Distribution Characteristics of Microplastics in Domestic Sewage Waters: A Case Study in Guilin City, China

Abstract Microplastics (MPs) resulting from plastic fragmentation with a size less than 5 mm have become one of the main pollutants endangering the water environment. Therefore, it is necessary to know about the abundance and size distribution in sewage waters as well as the influences of water quality on MPs. In this study, water samples are collected from 20 sewage outlets in Guilin, China, to analyze the abundance and morphology of the MPs and their hydrochemical characteristics. Multivariate statistical analyses are conducted to identify the major factors related to the MPs’ distribution in sewage waters. Results show that MPs in sewage water are mainly composed of fiber and film, and about 67.8% is in the size of <0.3 mm. The abundance is in the range of 6 (±1)–47 (±3) items/L. The correlation analysis presents that the abundance of MPs is weakly correlated with hydrochemical parameters and metal ions due to the complexity of the abundance data. The redundancy analysis indicates that the MPs’ morphology distribution is significantly affected by NO3-N, Zn, Ca, and Cu contents, and the MPs’ size distribution is mainly related to Zn, Ca, and Cu contents. The study highlights the occurrence characteristics and environmental influencing factors of the MPs in sewage water, which may be significant for future studies on the pollution control of MPs.