Distribution, Potential Sources, and Risks of Heavy Metal Contamination in the Huaihe River: Insights from Water and Sediment Analysis

Riverine heavy metal (HM) pollution, a critical global environmental issue, severely affects water quality, ecosystem health, and human well-being. The Huaihe River, once among China’s most polluted, has seen water quality improvements due to strict pollution controls, yet the extent of HM pollution reduction remains uncertain. Here, we investigated the distribution, sources, and potential ecological and health risks of nine typical HMs (Cr, Mn, Ni, Cu, Zn, As, Cd, Pb, and Hg) in surface water and sediment in the Anhui section of the river. Seasonal variations in HM concentrations were observed, with most values below drinking water safety limits, except for Mn and Cd at specific sites and seasons. Indices including the HPI, HEI, HQ, and HI showed low contamination and health risks, yet children are more vulnerable to non-carcinogenic hazards, notably from Cd and As. Sediment HMs trends decreased as Mn > Zn > Cr > Pb > Ni > Cu > As > Cd > Hg, with moderate pollution from Cd, Mn, and Pb based on CF, EF, and Igeo assessments. PLI and NPI suggested moderate ecological risks in midstream areas due to HM accumulation. The correlation analysis and PCA revealed that HMs in uncontaminated sediments were mainly of geogenic origin, while contaminated sediments were largely influenced by anthropogenic activities, including agricultural runoff, industrial waste, and domestic sewage discharge. Overall, our findings highlight that control of anthropogenic activities within the Huaihe River basin is essential for reducing HM pollution in the river.