Groundwater geochemistry in the Changping area,Beijing

Based on stable isotopes and chemical compositions of groundwater samples collected in the Changping District of Beijing,the characteristics of groundwater recharge are analyzed.Through the discussion of groups of the samples,it is recognized that the third group of the samples are characterized by the vertical movement to the groundwater from the infiltration of precipitation;the first group of the samples are characterized by the recharge from the underlying Carbonate aquifer bedrock to the overlying Quaternary aquifer.The second group of the samples shows the local vertical infiltration.Three samples in the 4 samples of the fourth group indicate recharge from precipitation and the other one from a mixture of recharge.The results indicate that distribution of groundwater in the Quaternary aquifer in Changping and its recharge vary greatly,showing the complexity of the groundwater distribution in the slope plain of a mountain front in a semiarid area.