2010—2019年黄河干流兰州和白银段水质时空变化特征

基于综合污染指数法，结合单因子污染指数法及累积距平法等多种统计分析方法，定量分析了黄河流域兰州和白银段7个监测断面水质时空变化特征。结果表明:兰州段和白银段2010—2019年水质综合状况良好，各监测断面综合污染指数均在0.25以下；监测断面水质空间差异显著(P<0.05)，兰州段整体水质优于白银段，扶和桥断面水质显著优于除新城桥外的其他断面(P<0.05)；季节方面，兰州段综合污染指数在春、冬季高于夏、秋季(P<0.05)，白银段水质季节性波动不明显；兰州段水质明显改善始于2014年，且经历了综合污染指数平稳下降(2014—2017年)和快速下降(2018—2019年)两个阶段；白银段水质发生转变时间滞后于兰州段(2016年)，2017—2019年水质明显好转。

Temporal and spatial variation characteristics of water quality in Lanzhou and Baiyin section of the Yellow River mainstream from 2010 to 2019

Based on the comprehensive pollution index method, combined with single factor pollution index method, cumulative anomaly method and other statistical analysis methods, the temporal and spatial variation characteristics of water quality of 7 sections in Lanzhou and Baiyin section of the Yellow River mainstream were quantitatively analyzed. The results show that the comprehensive water quality of Lanzhou and Baiyin sections was good from 2010 to 2019, and the comprehensive pollution indexes of each section were all below 0. 25. The water quality of each section had significant spatial difference(P<0. 05)and the overall water quality of Lanzhou section was better than Baiyin section. The water quality of Fuhe Bridge section was significantly better than other sections except Xincheng Bridge(P<0. 05). In terms of season, the comprehensive pollution indexes of water quality in spring and winter were higher than those in summer and autumn(P<0. 05)in Lanzhou section while the seasonal fluctuation of water quality in Baiyin section was not obvious. The water quality of Lanzhou section notably improved from 2014 and experienced two periods including the stable decline period of comprehensive pollution index(2014-2017)and rapid decline period of comprehensive pollution index(2018-2019). The water quality change time of Baiyin section lagged behind Lanzhou section(2016)and the water quality improved significantly from 2017 to 2019.