摘要
The Ordos Cretaceous Groundwater Basin, located in an arid-semiarid area in northwestern China, is a large-style groundwater basin. SO4^2- is one of the major harmful components in groundwater. Dissolved SO4^2- concentrations, and δ^34S-SO4^2- and δ^18O-SO4^2- in groundwater from 14 boreholes and in gypsum from aquifer were analyzed. Results show that SO4^2- in shallow groundwaters originates from precipitation, sulfide oxidation, and dissolution of stratum sulphate, with a big range of δ^34S values, from -10.7‰ to 9.2‰, and addition of SO4^2- in deep groundwater results from dissolution of stratum sulphate, with bigger δ^34S values, from 7.8‰ to 18.5‰, compared with those in shallow groundwater. This research also indicates that three types of sulphate are present in the strata, and characterized by high δ^34S values and high δ^18O values-style, high δ^34S values and middle δ^18O valuesstyle, middle δ^34S values and low δ^18O values-style, respectively. The δ^34S-SO4^2- and δ^18O-SO4^2- in groundwater have a good perspective for application in distinguishing different groundwater systems and determining groundwater circulation and evolution in this area.
The Ordos Cretaceous Groundwater Basin, located in an arid-semiarid area in northwestern China, is a large-style groundwater basin. SO4^2- is one of the major harmful components in groundwater. Dissolved SO4^2- concentrations, and δ^34S-SO4^2- and δ^18O-SO4^2- in groundwater from 14 boreholes and in gypsum from aquifer were analyzed. Results show that SO4^2- in shallow groundwaters originates from precipitation, sulfide oxidation, and dissolution of stratum sulphate, with a big range of δ^34S values, from -10.7‰ to 9.2‰, and addition of SO4^2- in deep groundwater results from dissolution of stratum sulphate, with bigger δ^34S values, from 7.8‰ to 18.5‰, compared with those in shallow groundwater. This research also indicates that three types of sulphate are present in the strata, and characterized by high δ^34S values and high δ^18O values-style, high δ^34S values and middle δ^18O valuesstyle, middle δ^34S values and low δ^18O values-style, respectively. The δ^34S-SO4^2- and δ^18O-SO4^2- in groundwater have a good perspective for application in distinguishing different groundwater systems and determining groundwater circulation and evolution in this area.
基金
supported by the China Geological Survey(grant No.1212010331302)
National Science and Technology Project(grant No. 2006BAB01A10)
International Atomic Energy Agency(grant No.CPR8012,CPR8017)
