Abstract:

Microplastic pollution in river waters has attracted widespread attention at home and abroad, but there are relatively few studies on microplastic pollution in multi-environmental media in urban drainage rivers that has significant influences on human activities during different water periods. In order to reveal the distribution pattern of microplastics in urban drainage channels, this paper took the water bodies of Beijing’s Beiyun River as an example. Based on the surface water, sediment and fish samples of the Beiyun River during flood and non-flood periods, the paper analyzed and summarized the spatial and temporal distribution characteristics of different types of microplastics, discussed the differences in composition characteristics and revealed the main sources of microplastics in the Beiyun River. The results showed that the abundance of microplastics in the surface water of the Beiyun River ranged between 4.9-22.1 items∙L⁻¹ (flood) and 3.10-14.8 items∙L⁻¹ (non-flood); the abundance of microplastics in the sediment ranged between 0.74×10³-2.88×10³ items∙kg⁻¹ (flood) and 0.16×10³-1.69×10³ items∙kg⁻¹ (non-flood); abundance of microplastics in the fish gut ranged between 0.33-3.33 items∙ind⁻¹. In comparison with other rivers at home and abroad, microplastic pollution in water and sediment in the Beiyun River was at a moderate level, with a low level of microplastic pollution in fish. On the temporal dimension, the abundance of microplastics in both surface water and sediment was greater in the flood season than in the non-flood season. On the spatial dimension, the abundance of microplastics in surface water was greater in the country section than in the urban section during the flood season, and in the non-flood season, it was greater in the urban section than in the country section, and the abundance of microplastics in sediments did not show significant correlation between different water periods. Surface water was dominated by less than or equal to 0.5 mm clear/white polyethylene and polypropylene fibers, sediment was dominated by less than or equal to 0.5 mm clear/white polyethylene/ polypropylene fragments, and fish were most abundant in less than or equal to 0.5 mm blue cellulose fibers. The abundance of microplastics in the gut of omnivorous fish was significantly higher than that of carnivorous, and the perched water layer had less influence on the abundance of microplastics in the gut of fish. The main sources of microplastics in the Beiyun River are human daily life, tourism, fishing activities and sewage discharge. The results of the study can provide baseline data for the study of microplastic pollution in urban rivers and provide a reference for the control and prevention of microplastic pollution.

Key words: microplastics, Beiyun River, water, sediment, fish, distribution characteristics

摘要：

河流水体的微塑料污染已引起国内外的广泛关注，但对人类活动影响显著的城市排水河道不同水期多环境介质中的微塑料污染研究相对较少。为揭示城市排水河道微塑料分布规律，以北京市北运河水体为例，基于汛期和非汛期北运河表层水、沉积物和鱼类样品，分析统计了不同种类微塑料的时空分布特征，讨论了组成特征差异，揭示了北运河微塑料的主要来源。结果表明，北运河表层水中微塑料丰度为4.90－22.1 items∙L⁻¹（汛期）和3.10－14.8 items∙L⁻¹（非汛期）；沉积物中微塑料丰度为0.74×10³－2.88×10³ items∙kg⁻¹（汛期）和0.16×10³－1.69×10³ items∙kg⁻¹（非汛期）；鱼类肠道内微塑料的丰度为0.33－3.33 items∙ind⁻¹。与国内外其他河流对比，北运河水体和沉积物的微塑料污染处于中等水平，鱼类微塑料污染程度较低。时间尺度上，表层水和沉积物中微塑料丰度均表现为汛期>非汛期。空间尺度上，汛期表层水的微塑料丰度表现为郊野段>城市段，非汛期表现为城市段>郊野段，不同水期沉积物微塑料丰度未显示显著的相关性。表层水以≤0.5 mm透明/白色聚乙烯和聚丙烯纤维为主导，沉积物以≤0.5 mm透明/白色聚乙烯/聚丙烯碎片为主导，鱼类中≤0.5 mm蓝色纤维素纤维最为丰富。杂食性鱼类肠道内微塑料的丰度显著高于肉食性，栖息水层对鱼类肠道内微塑料的丰度影响较小。北运河微塑料主要来源为人类日常生活、旅游业、渔业活动和污水排放。研究结果可为城市河流的微塑料污染研究提供基础数据，并为微塑料污染的管控和防治提供参考。

关键词: 微塑料, 北运河, 水体, 沉积物, 鱼类, 分布特征