Analysis Of Hydrogeochemistry And Stable Isotopes Of Surface Water And Groundwater In North China Plain

The North China Plain is China’s severe water shortage area，in recent years，human beings over-rely on groundwater resources，causing a variety of environmentalissues in the processes of developing groundwater，such as the continual decline ofgroundwater level、the expansion of groundwater depression cone，sea and salt waterintrusion and so on，these seriously affect the groundwater circulation conditions，therefore，recognizing the present cycle of groundwater conditions is important toensure the rational development and sustainable use of groundwater resources．This paper selected Shijiazhuang-Bohai Bay hydrogeological profile as the studyarea，on the basis of the regional natural geographical、hydrological and geologicalconditions，combining with the hydrogeochemical and stable isotope methods，usingmultidisciplinary perspective to study the recharge mode of the groundwater，thedifferences of recharging environment and the relationship between shallowgroundwater and surface water in the North China Plain，it provided a scientific basisfor the rational development and utilization of groundwater resources．The groundwater which was recharged by modern precipitation circulatedactively in piedmont plain of the study area．It was rich in δ²H and δ¹⁸O and poorin Cl^-．The temperature of¹⁸O matched the modern temperature；The groundwater incentral plain had a relatively low value ofδ²H andδ¹⁸O．The data of¹⁸O temperature，3H and¹⁴C showed that shallow phreatic water was recharged by modern precipitationfrom Holocene Age．As the result of the slower speed of recharge of precipitation andit was influenced by paleochanle，the Cl^-concentration was extremely increased；Deepconfined water was recharged by cold period precipitation of Pleistocene．The Cl^-concentration of groundwater in the wells which depth were less than300m wasreduced with the depth increasing，it was because this district formed the cone ofdepression，on the one hand，it caused overlying salt water flow to supply the deepfresh water，on the other hand，it speeded up the cycle rate of groundwater；Shallow phreatic water in littoral plain which was recharged by precipitation was rich inδ²Handδ¹⁸O which was accorded with continental effects of stable isotope．Thetemperature of¹⁸O in deep confined water and the data of¹⁴C and³⁶Cl indicated thedifference of recharge mode，the comprehensive analysis reasons was that the deepconfined groundwater was recharged by precipitation in Last glacial and was mixedby interglacial precipitation，the recharge ratio of precipitation of this district wasextremely lower，and groundwater was influenced by the sea instrusion，Cl^-concen-tration was extremely increased．The analysis of the relationship betweenδ²H andδ¹⁸O、ions/Cl and TDSshowed that huangbizhuang reservoir in the piedmont plain recharged groundwater，from the top of blunt flood product fan to the mid-blunt flood product fan，groundwater near the HuTuoHe river accepted the river supply，and no.16samplewhich was far away from the river was not accepted river recharge，its each ioncontent can be approximately represent the chemical characteristic value onlyaccepted precipitation infiltration； The river and groundwater were frequentlytransformed with eath other by the Ziya new river，of which the mixed ratio of theriver （such as no.59sample point） into groundwater was60.2%，and the groundwater（such as no.22sample point） into the river at100%；Most of surface water andgroundwater were mixed with sea water as the results of sea instrusion influencial inthe Coastal plain，which can be reflected by the Na-Cl relationship chart which thesample point closed to the seawater dilution line，the mutual transformation betweenthe surface water and groundwater was happened in the area of the south dagangdistrict．...