Microplastic pollution and characteristics in the surface waters of the middle and lower reaches of the Han River along Hubei Province, China

Microplastic pollution in freshwaters has received attention globally. The Han River is the largest tributary of the Yangtze River, and limited information is available on microplastic pollution in this river. The occurrence and characteristics of microplastics in the surface waters of the middle and lower reaches of the Han River along Hubei Province were investigated in this study. Microplastic abundance ranged from 2315 +/- 603 to 8406 +/- 2055 n/m(3) and generally showed an increasing trend along the flow direction. Small-sized (< 500 mu m) fibers were the most dominant microplastics. Polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE) and polyamide (PA) were the main polymer microplastic types detected via Raman and FTIR spectroscopic identification. SEM analysis revealed degradation textures on some microplastics, which illustrated that they had experienced various levels of mechanical erosion and chemical weathering, but some fibers consisted of primary microplastics. EDS analysis revealed that the heavy metals Zn, Ni, and Cu were absorbed on the microplastics. According to analyses of microplastic morphological and microscopic characteristics, clothes laundering, plastic wastes from human activities, and agricultural production may be the microplastic sources in the Han River water. We suggest treating microplastics from domestic sewage and managing plastic wastes around the Han River basin to reduce microplastic pollution from these sources.