School of Science, China University of Geosciences, Beijing 100083, PR China.
School of Science, China University of Geosciences, Beijing 100083, PR China; Key Laboratory of Ecogeochemistry, Ministry of Natural Resources, Beijing 100037, PR China.
Sci Total Environ. 2022 Oct 20;844:156922. doi: 10.1016/j.scitotenv.2022.156922. Epub 2022 Jul 5.
Black shale is rich in potentially toxic elements (PTEs) that migrate through rock weathering or rainfall, adversely affecting human health and the environment. In this study, simulated rainfall leaching experiments were used to investigate the migration patterns and leaching kinetics of PTEs in black shale from the Lower Cambrian Hetang Formation and to analyze the water quality index (WQI) of PTEs in the leachate. A comparison between the risk of PTEs in the leachate and those in the soil was also made to determine the risk sources, risk status, and distribution characteristics of PTEs in the study area. The WQI of the indoor column experimental leachate indicated the highest As contamination. The geo-accumulation index (I) and potential ecological risk (Er) of soils in the entire region revealed that the risk of Cd was the highest. Furthermore, by mapping the distribution of I and Er in soils, the risk level in the region where black shale is located was found to be significantly higher than that in other areas. Comparing the leaching rate of PTEs with the WQI from leaching experiments, the risk associated with As in soil can be inferred to originate mainly from the leaching of black shale. Previous studies on PTEs in black shale in the study area tended to focus on Cd; however, this study found that the risk of As was not negligible. The health risk assessment also showed that the risk at the location of black shale was beyond the accepted range. Overall, this study provided a new and important evaluation law for the level of pollution by PTEs and health risks in typical black shale regions.
黑色页岩富含潜在有毒元素（PTEs），这些元素会通过岩石风化或降雨迁移，对人类健康和环境造成不利影响。本研究采用模拟降雨淋溶实验，研究了下寒武统荷塘组黑色页岩中 PTEs 的迁移模式和淋溶动力学，并对淋出液中 PTEs 的水质指数（WQI）进行了分析。还比较了淋出液和土壤中 PTEs 的风险，以确定研究区 PTEs 的风险源、风险状况和分布特征。室内柱实验淋出液的 WQI 表明 As 污染最严重。整个地区土壤的地质累积指数（I）和潜在生态风险（Er）表明 Cd 的风险最高。此外，通过绘制土壤中 I 和 Er 的分布地图，发现黑色页岩所在地区的风险水平明显高于其他地区。将 PTEs 的淋出率与淋溶实验的 WQI 进行比较，可以推断出土壤中 As 的风险主要来自黑色页岩的淋溶。先前对研究区黑色页岩中 PTEs 的研究主要集中在 Cd 上；然而，本研究发现 As 的风险不容忽视。健康风险评估还表明，黑色页岩所在地的风险超出了可接受范围。总的来说，本研究为典型黑色页岩地区 PTEs 污染水平和健康风险提供了新的重要评价规律。
