Risk assessment and sources associated with potentially toxic elements in suspended particulate matter: A karst river perspective in active mining area

Daiyang River Basin, a typical karst river basin impacted by mining activities in Guizhou, Southwest China. Rivers are fundamental components of regional water security, but they are facing potentially toxic elements (PTEs) pollution caused by mining activities. This study investigated the concentration, behavior, risks and sources of nine PTEs in suspended particulate matter (SPM) from mining-impacted karst rivers, which are essential for the safety and management of karst water environments. The contents of Cr, Ni, Cu, Zn, As, Cd, Sb and Hg exceeded the corresponding local soil background values, with Zn and Cu being the most important pollutants. These elements caused a very high potential toxicity risk to the basin and unacceptable carcinogenic and non-carcinogenic risks to the local residents. Correlation analysis and the positive matrix factorization (PMF) model indicated that Ni, Cd, Zn and Cu were mainly derived from mixed sources of geological background and anthropogenic activities (30.95 %), Hg, Sb, and As were related to coal mining and combustion sources (28.91 %), while Pb, As, Cr and Sb were mainly contributed by natural sources (40.15 %). Furthermore, mixed sources, mining-related sources and As were identified as priority control factors in the study area. These insights can provide powerful support for decision-makers to develop control policies and reduce PTEs pollution in karst areas. • Karst rivers in mining areas are found to be markedly contaminated with PTEs in SPM. • PTEs in karst rivers of mining areas pose significant toxicity risks to aquatic organisms. • Carcinogenic and non-carcinogenic risks of PTEs in SPM found to endanger children and adults. • Mixed sources, mining-related sources and As were identified as priority control factors in karst mining areas. • Targeted control measures and long-term monitoring are essential for karst mining area rivers.