祖厉河流域水质评价与时空变化分析

Water quality evaluation and spatial-temporal variation analysis in Zuli River Basin

祖厉河是黄河上游重要的一级支流,其水质状况直接影响到黄河干流水质。为了解祖厉河流域近年的水质状况,收集了7个监测断面2016—2020年的17个水质指标数据,使用单因子评价法、主成分分析法和综合污染指数法探究了祖厉河流域水质的时空变化特征。结果表明:(1)2016—2020年,祖厉河流域水体水质指标中氨氮、总磷、Cd、高锰酸盐指数、化学需氧量和粪大肠菌群存在超过《地表水环境质量标准》(GB 3838—2002)Ⅴ类标准限值的风险。(2)3种方法评价结果大体一致,下游因水量大、环境容量高、水体自净能力强而水质较好,上游因水量小、距离污水处理厂近而水质较差。(3)2016—2020年祖厉河流域水质状况逐年改善,2020年综合污染指数已达到清洁,水质较好状态;年内夏季相对较好,冬季相对较差。

Zuli River is an important first class tributary in the upper reaches of the Yellow River,and its water quality directly affects the water quality of the Yellow River.In order to understand the water quality status of Zuli River Basin in recent years,17 water quality indexes data of 7 monitoring sections from 2016 to 2020 were collected to explore the spatial-temporal variation characteristics of water quality by using single factor evaluation method,principal component analysis method and comprehensive pollution index method.Results showed that:(1)from 2016 to 2020,ammonia nitrogen,total phosphorus,Cd,permanganate index,chemical oxygen demand and fecal coliform had risk to exceed Class Ⅴ of“Environmental quality standards for surface water”(GB 3838-2002).(2)The results of the 3 methods were similar.The water quality of the lower reaches of the basin was relatively good due to huge water quantity,big environmental capacity,and strong water self-purification ability.That of the upper reaches of the basin was relatively bad due to small water quantity and close to wastewater treatment plant.(3)The water quality was improving year by year during the study period.Up to 2020,the comprehensive pollution index had become clean at a good state.In a year,the water quality was better in summer while worse in winter.