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In order to gain insight into the hydrochemical characteristics and formation mechanism of high fluoride groundwater in Zhuanlongwan Coal Mine, we conducted a comprehensive analysis of 48 samples including quaternary groundwater (QGW), sandstone groundwater (SGW), and mine water (MGW) using statistical analysis and hydrochemical methods. The findings demonstrate that the groundwater in Zhuanlongwan Coal Mine generally exhibits weak alkalinity, with predominant cations comprising of Ca2+ and Na+, and anions consisting of HCO3– and Cl–. The mean mass concentration of SO4 2–, Cl–, TDS, pH, and CO3 2– in groundwater follows the order of MGW>SGW>QGW, whereas HCO3– and F– exhibit the trend of SGW>MGW>QGW. Specifically, the average mass concentration of F– in QGW, SGW, and MGW is 0.76 mg/L, 4.55 mg/L, and 4.35 mg/L, respectively. Notably, most samples from SGW and MGW significantly exceed the permissible F−concentration threshold of 1.0 mg/L. The hydrochemical type of low fluoride (\begin{document}$\rho_{{\mathrm{F}}^{-}} $\end{document}1 mg/L) are mainly HCO3−Na (35.42%) and SO4·Cl−Na (45.83%). The dissolution of fluorinated minerals serves as the main source of F– in the high fluoride groundwater of Zhuanlongwan Coal Mine. Moreover, cation exchange, competitive adsorption, as well as the dissolution and precipitation of dolomite and calcite, are significant factors influencing the occurrence of high fluoride groundwater.

In recent years, mine water inrush accidents occurred several times in North China type coalfield during the mining process of the upper group of coal, and possessed great threat. Taking Dongtan Coal Mine as an example, statistical analysis, Piper trilinear diagram, Gibbs diagram, Chlorine-alkali index were used to analyze the hydrochemistry of the surface water and aquifers. The results show that the surface and groundwater in the research area is generally alkaline, rock weathering process is the main factor influencing the water quality, secondly is evaporation and precipitation, the atmospheric precipitation has little impact. The ion sources of aquifers are mainly silicate, evaporite and carbonate weathering and cation exchange. It is inferred that the hydraulic connection among Ordovician aquifer, surface water, Quaternary and the 14th limestone aquifers is close, Jurassic sandstone aquifer and No.3 coal roof sandstone aquifer have certain hydraulic connection. It is predicted that in the future, the first and the third mining areas will be affected by Ordovician water greater, then the fourteenth mining area, and the affection for the fourth mining areas is low. More attention must be paid to prevention in advance.

In order to grasp the groundwater chemistry characteristics and water quality in the Dingbian area, the collected 93 groundwater samples were used to assess the groundwater quality, water chemistry characteristics and human health risks caused by nitrate pollution by using WQI water quality index method, human health risk evaluation model, ion ratio method, Piper trilinear diagram and Gibbs model. The results show that the water chemistry in the study area is not significantly affected by nitrate contamination and it is mainly affected by evaporation and crystallization, dissolution and filtration and alternate cation adsorption. The groundwater quality in the study area is generally poor, which is mainly influenced by geological conditions and human activities, among which, NO-3 pollution is more serious. The water quality is gradually improved from south to north and from mountainous areas to plains. Nitrate pollution in groundwater can pose a threat to human health and children have a higher health risk due to nitrate production than adults. [ABSTRACT FROM AUTHOR]

Water-derived high iodine groundwater is a typical primary low-quality water, which poses a serious threat to drinking water safety. Taking the pore water in the central Taiyuan Basin as the research object, the characteristics of high iodine groundwater in the study area were analyzed by collecting 57 sets of groundwater samples in the study area, and the characteristics of high iodine groundwater in the study area were analyzed by comprehensively using the methods of Piper three-line diagram, correlation analysis and element ratio, and the enrichment process was discussed. The results show that the excessive iodine content in groundwater mainly occurs in the pore water of the alluvial plain, and the maximum I-mass concentration is 1128.0 μg/L; the horizontal zonation of high-iodine groundwater is obvious, and the I-mass concentration gradually increases along the groundwater flow direction; the vertical distribution is The characteristics show that with the increase of the burial depth of the water-bearing rock group, the average mass concentration of I- gradually decreases; the hydrochemical type of the high-iodine groundwater is mainly HCO3-Na type, and the groundwater components related to I- are Na+, TDS, Cl -, TOC, HCO-3, pH and ORP; alkaline weakly reducing sedimentary environment, rock weathering, groundwater runoff intensity, organic matter degradation, and competitive adsorption are the natural factors for iodine enrichment in pore water in Taiyuan Basin. Induced overcurrent recharge and stratigraphic mining are important external causes of iodine enrichment in pore water in the Taiyuan Basin. [ABSTRACT FROM AUTHOR]

For problems of existing discrimination methods of water inrush source based on hydrochemical characteristics such as complex process, difficulty to distinguish single water inrush point, neglecting the correlation among hydrochemical characteristics, large calculation amount and so on, a discrimination method of mine water inrush source based on Bayes-extension discrimination method was proposed combining with Bayes discrimination method and extension discrimination method. Twenty-six groups of water samples from different aquifers and four groups of water samples to be judged in Pa'er Coal Mine are obtained, the content of SO2-4, Cl-, HCO-3, K++Na+, Mg2+, Ca2+ in the water samples is taken as hydrochemical characteristic indexes, and thus matter-element models of the water samples are established. The correlation degrees between the water samples to be judged and the known water samples are obtained by use of extension discriminant method. The miscalculation loss of Bayes discriminant method and density function of the water samples to be judged with the known water samples are combined to get Bayes-extension solutions. The type of water inrush sample is discriminated according to the minimum value of Bayes-extension solutions. Piper trilinear diagram, extension discriminant method and Bayes-extension discriminant method are adopted separately to discriminate the type of mine water inrush samples. The results show that Piper trilinear diagram is difficult to accurately discriminate a certain type of water samples, extension discriminant method has misjudgment, while Bayes-extension discriminant method can accurately discriminate the type of water inrush sample.

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The formation water characteristics are closely related to hydrocarbon migration and accumulation. The main factors affecting differences of the formation water from the Yan'an and Fuxian Formations are analyzed, based on the vertical and plane distribution characteristics of water type and hydrochemical composition of the formation water. The relationship between formation water characteristics and reservoir distribution and formation is discussed, and the factors that are important to in the process of finding Jurassic reservoirs are clarified in this paper. Study of formation water of the lower Jurassic Yan'an and Fuxian Formations in the Ordos basin reveal the complexity and regularity of the hydrochemical characteristics. The complexity lies in the diversity of formation water and the hydrochemical parameters, such as water salinity, sodium chloride coefficient, metamorphism coefficient, etc., which vary significantly vertically or laterally. The regularity is reflected in that the varying formation hydrochemistry forms zonation, vertically, east-westward, or geomorphologically. It is pointed out that: 1) The mixing and alternation of formation water in different hydrological cycles lead to the vertical differentiation of formation water chemical characteristics. From Fuxian to Y10 to Y9 strata, the salinity of the formation water gradually decreases, the proportion of CaCl2 type water gradually decreases, and the proportion of NaHCO3 type and Na2SO4 type formation water gradually increases. The coefficient of sodium chloride and desulfurization gradually increase, while the coefficient of metamorphism decreases. 2) Structural evolution determines the east-west zonation of the hydrochemical characteristics. The Jurassic strata at the east or west margin of the basin are buried shallowly or exposed where infiltration water supply alternates easily with a relative lower salinity, and the strata at or close to the axis of the Tianhuan depression are buried deeply far away from the supply area, imprisoned in a relatively stagnant environment, making the salinity relatively high. 3) Regionalization of the formation hydrochemical feature changes with geomorphology of the Fuxian Formation-Yan10 member and is strengthened by the water-rock reaction during the diagenesis process. In the river developed area, formation water salinity is low. In the direction of the slope, terrace, and highland, it increases gradually, while the coefficient of the sodium chloride and desulfurization decreases, and the coefficient of metamorphism increases by degrees. Formation water type changes from Na2SO4 or NaHCO3 to CaCl2. 4) The terraces, slopes, and channel bars have the advantage of reservoir formation in terms of the infiltration water alternating extent, hydrodynamics, lithologic association, and low-amplitude structural trap development conditions, and they are the favorable targets prediction method of Jurassic Palaeogeomorphic reservoir is summarized. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Since great breakthrough was made in purifying lithium carbonate from brine with high content of magnesium and low content of lithium, extracting lithium from brine has obtained increasing attention in China. Potassium-rich brine in the northeastern Sichuan contains many kinds of rare metals such as lithium which is urgently demanded in strategic emerging industries, while associated lithium resources of potassium-bearing brine are rarely considered in previous studies. A borehole(ZK001)with the depth of 3 227 m was arranged in deep exploration project in Xuanhan area of the northeastern Sichuan, of which the main goal is to investigate lithium-bearing brines in the deep. Analysis of fluids during drilling(conventional circulating drilling gas)is a main method of conventional real-time monitoring of wellhead fluids. As a result of lithium’s active property, it is difficult to reveal enrichment features of lithium by gas component only. Fluids of borehole ZK001(include deep brine, fluids during drilling, drilling-washing water), surface water and groundwater around borehole ZK001 were collected and analyzed; the characteristics of fluids during drilling were obtained for the first time; and the vertical variations of lithium and other components of drilling fluids in borehole ZK001 were summarized. The lithium concentrations in different types of water around borehole ZK001 show a rule that deep brine, drilling-washing water, fluids during drilling, groundwater, and surface water in descending order. By comparing the profile characteristics of the composition of fluids during drilling in borehole ZK001, it is discovered that lithium concentration of fluids during drilling in the depth of 0-500 m is relatively high while the ratio of Mg/Li is low. It is revealed that lithium concentration of fluids during drilling is proportional to the depth, and the ratio of Mg/Li is inversely proportional to depth. Lithium concentration of yellow brine collected at the depth of 3 000 m from borehole ZK001 is 10 556 μg·L-1(the ratio of Mg/Li is 33.92), which almost reaches the half of the cut-off grade(24 599 μg·L-1). In addition, Na, K, Rb, Sr components of the yellow brine from borehole ZK001 reach industrial grade. These features of fluids from borehole ZK001 will provide scientific support for future arrangement in drilling engineering. [ABSTRACT FROM AUTHOR]

As one of the globally largest cities suffering from severe water shortage, Beijing is highly dependent on groundwater supply. Located northeast of Beijing, the Pinggu district is an important emergency-groundwater-supply source. This area developed rapidly under the strategy of the integrated development of the Beijing–Tianjin–Hebei region in recent years. It is now important to evaluate the spatiotemporal variations in groundwater quality. This study analyzed groundwater-chemical-monitoring data from the periods 2014 and 2017. Hydrogeochemical analysis showed that groundwater is affected by calcite, dolomite, and silicate weathering. Self-organizing map (SOM) was used to cluster sample sites and identify possible sources of groundwater contamination. Sample sites were grouped into four clusters that explained the different pollution sources: sources of industrial and agricultural activities (Cluster I), landfill sources (Cluster II), domestic-sewage-discharge sources (Cluster III), and groundwater in Cluster IV was less affected by anthropogenic activities. Compared to 2014, concentrations of pollution indicators such as Cl−, SO42−, NO3−, and NH4+ increased, and the area of groundwater affected by domestic sewage discharge increased in 2017. Therefore, action should be taken in order to prevent the continuous deterioration of groundwater quality.

The Yellow River in Inner Mongolia was selected as the study area in this study. In July (wet season) and October (dry season) of 2021, the acquisition of seasonal rivers, the Yellow River tributaries and precipitation, the Yellow River, Wuliangsuhai, Lake Hasuhai, Lake Daihai, an irrigation canal system, and underground water and sea water samples were collected to test the water chemical composition and hydrogen and oxygen isotopic values of different water types. Using the Piper triplot, Gibbs plot, ion ratio, and MixSIAR model methods, the evolution of water chemistry in the Mongolian section of the Yellow River Basin was analyzed, and the transformation relationship between precipitation, surface water, and groundwater was revealed. The results showed that both groundwater and surface water in the study area were slightly alkaline; the dominant anion in water was Cl - , and the dominant cation was Na + . The main hydrochemical types of surface water were Cl·SO 4 -Na·Mg and SO 4 ·HCO 3 -Na·Mg, whereas those of groundwater were Cl·SO 4 -Na·Mg and SO 4 ·HCO 3 -Na·Ca. Groundwater Ca 2+ and Mg 2+ were primarily derived from the dissolution of silicate and evaporite, and surface water Ca 2+ and Mg 2+ were primarily derived from carbonate karst dissolution and carbonate and sulfuric acid in water participating in the dissolution process of carbonate and sulfide minerals. Na + and Cl - in different water bodies were all affected by anthropogenic pollution sources. Owing to the seasonal effect, δ D and δ 18 O of surface water and groundwater were higher in the wet season than in the dry season. The results showed that surface water was affected by evaporative fractionation after receiving precipitation recharge, and the groundwater recharge sources were complex. The MixSIAR model revealed that surface water was the main recharge source of groundwater, accounting for 52.4%-62.2% of the total recharge, and atmospheric precipitation was the main recharge source of surface water, accounting for 85.4%-97.1% of the total recharge.

Goaf water in mining areas is widely found in China's coal mines. To clarify the hydrogeochemical characteristics of goaf water and the influence mechanism of water-rock interaction and further reveal microbial action on the formation of goaf water quality, the goaf water in the Menkeqing coal mine was taken as the object, and physical modeling was used to simulate the process of the real goaf changing from an oxygen-sufficient environment to an anoxic environment with the rise of groundwater level in this work. The experimental results showed that the water-rock interaction in the goaf was mainly the dissolution-precipitation of minerals in the rocks of the caving zone and fracture zone, cation exchange, and oxidation of pyrite in the coal layer. The primary sources of Na + and K + in the goaf water were the dissolution and reverse ion exchange of silicate minerals such as albite and potassium feldspar, while Ca 2+ and Mg 2+ mainly from the dissolution of minerals such as calcium feldspar, calcite, and chlorite. The oxidation of pyrite in coal was the main reason for the increase in SO 4 2- concentration, the enhancement of reduction, and the decrease in pH and DO (dissolved oxygen) in the goaf water. Relative abundance of sulfate-reducing bacteria (SRB) in goaf (e.g., Desulfosporosinus, Desulfobacterium, etc.) increased gradually, inhibiting the increase in SO 4 2- concentration in goaf water through the devulcanization of SRB. The inverse hydrogeochemical modeling was performed using PHREEQC for two stages of the simulation experiment: 0-30 days and 30-300 days. The simulation results show that the water-rock action in the formation of goaf water mainly occurred in the simulation experiment's early stage (0-30 days), and the mineral dissolution is dominant throughout the experimental stage. The results of the study provide a theoretical reference for the prediction of highly mineralized water pollution in goaf and its prevention and control.

• Investigation into eastern Himalayan syntaxis geothermal field in southern Tibet. • This geothermal field is a typical high-temperature magmatic geothermal field. • Seven conceptual patterns of the evolution of geothermal waters were established. • Brittle tensional faults cross-cutting the IYSZ control hydrothermal activity. • Hydrothermal activity is closely related to Cenozoic magmatic activity. The eastern Himalayan syntaxis is the easternmost end of southern Tibet and undergoing the continental Indian-Eurasian collision. The occurrence of large amounts of geothermal waters with high temperatures along the regional active faults is a clear manifestation of an abnormal thermal structure of the crust. In order to further complement the distribution characteristics of hydrothermal activity in southern Tibet, geothermal waters were collected and the hydrochemical characteristics and genetic mechanisms were analyzed. In the eastern Himalayan syntaxis geothermal field, geothermal waters show different compositional features. The major ions are Na+, Ca2+ and HCO 3 −, SO 4 2−, which are mainly controlled by water-rock interaction. Two peculiar hydrochemical characteristics of geothermal waters are proposed: ⅰ) the Cl− concentration of three water samples is abnormally high due to the likely contribution of magmatic water; ⅱ) the other three have a lower Cl− concentration but higher temperature because of flashing steam heating. The positive correlations between B, Li and Cl concentrations indicate that the geothermal waters originate in a parent geothermal liquid. The enthalpy-chloride diagram shows that the Cl− concentration and the enthalpy of the parent geothermal liquid are 283 mg/L and 1732 J/g (matching a temperature of 413.74 °C), respectively. Four cooling processes for the geothermal waters which ascend from reservoirs to surface were suggested, i.e., conductive cooling, adiabatic cooling, mixing with cold groundwater and the combination of these processes. The partial melting derived from crustal anatexis or crust-mantle mixing is the heat source for this geothermal field. The oxygen and hydrogen isotopic ratios indicate that the geothermal waters are meteorically-fed. The meteoric waters infiltrate via brittle tensional small-scale faults. According to the results of hydrochemical analysis, the evolution patterns of geothermal waters have been further summarized into seven patterns. Except for Pattern g, Patterns a to f are associated with the parent geothermal liquid. [ABSTRACT FROM AUTHOR]

As one of the globally largest cities suffering from severe water shortage, Beijing is highly dependent on groundwater supply. Located northeast of Beijing, the Pinggu district is an important emergency-groundwater-supply source. This area developed rapidly under the strategy of the integrated development of the Beijing–Tianjin–Hebei region in recent years. It is now important to evaluate the spatiotemporal variations in groundwater quality. This study analyzed groundwater-chemical-monitoring data from the periods 2014 and 2017. Hydrogeochemical analysis showed that groundwater is affected by calcite, dolomite, and silicate weathering. Self-organizing map (SOM) was used to cluster sample sites and identify possible sources of groundwater contamination. Sample sites were grouped into four clusters that explained the different pollution sources: sources of industrial and agricultural activities (Cluster I), landfill sources (Cluster II), domestic-sewage-discharge sources (Cluster III), and groundwater in Cluster IV was less affected by anthropogenic activities. Compared to 2014, concentrations of pollution indicators such as Cl−, SO42−, NO3−, and NH4+ increased, and the area of groundwater affected by domestic sewage discharge increased in 2017. Therefore, action should be taken in order to prevent the continuous deterioration of groundwater quality. [ABSTRACT FROM AUTHOR]