南水北调中线工程调水前后汉江中下游干流水质变化特征

收集2013—2020 年汉江中下游区11 个典型断面水环境数据,采用单因子指数法、综合污染指数法以及水污染指数法,分析了南水北调中线工程调水前后11 个断面水质指标的变化特征及其成因。结果表明:调水后汉江中下游区11 个典型断面的月尺度污染指数呈不同程度的增大,其中罗汉闸和新沟闸污染较为严重;各断面的水质超标次数均增加,水体污染程度加重;TN 是汉江中下游各监测断面的主要污染物;TP、CODMn和NH3-N 水质污染自中游至下游沿程呈加重趋势,下游新沟闸断面污染最为严重。除受调水影响之外,汉江中下游水质变化还受到水利枢纽、点源和非点源污染等因素的综合影响。

Variation characteristics of water quality in middle and lower reaches of the Hanjiang River before and after Middle Route of South-to-North Water Diversion Project

The water quality data were collected at 11 typical sections in the middle and lower reaches of the Hanjiang River from 2013 to 2020. The single-factor index method, comprehensive pollution index method, and the water pollution index method were used to analyze the variation characteristics and causes of water quality indices at the 11 sections before and after water diversion. The results show that after water diversion, the monthly pollution indices of the 11 typical sections in the middle and lower reaches of the Hanjiang River increased in variant degrees, and the Luohanzha and Xingouzha sections were in the most severe water pollution. The frequency of water quality exceeding standards increased at all sections, with a deteriorated water pollution situation. TN was the dominant pollutant at each monitoring section in the middle and lower reaches of the Hanjiang River. Water pollution related to TP,CODMn and NH3 -N tended to deteriorate from the middle to the lower reaches. Water pollution at the Xinggouzha section was the most severe. In addition to the influence of water diversion, water quality variation was also affected by other factors such as the operation of water conservancy projects, point and non-point source pollution.