沁河(焦作段)入河排污水体微塑料污染特征及风险评价

Pollution characteristic and risk assessment of microplastics from sewage outlets in the Qin River(Jiaozuo section)

河岸排污是引起河流水环境微塑料升高的主要途径。摸清沿河两岸排污水体中微塑料的赋存特征及其环境风险,是进行微塑料污染控制的前提。以黄河支流沁河(焦作段)为研究对象,采集7个入河排污口的污水样品,采用体视显微镜对微塑料丰度和形貌特征(包括尺寸、形状及颜色等)进行分析,发现微塑料在所有样点均有检出,尺寸为500~2 000μm,颜色以透明和蓝色为主,纤维状是微塑料在各个样点的主要形状。进一步借助显微红外光谱仪对各样点污水中的聚合物类型进行了鉴定,结果显示排污口水体中微塑料种类以聚乙烯为主,其可能与周边区域的农业生产和居民生活排放有关。环境风险评价结果表明,研究区段整体处于低风险水平;排污口微塑料引起的环境风险不仅与其丰度有关,还依赖于微塑料的种类,有聚氯乙烯检出的样点1和6均呈现较高的环境风险。该研究结果可为黄河及其支流微塑料风险防控提供参考。

Wastewater discharge is the major source of microplastic pollution in river.Identification of the characteristics of microplastics and their environmental risks in the discharged waters along sides of river is a prerequisite for microplastic pollution control.The Qin River(Jiaozuo section),a tributary of the Yellow River,was selected as the research object and a total of 7 water samples were collected from sewage outlets.The abundance and morphological features of microplastics,including size,shape and color,were classified by using a stereomicroscope.Microplastics were found in all sample sites,and the sizes varied mainly between 500 and 2000μm.In addition,the colors were mainly transparent and blue,and fibrous was the main shape of microplastics at each sample point.Further,the types of polymers at all points were identified using microinfrared spectrometry.The results showed that the main type of microplastics in the sewage outlets was polyethylene,which mainly came from agricultural production and residential emissions in the surrounding areas.The results of the environmental risk assessment showed that the study area was at a low risk level overall.The environmental risk posed by microplastics at the outfalls was not only related to its abundance,but also depended on the type of microplastics.Sample sites 1 and 6 both presented higher environmental risks as polyvinyl chloride was detected.Research results could provide theoretical basis and data support for the prevention and control of microplastic risks in the Yellow River and its tributaries.