Abstract
Heavy metal pollution in sediment is one of the most serious problems in water bodies, including rivers, which can cause secondary pollution when environmental conditions change. In this study, surface sediment samples collected from the four main tributaries of Dongting Lake (i.e., Xiangjiang River (XR), Zishui River (ZR), Yuanjiang River (YR), and Lishui River (LR)) were analyzed for concentrations of Zn, Cr, Cu, As, Cd, and Pb. The spatial distribution, source, and potential ecological risk of these metals were determined. The results suggest a great spatial heterogeneity of heavy metals in the sediment of the studied rivers. Heavy metals had highest concentrations in the sediment of XR, especially midstream and downstream. A principal component analysis (PCA) and correlation analysis indicated that Cd and As were mainly from industrial wastewater and mineral mining, Cr came from natural process and agricultural activities, and Zn and Cu potentially from both. Pb was originated from atmospheric deposition and river inflow transportation. According to the geo-accumulation index ( I g e o ), enrichment factor (EF), and risk index (RI) assessment, heavy metals pollution was highest in the sediment of XR, and Cd was the main pollutant in the sediment of XR, presenting considerable potential ecological risk. This may contribute to heavy metal pollution in Dongting Lake. This paper provides a reference for the aquatic environmental management of heavy metals in Dongting Lake area and its tributaries.
Highlights
Aquatic systems enable hydrological cycling, climate regulation, and habitat provision for aquatic organisms
Some studies compared the heavy metal concentration in the sediment of Dongting lake and the river inlets, the results indicated that the heavy metal concentration in the sediment of the inlet of the four rivers is higher than other parts of Dongting Lake [55]
The identification and quantification of heavy metal pollution in the sediment of tributaries in Dongting Lake is of great importance for the maintenance of a healthy ecosystem
Summary
Aquatic systems enable hydrological cycling, climate regulation, and habitat provision for aquatic organisms. Heavy metal pollution in the aquatic environment has attracted global attention because of the environmental toxicity, persistence, and bioaccumulation of heavy metals, which can pose adverse effects on living beings and the entire ecosystem [1,2]. About 99% of the heavy metals load in aquatic systems has been found to precipitate onto the sediment [5]. Heavy metal concentrations in the sediment are usually four or five times higher than that found in the overlying water [6]. It is of great importance to measure the amount of heavy metals in the sediment to provide information on the heavy metal contamination of the entire aquatic ecosystem. The Cd values in the midstream (22.04 mg/kg) and downstream (18.84 mg/kg) regions were more than 11- and 9-fold higher than the upstream (2.02 mg/kg), respectively. The heavy metals were present at a higher concentration midstream and downstream of LR, with the exception of
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