Abstract
Accumulated heavy metals in surface sediments are released into the aquatic environment, causing secondary contamination of the hydrosphere, and increasing the risks to human health. To evaluate the pollution characteristics of heavy metals in the sediments of the Chishui River Basin, in the present study, the concentrations of five heavy metals in surface sediments of the Chishui River Basin in China were investigated using the geo-accumulation index, pollution load index, and potential ecological risk indexes. These indexes evaluated the degree of contamination and the influence of human activities on heavy metal levels in the basin. Cu, Zn, Cd, Hg, and As were found at concentrations of 5.12-120.40, 36.01-219.31, 0.03-1.28, 0.01-1.18, and 1.56-11.59 mg kg-1, respectively, with mean values of 37.43, 91.92, 0.25, 0.07, and 5.16 mg kg-1, respectively, in the order Zn > Cu > As > Cd > Hg. The contamination indices revealed Hg as the principal pollutant based on the spatial distribution, while Pearson's correlation coefficients suggested that Cu, Zn, and As originated from a similar source. Hg had a different source from the other metals, whereas Cd originated from a different source compared with that of Zn, As, and Hg. This paper showed a Hg and Cd contamination in the Chishui River Basin.
Highlights
Contaminants containing high concentrations of heavy metals continue to be discharged into aquatic systems
The Chishui River (104 ̊450–106 ̊510 E, 27 ̊200–28 ̊500 N) in southwest China is located at the transitional zone between the Yunnan-Guizhou Plateau and the Sichuan Basin (Fig 1)
32 sediment samples were collected in the whole Chishui River basin, 19 sites were on the main stream and the other 13 sites were on the tributaries, which basically covered the entire basin of the Chishui River. 1–8 sampling sites were located at upstream, sites 9–16 were distributed in the middle stream and sites 17–24 were at downstream
Summary
Contaminants containing high concentrations of heavy metals continue to be discharged into aquatic systems. These metals are often deposited on the bottom of such systems via precipitation and flocculation, thereby transforming the associated sediments into heavy metal repositories [1,2,3]. Due to their non-degradability, toxicity, and resistance to metabolization [4,5], heavy metals in sediments can harm aquatic organisms, as well as human health, through bioaccumulation and bioamplification [6].
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