The Turpan Basin is located in the arid zone of northwestern China and is a typical closed inland basin surrounded by high mountains. It is one of the most arid regions in the world and, as a result, the groundwater i...The Turpan Basin is located in the arid zone of northwestern China and is a typical closed inland basin surrounded by high mountains. It is one of the most arid regions in the world and, as a result, the groundwater in this area is very important for both domestic and agricultural uses. In the present study, the relationships of major elements（K＋, Na＋, Ca2＋, Mg2＋, HCO3-, SO42- and Cl-） and environmental isotopes（δ18O, δ2H and T） in groundwater were analyzed to investigate the evolution of the regional hydrochemistry within the Turpan Basin. The hydrochemistry results demonstrate that groundwater with high total dissolved solids（TDS） concentration is dominated by sodium chloride（Na-Cl） and sodium sulfate（Na-SO4） type water, whereas that with low TDS concentration（typically from near mountain areas） is dominated by calcium bicarbonate（Ca-HCO3） type water. The evolution of groundwater hydrochemistry within the Turpan Basin is a result of calcium carbonate precipitation, evaporation concentration, cation exchange and dissolution of evaporites（i.e. halite, mirabilite and gypsum）. Furthermore, evaporite dissolution associated with irrigation practice plays a key role in the groundwater salinization, especially in the central part of the basin. Environmental isotopes reveal that the groundwater is recharged by precipitation in the mountain areas and fast vertical infiltration of irrigation return flow. In the southern sub-basin the shallow groundwater and the deep groundwater is separated at a depth of about 40 m, with substantial differences in terms of hydrochemical and isotopic characteristics. The results are useful for decision making related to sustainable water resource utilization in the Turpan Basin and other regions in northwestern China.展开更多
The formation mechanism of high salinity geothermal water is significant for utilizing geothermal resources and mineral resources.The high salinity in geothermal water may be derived from the geothermal mother fluid o...The formation mechanism of high salinity geothermal water is significant for utilizing geothermal resources and mineral resources.The high salinity in geothermal water may be derived from the geothermal mother fluid or from the evaporite dissolution.It is difficult to distinguish between these two sources because they may have similar hydrochemistry.In this paper,water chemistry and stable isotopes were used to explore the high salinity geothermal water in Yanchanghe geothermal field,central China.It is a lowtemperature hydrothermal system in the inland karst area.The thermal water is Cl-Na type with high salinity(TDS>8,400 mg/L).The modified silicon thermometer is more suitable and the reasonable result is about 58.8℃.The maximum circulation depth is 1.9 km.Using the temperature of hot and cold water to estimate the mixing ratio is 58%-81%.Saturation index(SI),Na/1000-K/100-Mg1/2 and Gibbs diagram suggest that the main source of salt in geothermal water is derived from the evaporite dissolution,which provides Cl-of 11,264-31,279 mg/L and Na+of 9,272-21,236 mg/L.We found the combination of temperature and hydrogeochemistry can be used to investigate the formation mechanism and mixing process of high-salinity geothermal water formed in a karst low-temperature hydrothermal system.展开更多
基金funded by Coal Base Groundwater Exploration (Eastern Xinjiang) under the Xinjiang Uygur Autonomous Region 358 Project
文摘The Turpan Basin is located in the arid zone of northwestern China and is a typical closed inland basin surrounded by high mountains. It is one of the most arid regions in the world and, as a result, the groundwater in this area is very important for both domestic and agricultural uses. In the present study, the relationships of major elements（K＋, Na＋, Ca2＋, Mg2＋, HCO3-, SO42- and Cl-） and environmental isotopes（δ18O, δ2H and T） in groundwater were analyzed to investigate the evolution of the regional hydrochemistry within the Turpan Basin. The hydrochemistry results demonstrate that groundwater with high total dissolved solids（TDS） concentration is dominated by sodium chloride（Na-Cl） and sodium sulfate（Na-SO4） type water, whereas that with low TDS concentration（typically from near mountain areas） is dominated by calcium bicarbonate（Ca-HCO3） type water. The evolution of groundwater hydrochemistry within the Turpan Basin is a result of calcium carbonate precipitation, evaporation concentration, cation exchange and dissolution of evaporites（i.e. halite, mirabilite and gypsum）. Furthermore, evaporite dissolution associated with irrigation practice plays a key role in the groundwater salinization, especially in the central part of the basin. Environmental isotopes reveal that the groundwater is recharged by precipitation in the mountain areas and fast vertical infiltration of irrigation return flow. In the southern sub-basin the shallow groundwater and the deep groundwater is separated at a depth of about 40 m, with substantial differences in terms of hydrochemical and isotopic characteristics. The results are useful for decision making related to sustainable water resource utilization in the Turpan Basin and other regions in northwestern China.
基金supported by the National Natural Science Foundation of China(Grant number:41440027)。
文摘The formation mechanism of high salinity geothermal water is significant for utilizing geothermal resources and mineral resources.The high salinity in geothermal water may be derived from the geothermal mother fluid or from the evaporite dissolution.It is difficult to distinguish between these two sources because they may have similar hydrochemistry.In this paper,water chemistry and stable isotopes were used to explore the high salinity geothermal water in Yanchanghe geothermal field,central China.It is a lowtemperature hydrothermal system in the inland karst area.The thermal water is Cl-Na type with high salinity(TDS>8,400 mg/L).The modified silicon thermometer is more suitable and the reasonable result is about 58.8℃.The maximum circulation depth is 1.9 km.Using the temperature of hot and cold water to estimate the mixing ratio is 58%-81%.Saturation index(SI),Na/1000-K/100-Mg1/2 and Gibbs diagram suggest that the main source of salt in geothermal water is derived from the evaporite dissolution,which provides Cl-of 11,264-31,279 mg/L and Na+of 9,272-21,236 mg/L.We found the combination of temperature and hydrogeochemistry can be used to investigate the formation mechanism and mixing process of high-salinity geothermal water formed in a karst low-temperature hydrothermal system.
