A Hydrogen and Oxygen Isotope Study of Groundwater in the Yongding River Drainage of Beijing and Its Environmental Significance
北京永定河流域地下水氢氧同位素研究及环境意义

On the basis of isotopic geochemistry, the authors studied the status and the supply characteristics of groundwater in the Yongding River drainage of Beijing. Some samples of groundwater were systematically collected from different areas and different depths and then analyzed for their contents of deuterium, oxygen and tritium. Based on a study of the analytical results, the authors have reached the conclusion that the groundwater in the superficial aquifer is mainly made up of young groundwater. In the past ten years, groundwater has been supplied by vertically filtering atmospheric precipitation, and groundwater from the middle to the deep aquifer is generally combined with the upper groundwater, and the proportion of the young groundwater is steadily increasing. In addition, there exists the mixture of some young groundwater in some places, though the groundwater in the deep aquifer remains mainly made up of groundwater older than 50 years. The groundwater condition in this area suggests that there exists the phenomenon that the superficial groundwater has penetrated into the deep aquifer. This could result in the deterioration of the quality of the groundwater in the deep aquifer. It can thus be concluded that the status of the groundwater resource in this area is not satisfactory due to the human unreasonable exploitation.