, fibrous, and white appearances dominated. Polyvinyl chloride (86.5 %) is the main contributing polymer to the ecological risk of microplastics in the area. However, during the ecological risk assessment, it was found that some types of microplastics were not included in the statistics due to the lack of hazard score data, with ethylene-propylene copolymer (PE-PP), which accounted for 8.2 % of the detected amount, being particularly prominent. Consequently, this study has preliminarily estimated and analyzed the ecological risk it causes. The findings elucidate the inherent uncertainties associated with the ecological risk assessment of PE-PP and furnish seminal insights and methodological considerations for the precise evaluation of microplastic ecological risks in forthcoming research endeavours.