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 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.
Sci Total Environ. 2018 Jul 1;628-629:241-248. doi: 10.1016/j.scitotenv.2018.01.322. Epub 2018 Feb 13.
The mobility and transfer of trace metals in sediments are vital to understanding trace metals environmental behavior in water environment. However, as a predominant aquatic carcinogen, an effective method for assessing the release and deposition for Cr at the sediment-water interface (SWI) is still not clearly understood. Here we established a comprehensive methodology to evaluate the release risk of Cr at the SWI combining regional geochemical baseline (RGB) and diffusive gradients in thin films (DGT). Sediment cores and water samples were collected in the two tributaries and mainstream of the Three Gorges Reservoir, which is the world's largest man-made hydroelectric station. Results showed that the calculated Cr carcinogenic risks in surface water did not exceed US EPA maximum recommended level. The RGB of Cr (85.53 ± 14.44 mg/kg) were calculated and the differentials between Cr concentration and RGB in surface sediments showed the average anthropogenic contribution rate was 6.03% and the upstream of Meixi River (MX-S) and mainstream were influenced by anthropogenic activities. The net diffusive flux using DGT showed that Cr in the midstream of Caotang River and MX had the potential to move upwards into the overlying water. Furthermore, combining the results of differential (Cr concentration vs. RGB) and the net flux, MX-S was the only site with a risk of Cr release. To the best of our knowledge, this study is the first attempt to combine RGB and DGT to scientifically assess metal release at SWI and provided a new perspective to comprehensively assess metal pollution in water environment.
痕量金属在沉积物中的迁移和转化对于了解水环境中痕量金属的环境行为至关重要。然而，作为主要的水生致癌物，对于评估 Cr 在沉积物-水界面（SWI）的释放和沉积仍然没有明确的理解。在这里，我们建立了一种综合的方法，结合区域地球化学基线（RGB）和薄膜扩散梯度（DGT）来评估 SWI 中 Cr 的释放风险。在三峡水库的两个支流和主流中采集了沉积物岩芯和水样，三峡水库是世界上最大的人工水电站。结果表明，地表水中 Cr 的致癌风险计算值未超过美国环保署推荐的最高水平。计算了 Cr 的 RGB（85.53±14.44mg/kg），表层沉积物中 Cr 浓度与 RGB 的差值表明，人为活动的平均贡献率为 6.03%，梅溪河（MX-S）和主流上游受到人为活动的影响。使用 DGT 测量的净扩散通量表明，在草堂河和 MX 的中游，Cr 有向上进入上覆水的迁移潜力。此外，结合差分（Cr 浓度与 RGB 的差异）和净通量的结果，MX-S 是唯一一个有 Cr 释放风险的地点。据我们所知，这项研究首次尝试将 RGB 和 DGT 结合起来，科学地评估 SWI 中的金属释放，并为全面评估水环境中的金属污染提供了新的视角。
