宜昌市东山运河微塑料污染评估及年排放量估算

微塑料作为一种新兴的污染物受到世界的广泛关注.城市是微塑料污染产生的重点区域，而城市水体则是微塑料向其他淡水环境传输的重要载体.以宜昌市城区东山运河为研究对象，于2022年7月和10月分别通过现场采样、显微镜观察和傅里叶红外光谱测定等方法，鉴定和分析了东山运河水体中微塑料的赋存特征和潜在污染来源，并依据风险指数（H）、污染负荷指数（PLI）模型和比例流量法定量评估了水体中微塑料的生态风险和年排放量.结果表明，东山运河表层水中微塑料的平均丰度为（7 295±1 051） n·m^-3（7月）和（5 145±762.6） n·m^-3（10月）；其中，纤维状（27.63%~63.23%）、尺寸<0.5 mm（75.68%~96.2%）和彩色（22.73%~61.83%）的微塑料占据主导地位，材质以PE（30.1%）和PET（26.33%）为主；两种模型的评估结果显示，东山运河生态风险指数属于Ⅲ类，总体污染负荷属于Ⅰ类，部分点位污染负荷达Ⅱ类；通过估算得出东山运河每年向长江输送微塑料约3.37 t.总体而言，宜昌市东山运河微塑料污染程度属于中等，其污染来源可能是洗衣废水、个人护理产品和塑料废弃物等.

Assessment of Microplastic Pollution and Estimation of Annual Emission Volume in the Dongshan Canal of Yichang City

Microplastics, as an emerging pollutant, have garnered global attention. Urban areas are key hotspots for the generation of microplastic pollution, whereas urban water bodies act as vital conduits for the dissemination of microplastics to other freshwater environments. In this study, the Dongshan Canal in the urban area of Yichang City was selected as the research subject. Through field sampling, microscopic observation, and Fourier infrared spectroscopy analysis conducted in July and October 2022, the occurrence characteristics and potential pollution sources of microplastics in the water body of the Dongshan Canal were identified and analyzed. The ecological risk and annual emission volume of microplastics in the water body were quantitatively assessed using the risk index (H), pollution load index (PLI) model, and proportional flow method. The results indicated that the average abundances of microplastics in the surface water of the Dongshan Canal were (7 295±1 051) n·m^-3 (July) and (5 145±762.6) n·m^-3 (October). Fibrous microplastics (27.63%-63.23%), microplastics with a size of <0.5 mm (75.68%-96.2%), and colored microplastics (22.73%-61.83%) dominated the samples, with PE (30.1%) and PET (26.33%) being the predominant materials. The assessment results from the two models classified the ecological risk index of the Dongshan Canal as class Ⅲ, whereas the overall pollution load fell into class I, with certain sampling points reaching class Ⅱ. Estimates revealed that the Dongshan Canal transports approximately 3.37 t of microplastics to the Yangtze River annually. Overall, the microplastic pollution level in the Dongshan Canal of Yichang City could be considered moderate, with potential sources of pollution including laundry wastewater, personal care products, and plastic waste.