Abstract

Groundwater quality evolution was investigated in an urban area of Beijing with multilayered geological formations. The majority of the samples collected during this investigation were found to contain high concentrations of nitrate, which is a serious water quality issue. In addition, this study attempted to explain the controlling processes responsible for the various facies. Overall, the distribution of soluble ions in the groundwater was stratified in the research area because of clay layers. Furthermore, the clay was found to control the concentration of cations and silica, as well as that of chloride ions in the groundwater. Taken together, these findings indicate that the clay layer is one of the most important factors involved in control of groundwater quality in the research area.

Key words: Groundwater, nitrate, clay, silica, cations, chloride.