Author(s): Xiong Pan; Li Lin
Linked Author(s):
Keywords: No Keywords
Abstract: The study investigated the exposure levels and accumulation characteristics of five heavy metals -- Cu, Hg, Pb, Cd, and Cr -- in the water environment of the Three Gorges Reservoir area. It also evaluated their ecological risks. The findings reveal that from 2015 to 2017, the concentrations of As, Cd, Cr, Cu, and Pb in the main stream water met Class I water quality standards set by the Surface Water Environmental Quality Standard. However, Zn concentrations in certain river sections were classified as Class II water, especially higher in the upper urban river section due to exogenous input and sediment adsorption causing irregular fluctuations. The average metal element concentrations in sediments within the reservoir area slightly surpass the background values from the Yangtze River sediments. Cd in various periods and regions poses a moderate ecological risk, while the other five heavy metals present only slight risks. A 2022 investigation indicates significant and irregular fluctuations in the content of different heavy metals in surface sediments across various water periods. On average, Cd and Hg content remains almost unchanged between flood and non-flood seasons, while Pb increases during flooding and Cu and Cr decrease. When compared to data from 2015 to 2017, significant decreases were observed in Cu, Pb, and Cd contents in surface sediments, with Cr and Hg levels showing minor changes. Despite reductions, Cd content remains high in sediment, indicating a moderate ecological risk. Each heavy metal’s content fluctuates distinctly in the vertical direction without any specific pattern or noticeable enrichment.
Year: 2024