Characteristics of groundwater cycle using deuterium, oxygen-18 and hydrochemistry in Chaobai River Basin
基于氢氧同位素与水化学的 潮白河流域地下水水循环特征

In order to study the formation and evolution law of groundwater quality in the Chaobai River Basin in the changing environment, groundwater in different layers was investigated and sampled to analyze their environmental isotope (hydrogen and oxygen-18) and hydrochemistry composition. The recharge source of groundwater and the relationship between aquifers can be identified by these results.The compositions of environmental isotope δD and δ18O of rainfall and of groundwater show that evaporation occurred to different degrees with rainfall recharging to the groundwater.The shorter the distance is to the Bohai Sea, the greater the groundwater affected by evaporation. The groundwater in plain was synthetically affected by different water sources.Rainfall was the main source of groundwater in piedmont, which was affected by evaporation strongly.Results of hydrochemical analysis showed that water quality in mountain groundwater was composed of Ca2+ and HCO-3, named as Ca2+-Mg2+-HCO-3 type. The piedmont groundwater belonged to Ca2+-Mg2+-HCO-3,Na+-K+-HCO-3,Mg2+-Ca2+-HCO-3 and Ca2+-Mg2+-Cl--SO2-4 type, groundwater in plain to Mg2+, Na+ and HCO-3 type, and groundwater in alluvium-marine sediment plain near the Bohai Sea to Ca2+-Mg2+-HCO-3 type and Ca2+-Mg2+-Cl--SO2-4type. The hydrochemistry verified the leakage recharge was assured. The anions were high in mountainous region, low in piedmont and plain, and rose near the Bohai Sea. The groundwater type along the flow direction of the Chaobai River Basin was Ca2+-Mg2+-HCO-3 Na+-K+-HCO-3 Ca2+-Mg2+-HCO-3. Based on these results, a concept model of groundwater formation and water quality evolution in the Chabai River Basin was set up. The research provided scientific basis for reasonably developing groundwater in this region.