黄河呼和浩特段水环境质量时空变化分析

水环境质量评价是水资源可持续利用的重要前提，同时也是水环境管理与治理决策的重要依据。为科学评价黄河呼和浩特段水环境质量，基于基础资料数据库，遵循全面性、区域性、易量化性等原则，采用综合污染指数法详细分析了黄河呼和浩特段水环境质量的时空变化情况，进一步揭示了2020年水质季节变化规律，并对主要超标因子进行了深度解析。结果表明：随着一系列环境保护政策和管理措施的实施，2015—2020年黄河呼和浩特段水环境质量综合指数下降了75.87%。在时间尺度上，各断面的水环境质量综合指数平均值由2015年的93.81下降至2020年的22.64,整体水环境质量评价等级由G4转为G2,对应的水环境质量状况由中度污染转为较好；在空间尺度上，上游水环境质量优于下游，城区段水环境质量较差。此外，评价结果显示，部分水体当前仍存在氨氮超标问题。评价结果较为客观地反映了黄河呼和浩特段的水环境质量，可为水环境管理提供决策依据。

Spatial-Temporal Variation Analysis of Water Environment Quality in Hohhot Section of the Yellow River

The quality assessment of water environment is a crucial process for the sustainable utilization of water resources and also one of the important base for the water environmental management and the relative governance decisions formulation.To assess water environment quality in Hohhot section of the Yellow River,based on the databank of the water quality index,following the principles including comprehensiveness,regionality and easy quantification,the comprehensive pollution index method was employed to analyse the water environment quality in the spatial-temporal dimension in detail.Moreover,the seasonal change rule of water environment quality in Hohhot section of the Yellow River in 2020 also was revealed,and exceeding factors were deeply analysed.The results showed that the comprehensive water environmental quality index dropped by 75.87% between 2015 and 2020 with the implementation of the relative environmental protection policies and river chief system issued.In the view of temporal variation,the average of the comprehensive water environment quality index had decreased from 93.81 in 2015 to 22.64 in 2020,indicated that the water environment quality was improved from moderate pollution to good.In the view of spatial variation,the water quality in of river upstream was better than that river downstream,and the water quality in the urban was poor.In addition,the results showed that there are still problem with ammonia nitrogen exceeding the standard,currently.These results reflect the water environment quality of Hohhot section of the Yellow River and may provide decision-making basis for water environment management.