Hydrogeochemical characteristic and recognization of saline groundwater formation and evolution in silty coast of the Yellow Sea and Bohai Sea, Eastern China

Saline groundwater is a valuable unconventional water resource in silty coastal zone, which contain complex and fragile sedimentary hydrological environments that are widely distributed vulnerable to human activities. Coastal salinization along the eastern coast of China since late Pleistocene thought be response global environmental change. Previous studies have shown spatial temporal link between development saline deposition marine strata. However, becoming an increasing problem hydrogeochemical characteristics cause or desalinization remain poorly understood. In this study, we compared relationships environment two representative, muddy zone Yellow Sea (YSC) Bohai (BSC). Our monitoring results show varies from fresh water, brackish saltwater, brine moving offshore BSC, with total dissolved solid (TDS) concentrations 203–184,196 mg/L. contrast, absent YSC, where TDS range 280 41,690 The δ 2 H 18 O values indicate freshwater–seawater–brine freshwater–seawater mixing main processes leading enrichment BSC respectively. Based on relationship major cations, Cl − , Cl/Br ratios, salinity primarily due saltwater intrusion secondly water–rock interactions (i.e., evaporitic salt dissolution cation exchange). regression curves plots Na–Cl (Ca+Mg)–(CO 3 +SO 4 ) negative slopes (−0.33 −0.34, respectively) for samples indicating Na exchange Ca seawater residual intrusion. (or brine) reverse ion has invaded aquifer, + replacing 2+ Mg . These enhance our understanding formation evolution groundwater, provide insights into groundwaters other zones.