The distribution characteristics of heavy metals and Pb isotopes in the sediments of the Fuhe River, South China: Implication for anthropogenic influences

Fuhe River is the second largest river that flows into Poyang Lake, the largest freshwater lake in China. With rapid socioeconomic development, heavy metal pollution in its sediments has become increasingly severe. To clarify the distribution and sources of heavy metals in the Fuhe River Basin, sediment samples were collected from the mainstream and major tributaries in July 2021, and the contents of Cr, Mn, Ni, Cu, Zn, Cd, Pb, U, Zr and Pb isotopes in the sediments were measured. Results showed that Zr, U, and Cd contents were higher in the upper reaches; Cr was highest in the lower reaches and Ni, Cu, Zn and Pb contents peaked at the estuary of the Yihuang River (a tributary). The analyses of the multivariate statistical methods (MVSM), including Absolute Principal Component Score-Multiple Linear Regression and Positive Matrix Factorization, principal component analysis and correlation analysis, revealed that Mn, Cu, Zn and Pb were mainly from industrial activities, Cd, U and Zr were from natural rock weathering, Cr came from agricultural activities, and Ni originated from the combined pollution of industry and agriculture. Pb isotope signal highlighted that Pb in the sediments was mainly associated with industrial activities. The Pollution Load Index highlighted the most severe pollution at this estuary, while the Geo-accumulation Index indicated prominent Cd pollution (twice the background value). The Potential Ecological Risk Index and Human Health Risk Assessment Model indicated that the risks of sediments in the middle reaches are greater. These findings help to deeply understand the cycle of river pollutants and are also helpful for the treatment of river pollution.