Occurrence, source apportionment, and ecological risk of potentially toxic elements in an urban shallow lake sediment

This study evaluated the occurrence, spatial distribution, source, and ecological risk of potentially toxic elements (PTEs) in the sediment of an urban shallow lake in a mid-sized city. The ecological risk indices, enrichment factor (EF) and geoaccumulation index (Igeo) indicated high enrichment and contamination with Cd and moderate enrichment with Ni and Hg, while the potential risk index (RI) showed a moderate ecological risk. The mean contributions of individual PTE species to the total risk were in the following order: Cd > Hg > Ni > As > Cu > Pb > Cr > Zn. The sediment quality guideline (SQG) indices revealed that biological effects might occur occasionally due to the Cd and Ni contamination and a low or relatively insignificant risk of adverse biological effects from other PTEs. There were moderate to strong positive inter-metal relationships that suggested their common sources. The primary source responsible for elevated PTE concentrations was the traffic-related discharge. The main contributors to ecological risks were Cd and Ni. These findings highlight the importance of paying attention to the ecological environment of urban shallow lakes, which are particularly sensitive to their surroundings.