Pollution status and potential sources of main heavy metals in the main stream of the Yangtze River

In this study, we analyzed the pollution status and potential sources of heavy metals in the surface water of the main stream of Yangtze River. The results showed that the spatial distribution of metal concentrations from upstream to downstream of Yangtze River was significantly different, Cu, Zn and Al concentrations did not change significantly, Mn and Ni concentrations increased with fluctuation, while Cd and Pb concentrations increased and decreased with fluctuation. Heavy metal concentrations in the main stream of the Yangtze River increased compared with existing studies, which indicated the influence of human activities. However, the single-factor pollution evaluation showed that metals lightly polluted Yangtze River water and caused no carcinogenic and non-carcinogenic health risks to surrounding residents. The source analysis indicated that Cd, Pb and Ni may mainly be from industrial waste gas and wastewater, Al and Mn may be mainly derived from natural processes and mineral mining, Cu may be mainly derived from agricultural activities and mineral mining, Zn may mainly come from agriculture and industrial wastewater. Attention should be paid to the growing metal pollution of the main stream of Yangtze River because of anthropogenic activities.