Distribution, ecological risk, and source analysis of heavy metals in sediments of Taizihe River, China

Heavy metal contaminants can enter the water system through the hydrological cycle, after a period of flocculation and sedimentation, and finally accumulate in the sediments of the receiving water body. Sediment samples were collected along the Taizihe River, the concentration and ecological risks of Zn, Cu, Pb, Cr, As, and Cd were detected and evaluated, and the pollution sources was analyzed through principal components analyses. The results indicated that As, Pb, and Cd were the main heavy metal contaminants in the sediment from Taizihe River, and all the monitored sites in the wet and dry season exceed PEC value. In addition to Zn, the average concentrations of the rest of the heavy metals in the dry season were higher than that in the wet season, and most of the heavy metals showed a certain accumulation tendency from upstream to downstream. The level order of potential ecological risk was Cd > As > Pb > Zn > Cu > Cr, and the risk in dry season was higher than that in wet season. Among them, As, Cd, and Pb had the highest single potential ecological risk coefficient (Eri\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$E_{{\text{r}}}^{i}$$\end{document}), which occupied the dominate position of total risk. The potential ecological risk of most heavy metals in the dry season was higher than that in the wet season. The sources of heavy metal pollution in the sediments of the Taizihe River in different periods were the same, mainly from industrial pollution, especially from the petrochemical, electroplating industries, and mining. The heavy metal pollution in the Taizihe River was located in the middle and lower reaches of the cities, and has a certain relationship with the factories in the lower reaches of nearby city. During the dry season, the contribution rate of industrial pollution sources to heavy metals was more significant.