内蒙古河套灌区排水干沟微塑料赋存特征及质量估算

陆地径流中微塑料污染因其与人类联系更紧密已越来越受到人们的广泛关注，为分析内蒙古河套灌区排水干沟和总排水干沟微塑料的赋存特征并对其质量进行估算，通过现场采样、密度悬浮法分离、显微镜观察、傅里叶红外光谱测定和比例流量法等，鉴定了河套灌区排水干沟和总排水干沟水体和沉积物中微塑料的丰度分布、形状、颜色、粒径和化学成分，并估算了总排水干沟日输送微塑料的质量.结果表明，河套灌区排水干沟和总排水干沟水体中微塑料丰度值范围为2880~11200 n ·m^-3，沉积物中微塑料丰度值范围为100~292 n ·kg^-1；纤维状为最常见的微塑料形态，分别占据水体和沉积物的34.98%~70.39%和42.24%~58.56%；微塑料颜色以透明为主，分别占据水体和沉积物的46.43%~61.51%和40.41%~57.44%；微塑料粒径以<0.5 mm粒径最多，分别占据水体和沉积物微塑料的46.43%~61.51%和43.27%~54.79%；利用傅里叶红外光谱得出聚乙烯是最常见的类型（43%），其次是聚苯乙烯（34%）和聚丙烯（16%）；通过估算得出河套灌区总排水干沟每天可向乌梁素海排放的微塑料质量达到116.06 kg，并在乌梁素海积蓄后产生严重的微塑料污染效应.本研究可为内蒙古河套灌区微塑料的污染提供参考和借鉴.

Occurrence Characteristics and Quality Estimation of Microplastics in Drainage Ditches in Hetao Irrigation District of Inner Mongolia

Microplastic pollution due to land runoff has gained increasing attention as it is closely associated with human beings. In this study, we analyzed the occurrence characteristics of microplastics in drainage channel and main drainage channel in Hetao irrigation district of Inner Mongolia and estimated its quality. Through field sampling, the density separation of suspension method and microscope observation, Fourier infrared spectrum measurement, and proportional flow method, the abundance distribution, shape, color, particle size, and chemical composition of microplastics in the water body and sediment of the drainage channel and main drainage channel in the Hetao irrigation district were identified. The mass of microplastics transported in the main drainage channel was also estimated. The results showed that the value range of microplastic abundance in the water body of the drainage channel and the main drainage channel in Hetao irrigation district was 2880-11200 n ·m^-3, and the value range of microplastic abundance in the sediment was 100-292 n ·kg^-1. Fiber was the most common microplastic form, occupying 34.98%-70.39% and 42.24%-58.56% in the water and sediment, respectively. The color of microplastics was mainly transparent, which occupied 46.43%-61.51% and 40.41%-57.44% in the water and sediment, respectively. The largest particle size of microplastics was<0.5 mm, accounting for 46.43%-61.51% and 43.27%-54.79% in the water and sediment microplastics, respectively. It was concluded that polyethylene was the most common type (43%), followed by polystyrene (34%) and polypropylene (16%) using Fourier infrared spectroscopy. It was estimated that the main drainage channel in the Hetao irrigation district could transport 116.06 kg of microplastics into Lake Ulansuhai every day, and a serious microplastic pollution effect was generated due to the accumulation of microplastics in Lake Wulangsuhai. This study can provide reference for the pollution of microplastics in Hetao irrigation district of Inner Mongolia.