The increasing microplastics (MPs) pollution in freshwater wetlands has received global concerns. To investigate the spatiotemporal dynamics of MPs in the wetlands of Poyang Lake, surface water and sediment samples were collected from five rivers entering the lake as well as the confluence of Poyang Lake into the Yangtze River, in both dry and wet seasons. The MPs in water and sediment were extracted by the digestion-filtration method and flotation-separation-digestion-filtration method, respectively. Light microscope, Fourier transform infrared spectroscopy, and scanning electron microscope were used for microplastic characterization. The results showed that the abundance of MPs ranged from 32.1 to 127.3 n·L-1 in water samples, and from 533.3 to 1286.6 n·kg-1 in sediment samples during the wet season. In the dry season, the abundance of MPs ranged from 87.1 to 295.5 n·L-1 in water and from 460.0 to 1368.0 n·kg-1 in sediment. Compared with other freshwater wetlands, Poyang Lake had higher abundance of MPs. There were temporal and spatial differences among regions. The main forms of MPs included beads, fragment, film and fiber, and the corresponding polymer components were mainly polystyrene, polypropy-lene and polyethylene. Beads (35.7% in wet season and 52.0% in dry season) were the main form of MPs in water, while fragment (45.8% in wet season and 69.7% in dry season) was the main form of MPs in sediment. Small size (<0.1 mm) MPs were dominant (>50%) in water and sediment in both seasons. The abundance of MPs with different sizes decreased with the increases of size. The potential main sources of MPs in the wetlands of Poyang Lake included the discharge of industrial wastewater, discharge from urban and rural domestic sewage treatment plants, agricultural and fishing activities, and improper disposal of domestic wastes.
淡水湿地中日益严重的微塑料(MPs)污染已引起全球关注。为了解鄱阳湖典型湿地微塑料的时空动态特征,相继于丰水期和枯水期采集鄱阳湖流域五河入湖段和鄱阳湖汇入长江出湖段的水体和沉积物样品,分别采用消解抽滤法和浮选分离-消解抽滤法分离水体和沉积物中的微塑料,采用显微镜、傅里叶变换红外光谱仪和扫描电镜鉴定分析微塑料表征。结果表明: 鄱阳湖各区域丰水期水体和沉积物微塑料丰度范围分别为32.1～127.3 n·L-1和533.3～1286.6 n·kg-1,枯水期分别为87.1～295.5 n·L-1和460.0～1368.0 n·kg-1,与其他淡水湿地相比,鄱阳湖具有较高的微塑料丰度,且各区域间呈时空差异性。研究区微塑料的主要形态有微球、碎片、薄膜和纤维等,相应聚合物成分主要为聚苯乙烯(PS)、聚丙烯(PP)和聚乙烯(PE)等;水体中微塑料以微球类(丰水期35.7%,枯水期52.0%)为主要形态,沉积物中以碎片类(丰水期45.8%,枯水期69.7%)为主要形态;两个水期水体和沉积物中均以小粒径(<0.1 mm)微塑料占优势(>50%),不同粒径微塑料丰度随粒径增大呈减少趋势。鄱阳湖湿地微塑料的潜在主要来源包括工业废水排放、城乡生活污水处理厂排放、农业和渔业活动以及生活垃圾处理不当。.
Keywords: Poyang Lake; microplastics (MPs); sediment; source; spatiotemporal dynamic; water body.