Microplastics in fishes and their living environments surrounding a plastic production area

Microplastic-associated risks in freshwater ecosystems have triggered significant concerns in recent years. However, the contribution of plastic production processing to microplastic pollution is largely unknown. The present study investigated microplastic pollution in biotic and abiotic compartments in three sites which are in surrounding area of a plastic industrial colony and a site from a reservoir for drinking water as reference. The abundances of microplastics were 0.4-20.5 items/L in surface water, 44.4-124.7 items/kg (ww) in sediment and 1.9-6.1 items/individual in guts of Hemiculter leucisculus from the industrial area. In contrast, the abundances were much lower levels of 0.1 ± 0.1 items/L in surface water, 0.5 ± 0.2 items/kg (ww) in sediment and 0.2 ± 0.01 items/individual in H. leucisculus in the reference site, respectively. A large quantity of raw pellets were found on the grounds surrounding the plastic factories. The dominant shapes of microplastics found in sediment were fragments (67%), followed by pellets (18%). Unexpectedly, neither fragments nor pellets (> 1 mm) were found in any fish. The organ index of liver in Hemiculter leucisculus, including four types of histopathological changes, was up to 5.5-9.9 in the plastic production area and only 1.6 in the reference site. Our results strongly suggest that microplastic pollution was in high level, and the histopathological damage in fish tissues strongly confirmed the microplastic pollution and ecological response of the plastic production area. Our results also indicate that the feeding types of local fish species might be the reasons leading to the absence of raw pellets or fragments in fish, despite high abundances of microplastics existed in their living environments. CAPSULE ABSTRACT: The plastic production area is a special point source of microplastic in the environments.