Characteristics of soil lithology and pollutants in typical contamination sites in China

There are massive contaminated sites with distinct distribution pattern and regional characteristics need to be remediated in China. In order to develop suitable remediation techniques, it is necessary to understand the complexity of the aquifer system, the heterogeneity of the media and the complexity of the contaminants at each site. In this paper, we summarized the data of 136 organic contamination sites in China, focusing on the characteristics of site distribution, soil layers and contaminants. At present, the remediation projects for organic contamination sites are mainly concentrated in the Beijing-Tianjin-Hebei and Shanghai-Nanjing-Hangzhou areas. Heterogeneous soil layers are found in all organic contamination sites and they contain low-permeable media such as clay. Sixty-seven percent of the soil layers and sites show high heterogeneity. The soil permeability in the Shanghai-Nanjing-Hangzhou area is generally lower compared to the Beijing-Tianjin-Hebei area. In addition, the survey depth (20.3 m) of the contaminated sites in Beijing-Tianjin-Hebei and the central and southern Liaoning areas is generally deeper compared to the Shanghai-Nanjing-Hangzhou area (12.8 m). The most common organic contaminants in the groundwater are chlorinated organic compounds, including chloroalkanes (in 84% of sites), chlorinated benzenes (in 46% of sites) and chloroalkenes (in 33% of sites). Among chlorinated solvents, dichloroethane, monochlorobenzene and trichloromethane are the three most common pollutants. © 2021, Editorial Office of Earth Science Frontiers. All right reserved.