Sun Haoran, Gao Bo, Gao Li, Xu Dongyu, Sun Ke
State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China; State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China.
Sci Total Environ. 2019 Jul 1;672:192-200. doi: 10.1016/j.scitotenv.2019.03.400. Epub 2019 Mar 28.
As one of the largest man-made reservoir, the Three Gorges Reservoir (TGR) brings great uncertainty and challenges regarding trace metal (e.g., Cu) remobilization in the sediment. Therefore, in this study, sediment cores were collected from the mainstream of the Yangtze River and its three tributaries in the TGR, with a focus on evaluating the Cu remobilization risk and release dynamics using conventional methods, diffusive gradients in thin films (DGT), and the DGT-induced fluxes in sediments (DIFS) model. The results showed that although total Cu concentrations were slightly higher than background values, Cu was mainly observed in the unreactive residual fraction. Additionally, assessment of sediment quality guidelines and the risk assessment code indicated low Cu contamination risk for all sampling sites. However, the results of DGT measurements at the sediment-water interface showed efflux of Cu from sediment to the overlying water at most sites, except for the upstream of the Meixi River and the mainstream of the Yangtze River. Interestingly, diffusion fluxes at the three tributaries displayed an increase trend from the upper to lower reaches. The DIFS model simulation further implied that the highest resupply capacity and desorption rate occurred in the Zhuyi River and the upstream of the Meixi River. In fact, the accumulation of Cu from the upper to the lower reaches of the Zhuyi River significantly elevated the Cu resupply capacity. Thus, more attention should be paid to Cu mobilization in the TGR, especially in the Zhuyi River and the upstream of the Meixi River.
作为最大的人工水库之一，三峡水库（TGR）给沉积物中痕量金属（如铜）的再迁移带来了极大的不确定性和挑战。因此，在本研究中，从长江干流及其在三峡水库的三条支流采集了沉积物岩芯，重点是使用常规方法、薄膜扩散梯度（DGT）和沉积物中DGT诱导通量（DIFS）模型评估铜的再迁移风险和释放动态。结果表明，尽管总铜浓度略高于背景值，但铜主要存在于非活性残留组分中。此外，沉积物质量准则和风险评估代码的评估表明，所有采样点的铜污染风险较低。然而，沉积物-水界面的DGT测量结果显示，除了梅溪河上游和长江干流外，大多数采样点的铜从沉积物向覆水有流出。有趣的是，三条支流的扩散通量从上游到下游呈增加趋势。DIFS模型模拟进一步表明，最高的再供应能力和解吸率出现在朱衣河和梅溪河上游。事实上，朱衣河从上游到下游铜的积累显著提高了铜的再供应能力。因此，应更加关注三峡水库中的铜迁移，特别是在朱衣河和梅溪河上游。
