Abstract
To assess the spatial distribution characteristics and health risk of heavy metals (Cu, Zn, Ni, Cd, Pb, and Cr) in surface sediment of the Hai River and its tributaries in Tianjin, China, 32 surface sediment samples were collected. All the heavy metals mainly occurred in residue, except Cd. Cd primarily existed in the exchangeable fraction and posed a high risk to the aquatic environment. The mean values of pollution index followed a decreasing trend of Cu > Cd > Ni > Pb > Cr > Zn. The results of health risk assessment showed that the heavy metals were not a threat to local residents and Cr and Pb were the main contributors to the health risk. The carcinogenic risk posed by Cr was two orders of magnitude higher than that posed by Cd. A self-organizing map divided the 32 sites into three clusters and more attention should be paid to cluster 3. The results will be conducive to understanding the heavy metal pollution patterns and implementing effective and accurate management programs.
Highlights
Every year, large amounts of contaminants are discharged into the aquatic ecological environment owing to the rapid global development of industries, agriculture, and urbanization (Zhang et al 2017a; Al-Ananzeh 2021)
We investigated the heavy metal concentrations in the surface sediments of the Hai River and its tributaries to (1) investigate the distribution and speciation of Cu, Zn, Ni, Cd, Pb, and Cr; (2) evaluate the heavy metal pollution levels using the Nemerow Pollution Index (Pn); (3) assess the human health risk posed by the heavy metals; and (4) determine the potential element correlations of the heavy metals in the surface sediment using a self-organizing map (SOM)
Heavy metal speciation is of great importance to their potential toxicity and mobility, and determining the chemical fractions is necessary for assessing the potential toxicity and identifying the sources (Xu et al 2017)
Summary
Large amounts of contaminants are discharged into the aquatic ecological environment owing to the rapid global development of industries, agriculture, and urbanization (Zhang et al 2017a; Al-Ananzeh 2021). Heavy metals enter the aquatic ecological environment from various natural (rock weathering, soil erosion, atmospheric deposition, volcanic eruption, and surface runoff) and anthropogenic (vehicle emissions, domestic sewage, industrial wastewater, agricultural fertilizer leachate, mining wastewater, and urban construction) sources (Wang et al 2020b). After heavy metals enter the aquatic ecological environment, they would cause irreparable harm to aquatic organisms and human health when they are above certain concentrations. The health risk assessment aims to reveal the correlation between human health and heavy metal pollution by relating each quantitative index to human health based on the three pathways (Zhang et al 2017c; Neris et al 2019). The human health risk assessment model suggested by the U.S Environmental Protection Agency (USEPA) uses the total heavy metal concentration to evaluate the health risks posed to people living in the area (Shil & Singh 2019)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
