Spatial-Temporal Distribution, Risk Assessment, and Source Identification of Dissolved Heavy Metals in the Panzhihua Section of Jinsha River, Southwest China

The Jinsha River (Panzhihua section) in China, a crucial water source for the Yangtze River, has been severely impacted by human activities. In this study, water samples were collected from 21 crucial locations in the Jinsha River (Panzhihua section) during the wet and dry seasons to investigate the sources and distribution of dissolved heavy metals. The concentrations of these heavy metals displayed significant temporal and spatial heterogeneity, with higher concentrations in the dry season. The uneven distribution of human activities along the river led to variations of these trace elements. Furthermore, the average concentrations of these heavy metals, except Mn, surpassed the background values of the Jinsha River but fell below the permissible limits recommended by the drinking water guidelines of China, WHO, and USEPA, except for V.Multivariate statistics results revealed three principal components accounting for 67.25% of the total variance. The smelting of vanadium-titano magnetite significantly contributed to V and Cu in the Jinsha River. Vehicle emissions and smelting were identified as the primary sources of Cd, Pb, and Cr in the Jinsha River, while coal combustion was found to be the main source of Mn and Ni. The water quality index ranged from 1.7 to 18.8 for the wet season and from 5.1 to 20.4 for the dry season, revealing that Jinsha River (Panshihua section) is safe for drinking. The Hazard Quotient and Index (HQ/HI) are all < 1, implying that the heavy metals studied in the Jinsha River pose minimal to no health risks through oral consumption or skin contact. Nevertheless, the hazard indices for the heavy metals V and Cr are still relatively high, posing a potential risk to human health. Hence, it is essential to take specific actions to prevent heavy metals from entering the Jinsha River to protect its excellent water quality.