Assessment and sources of heavy metals in the suspended particulate matter, sediments and water of a karst lake in Guizhou Province, China

An integrated assessment of heavy metal (HM) contamination in dissolved matter, suspended particular matter (SPM) and sediments in lakes is essential. This study assessed the risks of HMs in the water, SPM and sediment of Caohai, China, and analyzed the changes in sediment HM contamination in conjunction with historical data. The HM transport was dominated by the SPM load, and the concentrations of Zn (179.07-1821.24 mg kg (1)), Pb (53.63-181.46 mg kg (1)), and Cd (3.68-21.31 mg kg(-1)) in SPM and sediment were 5.34-149.11 times higher than the upper continental crust (UCC) values. SPM and sediments were lightly to extremely polluted and had moderate to very high toxicity risks with Cd, Pb and Zn, and these three HMs originated from industrial and agricultural sources. The concentrations of Zn, Pb, and Cd in Caohai sediments increased by 36.7-187.9 % in 2022 compared to pre-2020. This research provides valuable reference data for the remediation of polluted karst lakes.

Automated summary

It is essential to assess the contamination of heavy metal (HM) in lakes in dissolved matter, suspended particular matter (SPM), and sediments. This study evaluated the risks of HMs in Caohai, China, in water, SPM, and sediment, and analyzed the changes in sediment HM contamination with historical data. The transport of HM was mainly influenced by SPM load, and the concentrations of Zn, Pb, and Cd in SPM and sediment were significantly higher than the upper continental crust (UCC) values. SPM and sediments were polluted and had high toxicity risks, originating from industrial and agricultural sources. The concentrations of Zn, Pb, and Cd in Caohai sediments showed an increase compared to previous years. This research provides valuable reference data for the remediation of polluted karst lakes.