Distribution Characteristics and Sources of Microplastics in Inland Wetland Ecosystem Soils

Microplastic (MP) pollution, an emerging global change factor, disturbs the ecosystem functioning. Inland wetlands, providing important ecosystem services, might be an important sink for MPs. Understanding the distribution, source, and fate of MPs in inland wetland ecosystems is a prerequisite for developing an effective management strategy. Here, different types of inland wetlands, including the river wetland, constructed wetland, and lake wetland, were selected to explore the pollution patterns of MPs therein. Results showed that the abundance of MPs in wetland soil ranges from 532 to 4309 items/kg. Transparent, fibers, and polyethylene terephthalate were the most common color, shape, and polymer type of MPs, respectively. The constructed wetland in this study did not significantly remove MPs. The lake wetland was one of the main sinks for MPs in the inland wetland ecosystem and had accumulated large amounts of MPs. In addition, MP characteristics and cluster analyses showed that aquaculture, agricultural cultivation, and domestic waste were the most important sources of MPs in the study area. The occluded particulate organic carbon content in this study was related to MP abundance. In conclusion, this study reveals the pollution characteristics of MPs in the special inland wetland ecosystem of river-constructed-lake wetlands, which would help to better understand the distribution and source of MPs in inland wetlands and have implications for the subsequent pollution control and ecological restoration of inland wetlands.