Rock thermal physical properties play a crucial role in understanding deep thermal conditions,modeling the thermal structure of the lithosphere,and discovering the evolutionary history of sedimentary basins.Recent adv...Rock thermal physical properties play a crucial role in understanding deep thermal conditions,modeling the thermal structure of the lithosphere,and discovering the evolutionary history of sedimentary basins.Recent advancements in geothermal exploration,particularly the identification of high-temperature geothermal resources in Datong Basin,Shanxi,China,have opened new possibilities.This study aims to characterize the thermal properties of rocks and explore factors influencing thermal conductivity in basins hosting high-temperature geothermal resources.A total of 70 groups of rock samples were collected from outcrops in and around Datong Basin,Shanxi Province.Thermal property tests were carried out to analyze the rock properties,and the influencing factors of thermal conductivity were studied through experiments at different temperature and water-filled states.The results indicate that the thermal conductivity of rocks in Datong,Shanxi Province,typically ranges from 0.690 W/(m·K)to 6.460 W/(m·K),the thermal diffusion coefficient ranges from 0.441 mm^(2)/s to 2.023 mm^(2)/s,and the specific heat capacity of the rocks ranges from 0.569 KJ/(kg·℃)to 1.117 KJ/(kg·°C).Experimental results reveal the impact of temperature and water saturation on the thermal conductivity of the rock.The thermal conductivity decreases with increasing temperature and rises with high water saturation.A temperature correction formula for the thermal conductivity of different lithologies in the area is proposed through linear fitting.The findings from this study provide essential parameters for the assessment and prediction,development,and utilization of geothermal resources in the region and other basins with typical high-temperature geothermal resource.展开更多
[Objective] Saline-alkali wasteland is a kind of land use type that formed by soil salinization and secondary salinization. To study the causes of spatial distri- bution of saline-alkali wasteland could be used as ref...[Objective] Saline-alkali wasteland is a kind of land use type that formed by soil salinization and secondary salinization. To study the causes of spatial distri- bution of saline-alkali wasteland could be used as reference for the amelioration and is significant for developing the reserved land with great potential. [Method] The re- search set a total of 1 729 sampling points in the study area of 34 433 hm2. Spa- tial analyses were used to find out the causes of saline-alkali wasteland in Datong basin from four factors： topography, geology, hydrology and soil. DEM and land use data were used to calculate distribution index of topography, and distribution of the total salinity （TS） and pH was analyzed by means of IDW interpolation. [Result] The results showed that saline-alkali wasteland was distributed on flat and low-lying ter- rains with poor drainage, which led to salt accumulation. 87% of saline-alkali wasteland was distributed on Quaternary Holocene alluvium whose performance of soil hydraulic conductivity was poor. TS value distribution was that in midstream re- gion was the highest, less in upstream region and the least in downstream region along the rivers, and TS value decreased when distance between saline-alkali wasteland and rivers increased. The major soil types in Datong basin were fluvo- aquic soil and saline soil. Both of the two soil types were of high TS value and pH value, and heavily salinized and strongly alkalized. [Conclusion] High groundwater table and the existence of two salt accumulation centers are the two causes of saline-alkali wasteland in Datong basin. The key to ameliorate saline-alkali waste- land is to descend the groundwater table and lessen salt accumulation.展开更多
Hydrogeochemical investigations were carried out in the Datong Basin, northern China to understand the sources and mechanisms of fluoride enrichment in the groundwater. The re- sults indicate that fluoride concentrat...Hydrogeochemical investigations were carried out in the Datong Basin, northern China to understand the sources and mechanisms of fluoride enrichment in the groundwater. The re- sults indicate that fluoride concentrations reached up to 7.2 mg/L, and the hydrochemical type changed from Ca-HCO3, Ca-Mg-HCO3 water in the recharge areas to Na-HCO3, Na-Mg-HCO3 in the flow-through area and ultimately to Na-CI-HCO3, Na-SO4-CI and Na-CI in the discharge areas. The to- tal fluorine contents in the soils ranged between 277.6 and 1 292.5 mg/kg, which can provide large amounts of fluorine from fluorine-bearing minerals, such as fluorite, biotite and amphibole. The con- centration of water-soluble fluorine ranged from 3.9 to 49.9 mg/kg （mostly less than 1% of the total fluorine） in the soils and rocks that, may have released sufficient fluorine into the groundwater. The results of PHREEQC simulations indicate that most of the analyzed samples are under-saturated with respect to fluorite （CaFz） from the recharge area to the discharge area. The fluctuation of F concentra- tion in the 11 months indicates that the seasonal variation and the agricultural activity also affect the fluoride content in the groundwater. Fluoride enrichment in groundwater is predominantly controlled by fluorite solubility, residence time, evapotranspiration intensity and seasonal variation in this arid and semi-arid area.展开更多
Although arsenic-contaminated groundwater in the Datong Basin has been studied for more than 10 years, little has been known about the complex patterns of solute transport in the aquifer systems. Field monitoring and ...Although arsenic-contaminated groundwater in the Datong Basin has been studied for more than 10 years, little has been known about the complex patterns of solute transport in the aquifer systems. Field monitoring and transient 3D unsaturated groundwater flow modeling studies were car- ried out on the riparian zone of the Sanggan River at the Datong Basin, northern China, to better un- derstand the effects of groundwater flow on As mobilization and transport. The results indicate that ir- rigation is the primary factor in determining the groundwater flow paths. Irrigation can not only in- crease groundwater level and reduce horizontal groundwater velocity and thereby accelerate vertical and horizontal groundwater exchange among sand, silt and clay formations, but also change the HS concentration, redox conditions of the shallow groundwater. Results of net groundwater flux estimation suggest that vertical infiltration is likely the primary control of As transport in the vadose zone, while horizontal water exchange is dominant in controlling As migration within the sand aquifers. Recharge water, including irrigation return water and flushed saltwater, travels downward from the ground surface to the aquifer and then nearly horizontally across the sand aquifer. The maximum value of As enriched in the riparian zone is roughly estimated to be 1 706.2 mg.d-1 for a horizontal water exchange of 8.98 m3.d-1 close to the river and an As concentration of 190 μg.L-1.展开更多
超采区的地下水变化趋势分析对于区域水资源可持续管理具有重要意义。本文以大同盆地浅层地下水超采区为研究对象,分析了含水层结构和地下水的补给、径流、排泄条件,明确了潜水含水层为影响地下水变化的主要区域。基于GMS与MODFLOW软件...超采区的地下水变化趋势分析对于区域水资源可持续管理具有重要意义。本文以大同盆地浅层地下水超采区为研究对象,分析了含水层结构和地下水的补给、径流、排泄条件,明确了潜水含水层为影响地下水变化的主要区域。基于GMS与MODFLOW软件,建立了大同盆地潜水含水层各向同性非均质二维非稳定流模型,利用实测地下水流场对模型进行了验证,开展了未来不同场景条件下地下水位预测模拟与分析。结果表明,大同盆地2010—2019年平均地下水开采量(6.0861亿m^(3))大于2001—2016年平均地下水补给量(5.6254亿m^(3)),地下水位下降趋势明显。若地下水开采量下降至2019年开采量的85%,至2035年平均地下水位可回升11.6 m,恢复速度约0.68 m a;若综合考虑未来水源替换工程,至2035年地下水位可显著回升,恢复速率可达1.4 m a。本文研究成果可为大同盆地地下水管控提供科学依据,同时对于我国北方类似地下水超采区的水资源管理和评价具有一定参考价值。展开更多
From the near-field records of aftershock of Datong earthquakes in October 1989 and March 1991,an extra phase between P and S arrivals is found. High-precision epicenter location shows that some of these records are o...From the near-field records of aftershock of Datong earthquakes in October 1989 and March 1991,an extra phase between P and S arrivals is found. High-precision epicenter location shows that some of these records are obtained with the incidental angle less than the critical angle. This excludes the possibility that the extra wave phase is a refractive wave from ground surface. Particle motion analysis shows that the characteristic of the extra wave is similar to that of wave, so it is possible that the extra phase is an S to P convert wave from the bottom of sediment basin. Suppose a low velocity layer covers a high velocity basement. Successful simulation by the synthetic seismogram confirms that the extra phase is an S-P convert wave from the interface of the basin bottom. Modifying the depth of interface at each ray path to match the waveform, we obtain an interface distribution in space. In this way, a brief bottom image could be shown, and the Datong basin has a 'V' shaped bottom.展开更多
基金supported by the Geothermal Survey Project of the China Geological Survey(Grant No.DD20221676)the Shanxi Geoscience Think Tank Development Fund 2023–001 and Basic Research Operations Project of the Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences(SK202212).
文摘Rock thermal physical properties play a crucial role in understanding deep thermal conditions,modeling the thermal structure of the lithosphere,and discovering the evolutionary history of sedimentary basins.Recent advancements in geothermal exploration,particularly the identification of high-temperature geothermal resources in Datong Basin,Shanxi,China,have opened new possibilities.This study aims to characterize the thermal properties of rocks and explore factors influencing thermal conductivity in basins hosting high-temperature geothermal resources.A total of 70 groups of rock samples were collected from outcrops in and around Datong Basin,Shanxi Province.Thermal property tests were carried out to analyze the rock properties,and the influencing factors of thermal conductivity were studied through experiments at different temperature and water-filled states.The results indicate that the thermal conductivity of rocks in Datong,Shanxi Province,typically ranges from 0.690 W/(m·K)to 6.460 W/(m·K),the thermal diffusion coefficient ranges from 0.441 mm^(2)/s to 2.023 mm^(2)/s,and the specific heat capacity of the rocks ranges from 0.569 KJ/(kg·℃)to 1.117 KJ/(kg·°C).Experimental results reveal the impact of temperature and water saturation on the thermal conductivity of the rock.The thermal conductivity decreases with increasing temperature and rises with high water saturation.A temperature correction formula for the thermal conductivity of different lithologies in the area is proposed through linear fitting.The findings from this study provide essential parameters for the assessment and prediction,development,and utilization of geothermal resources in the region and other basins with typical high-temperature geothermal resource.
文摘[Objective] Saline-alkali wasteland is a kind of land use type that formed by soil salinization and secondary salinization. To study the causes of spatial distri- bution of saline-alkali wasteland could be used as reference for the amelioration and is significant for developing the reserved land with great potential. [Method] The re- search set a total of 1 729 sampling points in the study area of 34 433 hm2. Spa- tial analyses were used to find out the causes of saline-alkali wasteland in Datong basin from four factors： topography, geology, hydrology and soil. DEM and land use data were used to calculate distribution index of topography, and distribution of the total salinity （TS） and pH was analyzed by means of IDW interpolation. [Result] The results showed that saline-alkali wasteland was distributed on flat and low-lying ter- rains with poor drainage, which led to salt accumulation. 87% of saline-alkali wasteland was distributed on Quaternary Holocene alluvium whose performance of soil hydraulic conductivity was poor. TS value distribution was that in midstream re- gion was the highest, less in upstream region and the least in downstream region along the rivers, and TS value decreased when distance between saline-alkali wasteland and rivers increased. The major soil types in Datong basin were fluvo- aquic soil and saline soil. Both of the two soil types were of high TS value and pH value, and heavily salinized and strongly alkalized. [Conclusion] High groundwater table and the existence of two salt accumulation centers are the two causes of saline-alkali wasteland in Datong basin. The key to ameliorate saline-alkali waste- land is to descend the groundwater table and lessen salt accumulation.
基金supported by the National Natural Science Foundation of China(No.41120124003)the Ministry of Education of China
文摘Hydrogeochemical investigations were carried out in the Datong Basin, northern China to understand the sources and mechanisms of fluoride enrichment in the groundwater. The re- sults indicate that fluoride concentrations reached up to 7.2 mg/L, and the hydrochemical type changed from Ca-HCO3, Ca-Mg-HCO3 water in the recharge areas to Na-HCO3, Na-Mg-HCO3 in the flow-through area and ultimately to Na-CI-HCO3, Na-SO4-CI and Na-CI in the discharge areas. The to- tal fluorine contents in the soils ranged between 277.6 and 1 292.5 mg/kg, which can provide large amounts of fluorine from fluorine-bearing minerals, such as fluorite, biotite and amphibole. The con- centration of water-soluble fluorine ranged from 3.9 to 49.9 mg/kg （mostly less than 1% of the total fluorine） in the soils and rocks that, may have released sufficient fluorine into the groundwater. The results of PHREEQC simulations indicate that most of the analyzed samples are under-saturated with respect to fluorite （CaFz） from the recharge area to the discharge area. The fluctuation of F concentra- tion in the 11 months indicates that the seasonal variation and the agricultural activity also affect the fluoride content in the groundwater. Fluoride enrichment in groundwater is predominantly controlled by fluorite solubility, residence time, evapotranspiration intensity and seasonal variation in this arid and semi-arid area.
基金financially supported by the National Natural Science Foundation of China (Nos. 40830748, 40902071 and 41120124003)the Ministry of Science and Technology of China (No. 2012AA062602)the Ministry of Education of China (111 project and Priority Development Projects of SRFDP)
文摘Although arsenic-contaminated groundwater in the Datong Basin has been studied for more than 10 years, little has been known about the complex patterns of solute transport in the aquifer systems. Field monitoring and transient 3D unsaturated groundwater flow modeling studies were car- ried out on the riparian zone of the Sanggan River at the Datong Basin, northern China, to better un- derstand the effects of groundwater flow on As mobilization and transport. The results indicate that ir- rigation is the primary factor in determining the groundwater flow paths. Irrigation can not only in- crease groundwater level and reduce horizontal groundwater velocity and thereby accelerate vertical and horizontal groundwater exchange among sand, silt and clay formations, but also change the HS concentration, redox conditions of the shallow groundwater. Results of net groundwater flux estimation suggest that vertical infiltration is likely the primary control of As transport in the vadose zone, while horizontal water exchange is dominant in controlling As migration within the sand aquifers. Recharge water, including irrigation return water and flushed saltwater, travels downward from the ground surface to the aquifer and then nearly horizontally across the sand aquifer. The maximum value of As enriched in the riparian zone is roughly estimated to be 1 706.2 mg.d-1 for a horizontal water exchange of 8.98 m3.d-1 close to the river and an As concentration of 190 μg.L-1.
文摘超采区的地下水变化趋势分析对于区域水资源可持续管理具有重要意义。本文以大同盆地浅层地下水超采区为研究对象,分析了含水层结构和地下水的补给、径流、排泄条件,明确了潜水含水层为影响地下水变化的主要区域。基于GMS与MODFLOW软件,建立了大同盆地潜水含水层各向同性非均质二维非稳定流模型,利用实测地下水流场对模型进行了验证,开展了未来不同场景条件下地下水位预测模拟与分析。结果表明,大同盆地2010—2019年平均地下水开采量(6.0861亿m^(3))大于2001—2016年平均地下水补给量(5.6254亿m^(3)),地下水位下降趋势明显。若地下水开采量下降至2019年开采量的85%,至2035年平均地下水位可回升11.6 m,恢复速度约0.68 m a;若综合考虑未来水源替换工程,至2035年地下水位可显著回升,恢复速率可达1.4 m a。本文研究成果可为大同盆地地下水管控提供科学依据,同时对于我国北方类似地下水超采区的水资源管理和评价具有一定参考价值。
基金State Key Basic Research Development and Programming Project (95-13-05-02) the Federal Institute for Geosciences and Natural Resources, Germany.
文摘From the near-field records of aftershock of Datong earthquakes in October 1989 and March 1991,an extra phase between P and S arrivals is found. High-precision epicenter location shows that some of these records are obtained with the incidental angle less than the critical angle. This excludes the possibility that the extra wave phase is a refractive wave from ground surface. Particle motion analysis shows that the characteristic of the extra wave is similar to that of wave, so it is possible that the extra phase is an S to P convert wave from the bottom of sediment basin. Suppose a low velocity layer covers a high velocity basement. Successful simulation by the synthetic seismogram confirms that the extra phase is an S-P convert wave from the interface of the basin bottom. Modifying the depth of interface at each ray path to match the waveform, we obtain an interface distribution in space. In this way, a brief bottom image could be shown, and the Datong basin has a 'V' shaped bottom.
