Ecological risk characteristics of sediment-bound heavy metals in large shallow lakes for aquatic organisms: The case of Taihu Lake, China

• Published in: Journal of environmental management 2023-09, Vol.342, p.118253-118253, Article 118253
• Main Authors: Zhang, Shaoxuan, Zeng, Xia, Sun, Ping, Ni, Tianhua
• Format: Article
• Language: English
• Subjects: Aquatic Organisms; Cadmium; China; Ecological risk assessment; Environmental Monitoring; Geologic Sediments; Heavy metal; Humans; Lakes; Lead; Metals, Heavy - analysis; Risk Assessment; Species sensitivity distributions; Surface sediments; Taihu lake; Water Pollutants, Chemical - analysis
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2023.118253

Heavy metal contamination in the surface sediments of large shallow lakes in China is becoming increasingly serious. However, more attention has been paid to the human health risk of heavy metals in the past, while little consideration has been given to aquatic organisms. Taking Taihu Lake as an example, we explored the spatial and temporal heterogeneity of the potential ecological risks of seven heavy metals (Cd, As, Cu, Pb, Cr, Ni, and Zn) to species at different taxonomic scales using an improved species sensitivity distribution (SSD) method. The results showed that all six heavy metals, except Cr, were exceeded to some extent compared to background levels, with Cd being the most severe exceedance. Based on the hazardous concentration for 5% of the species (HC5), Cd had the lowest HC5 value, implying the highest ecological risk of toxicity. Ni and Pb had the highest HC5 values and the lowest risk. Cu, Cr, As and Zn were at a relatively moderate levels. For the different groups of aquatic organisms, the ecological risk of most heavy metals was generally lower for vertebrates than for the whole species. The risk for invertebrates and algae was higher than that for all species. Zn and Cu had the highest potentially affected fractions (PAFs) for all classification cases, with mean PAFs of 30.25% and 47.2%, respectively. Spatially, the high ecological risk of sediment heavy metals was significantly related to the spatial characteristics of the type and intensity of human activities in the catchment. Administratively, the environmental quality standards for freshwater sediments proposed by America and Canada are insufficient to protected against the ecological risks of heavy metals in Taihu Lake. In the absence of such standards, China urgently needs to establish an approptiate system of environmental quality standards for heavy metals in lake sediments. [Display omitted] •Cd poses the highest eco-risk to aquatic organisms, with 95% of species protected.•Invertebrates and algae in shallow lakes are at higher eco-risk of heavy metal.•Zn and Cu have the highest potentially affected fractions on aquatic organisms.•The eco-risk of heavy metals is spatially linked to coastal human activities.•Existing enviro criteria are of limited use in preventing eco-risks of heavy metals.