Distribution and risk assessment of heavy metals in overlying water, porewater, and sediments of Yongding River in a coal mine brownfield

Purpose Heavy metals from coal mines migrate into rivers and cause a severe impact on the health of local residents utilizing these rivers as a water source. However, current studies on coal mine brownfields have yet to thoroughly investigate river-associated heavy metals produced by coal mining. Therefore, this study aims to explore the distribution and risk assessment of heavy metals, namely Cr, Cu, Mn, Ni, Pb, and Zn, in overlying water, porewater, and sediments of the Yongding River, China.