Contamination and Risk of Heavy Metals in Sediments from Zhuzhou, Xiangtan and Changsha Sections of the Xiangjiang River, Hunan Province of China

Abstract

This study focuses on the riverbed sediments in the Changsha-Zhuzhou-Xiangtan (CS-ZZ-XT) section of the lower reaches of the Xiangjiang River. Principal element analysis, ecological risk analysis, and early warning methods were used to explore the distribution pattern and risk assessment of various chemical elements in the sediments. The results indicated that the vertical distributions of Sc, Co, Th, and U were more homogeneous, while Cr, V, Cu, and Ni distributed heterogeneously with significant changes. Risk assessment of heavy metals was explored by using the Geoaccumulation index, potential ecological risk index, and ecological risk index, suggesting that the contamination levels followed: ZZ > XT > CS. ZU and ZX points in the ZZ section exhibited the higher ecological risk. The ecological risk of heavy metals followed the order of: Pb > Cu > Zn > Ni > Co > Mn > V > Cr, and the contamination of Cd and Mn was located at the severe warning condition. Additionally, it was suggested that Th, U, Pb, Zn, Cu, and Mn mostly originated from both anthropogenic activities and natural processes, while Ni, Cr, Co, V, Sc, and Ba were derived from natural processes. Therefore, the contamination of Cd, Th, U, Pb, Zn, Cu, and Mn, especially Cd and Mn, should be considered by the environmental protection strategies in the studied watershed.