Hundreds of precipitation samples collected from meteorological stations in the Ordos Basin from January 1988 to December 2005 were used to set up a local meteoric water line and to calculate weighted average isotopic...Hundreds of precipitation samples collected from meteorological stations in the Ordos Basin from January 1988 to December 2005 were used to set up a local meteoric water line and to calculate weighted average isotopic compositions of modern precipitation. Oxygen and hydrogen isotopes, with averages of-7.8‰ and -53.0‰ for δ^18O and δD, respectively, are depleted in winter and rich in spring, and gradually decrease in summer and fall, illustrating that the seasonal effect is considerable. They also show that the isotopic difference between south portion and north portion of the Ordos Basin are not obvious, and the isotope in the middle portion is normally depleted. The isotope compositions of 32 samples collected from shallow groundwater （less than a depth of 150 m） in desert plateau range from -10.6‰ to -6.0‰ with an average of-8.4‰ for δ^18O and from -85‰ to -46‰ with an average of-63‰ for δD. Most of them are identical with modern precipitation. The isotope compositions of 22 middle and deep groundwaters （greater than a depth of 275 m） fall in ranges from -11.6‰ to -8.8‰ with an average of -10.2‰ for δ^18O and from -89‰ to -63‰ with an average of -76‰ for δD. The average values are significantly less than those of modern precipitation, illustrating that the middle and deep groundwaters were recharged at comparatively lower air temperatures. Primary analysis of ^14C shows that the recharge of the middle and deep groundwaters started at late Pleistocene. The isotopes of 13 lake water samples collected from eight lakes define a local evaporation trend, with a relatively flat slope of 3.77, and show that the lake waters were mainly fed by modern precipitation and shallow groundwater.展开更多
The Ordos Basin is a large-scale sedimentary basin in northwestern China. The hydrostratigraphic units from bottom to top are pre-Cambrian metamorphic rocks, Lower Paleozoic carbonate rocks, Upper Paleozoic to Mesozoi...The Ordos Basin is a large-scale sedimentary basin in northwestern China. The hydrostratigraphic units from bottom to top are pre-Cambrian metamorphic rocks, Lower Paleozoic carbonate rocks, Upper Paleozoic to Mesozoic clastic rocks and Cenozoic deposits. The total thickness is up to 6000 m. Three groundwater systems are present in the Ordos Basin, based on the geological settings, i.e. the karst groundwater system, the Cretaceous clastic groundwater system and the Quaternary groundwater system. This paper describes systematically the groundwater flow patterns of each system and overall assessment of groundwater resources.展开更多
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- concen...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.展开更多
基金supported by the China Geological Survey and International Atomic Energy Agency.
文摘Hundreds of precipitation samples collected from meteorological stations in the Ordos Basin from January 1988 to December 2005 were used to set up a local meteoric water line and to calculate weighted average isotopic compositions of modern precipitation. Oxygen and hydrogen isotopes, with averages of-7.8‰ and -53.0‰ for δ^18O and δD, respectively, are depleted in winter and rich in spring, and gradually decrease in summer and fall, illustrating that the seasonal effect is considerable. They also show that the isotopic difference between south portion and north portion of the Ordos Basin are not obvious, and the isotope in the middle portion is normally depleted. The isotope compositions of 32 samples collected from shallow groundwater （less than a depth of 150 m） in desert plateau range from -10.6‰ to -6.0‰ with an average of-8.4‰ for δ^18O and from -85‰ to -46‰ with an average of-63‰ for δD. Most of them are identical with modern precipitation. The isotope compositions of 22 middle and deep groundwaters （greater than a depth of 275 m） fall in ranges from -11.6‰ to -8.8‰ with an average of -10.2‰ for δ^18O and from -89‰ to -63‰ with an average of -76‰ for δD. The average values are significantly less than those of modern precipitation, illustrating that the middle and deep groundwaters were recharged at comparatively lower air temperatures. Primary analysis of ^14C shows that the recharge of the middle and deep groundwaters started at late Pleistocene. The isotopes of 13 lake water samples collected from eight lakes define a local evaporation trend, with a relatively flat slope of 3.77, and show that the lake waters were mainly fed by modern precipitation and shallow groundwater.
文摘The Ordos Basin is a large-scale sedimentary basin in northwestern China. The hydrostratigraphic units from bottom to top are pre-Cambrian metamorphic rocks, Lower Paleozoic carbonate rocks, Upper Paleozoic to Mesozoic clastic rocks and Cenozoic deposits. The total thickness is up to 6000 m. Three groundwater systems are present in the Ordos Basin, based on the geological settings, i.e. the karst groundwater system, the Cretaceous clastic groundwater system and the Quaternary groundwater system. This paper describes systematically the groundwater flow patterns of each system and overall assessment of groundwater resources.
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)
文摘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.
