石嘴山典型入黄排水沟水质时空变化特征及驱动因素

Spatiotemporal variation characteristics and driving factors of water quality in Shizuishan section of typical drainage ditches flowing into the Yellow River

为确保入黄排水沟水质稳定达标,实现黄河流域生态保护及高质量发展,应用WQI-DET指数和水质主成分分析指数(PCAI)两项综合水质指标分析了宁夏入黄第三与第五排水沟石嘴山段2020—2022年水质时空变化特征,并结合曼特尔检验和事后多重比较法从自然因素与人类因素两方面探究了排水沟水质变化驱动因素。结果表明:排水沟贺兰段断面水质达标率最低(第三排水沟57.6%,第五排水沟69.4%),第三排水沟污染源多,治理难度大,第五排水沟污染源少,水质稳定;农田退水污染主要发生在灌溉前期,灌溉中期与冬灌期的农田退水可对河道起净化作用;第五排水沟灌溉前期多项指标与其他时期存在显著差异(p<0.05);自然因素对排水沟水质无显著影响,当地污染源以生活污水和工业废水为主。

In order to ensure the water quality of drainage ditches flowing into the Yellow River to reach the standard and achieve ecological protection and high-quality development of the Yellow River Basin,the water quality index-development(WQI-DET)and principal component analysis index(PCAI)of water quality were used to analyze the spatiotemporal change characteristics of water quality from 2020 to 2022 in the Shizuishan section of the Third and Fifth Drainage Ditches flowing into the Yellow River.Mantel tests and multiple comparisons were employed to explore the driving factors influencing water quality in the drainage ditches,considering both natural and human factors.The results show that the compliance rate for water quality in the Helan section of the drainage ditches is the lowest(57.6%in the Third Drainage Ditch and 69.4%in the Fifth Drainage Ditch).Pollution sources are numerous in the Third Drainage Ditch,making it difficult to manage,while pollution sources are fewer in the Fifth Drainage Ditch,leading to more stable water quality.Irrigation water pollution mainly occurs in the early period of irrigation,while agricultural runoff during the mid-irrigation and winter irrigation periods can have a purifying effect on the river.Many indexes of the Fifth Drainage Ditch vary significantly between the early period of irrigation and other periods(p<0.05).Natural factors have no significant effect on the overall water quality of the drainage ditches,and the local pollution sources are mainly domestic sewage and industrial discharge.