The Experts below are selected from a list of 1725 Experts worldwide ranked by ideXlab platform
Yanxin Wang - One of the best experts on this subject based on the ideXlab platform.
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Hydrogeochemistry of high fluoride saline groundwater in the yuncheng basin northern china
E3S Web of Conferences, 2019Co-Authors: Xubo Gao, Yanxin Wang, Ken W F HowardAbstract:The presence of saline groundwater has become one of the most acute problems for water resource management worldwide, since it causes deterioration in water quality and endangers future exploitation of groundwater resources. In addition, high levels of groundwater salinity are often associated with an increase in the concentrations of fluoride (F). Diverse mechanisms govern salts and fluoride enrichment in groundwater. In this case, saline groundwater with elevated fluoride (up to 14.1 mg/L) in the Yuncheng Basin (YB) was investigated. The research shows: (i) large-scale contamination of F in groundwater is closely associated with groundwater salinization processes in the area; (ii) groundwater with high F concentrations has distinctive major ion chemistry: Na-rich and Ca-poor with a high pH and HCO 3 - content. The major ion chemistry and pH are controlled by mineral dissolution, cation exchange, and evaporation in the aquifer systems which are also important for F mobilization.
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Hydrogeochemistry of high fluoride groundwater at yuncheng basin northern china
Science of The Total Environment, 2015Co-Authors: Xubo Gao, Yanxin WangAbstract:Abstract Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F− concentration of up to 14.1 mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F− concentrations above the WHO provisional drinking water guideline of 1.5 mg/L. Groundwater with high F− concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO3− content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F− mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F− in groundwater of the intermediate and deep aquifers.
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Hydrogeochemistry and arsenic contamination of groundwater in the jianghan plain central china
Journal of Geochemical Exploration, 2014Co-Authors: Yiqun Gan, Yanxin Wang, Yamin Deng, Yanhua Duan, Xinxin Guo, Xufeng DingAbstract:Abstract Although high arsenic groundwater has been reported in the northwest of China, no data describing groundwater arsenic in the river plains of central China have been published to date. In this study, 186 groundwater samples were collected from the Jianghan Plain between the Yangtze and Han rivers. Major constituents, trace elements, dissolved organic carbon (DOC), and stable hydrogen and oxygen isotopic compositions were analyzed to characterize groundwater chemistry and evaluate the factors controlling arsenic concentration and distribution in the plain. The results show that the groundwater is mainly HCO 3 –CaMg type with circum-neutral pH and moderate to high electrical conductivity. Negative Eh and high concentrations of DOC clearly indicate strongly reducing conditions with abundant organic matter in the groundwater aquifers. The characteristics of H/O stable isotopes demonstrate that the groundwater in the study area is recharged by local precipitation and there is a slow evaporation effect. Groundwater with high arsenic was found in wells at depths of 10 to 45 m along rivers. About 87% of the groundwater samples had As concentrations exceeding the WHO recommended value of 10 μg/L, up to 2330 μg/L. High concentrations of dissolved Fe (maximum value, 23 mg/L), Mn (maximum value, 5 mg/L) and P (maximum value, 4 mg/L) were also observed in groundwater. Among the wells, 89% and 98% exceeded the WHO guideline for Fe and Mn, respectively. The concentrations of total As measured in sediments from the Jianghan Plain were much higher than the global average, ranging from 11 to 108 mg/kg. All of the sediments had high Fe (Fe 2 O 3 4–9%) and Mn (504–1064 mg/kg) levels, which is consistent with Fe and Mn oxides/hydroxides considered to be the dominant minerals containing As in sediments and the main sources for As in groundwater of the Jianghan Plain. The main potential mechanism for the release of As is the reductive dissolution of Fe and Mn oxides/hydroxides under reducing conditions, while microbial degradation of organic matter may also facilitate the release of arsenic into groundwater. The competitive effects of other anions may also be important factors since the concentrations of DOC, HCO 3 − and dissolved P were high in many of the groundwater samples.
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Hydrogeochemistry of high fluoride groundwater in shallow aquifers hangjinhouqi hetao plain
Journal of Geochemical Exploration, 2013Co-Authors: Yanxin Wang, Huimei Shan, Yamin DengAbstract:Abstract Hydrochemical characteristics of groundwater, the lithological features of the aquifer sediments and fluoride in rocks were studied to determine the distribution and genesis of high fluoride groundwater (> 1.5 mg/L) in Hangjinhouqi, which is an endemic fluorosis areas. Groundwater with high fluoride (> 1.5 mg/L) is mainly of HCO3–Na or HCO3–Cl–Na type for both fresh and brackish water. Different from other halide ions of Cl−, Br− and I−, F− in groundwater decreased with the TDS. Analysis of fluorine in rocks showed that the average of total fluorine in rocks in Hangjinhouqi (1278.84 mg/kg) is much higher than the background value of Inner Mongolia (316.2 mg/kg). During long-term water–rock interaction, fluoride in these rocks from Yin Mountains will be released out and then accumulated in the groundwater of sand or clay (silty clay) aquifers in the Hangjinhouqi area. All the water samples fall below the Ksp curve of CaF2. Due to CaF2 solubility control, Na-predominant water is favorable for F enrichment, that's why groundwater with high fluoride displayed low TDS in the study area.
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Hydrogeochemistry and environmental impact of geothermal waters from yangyi of tibet china
Journal of Volcanology and Geothermal Research, 2009Co-Authors: Qinghai Guo, Yanxin Wang, Wei LiuAbstract:Abstract The Yangyi geothermal field, located 72 km northwest to Lhasa City, capital of Tibet, has a high reservoir temperature up to at least 207.2 °C. The geothermal waters from both geothermal wells and hot springs belong to the HCO 3 (+CO 3 )–Na type. Factor analysis of all the chemical constituents shows that they can be divided into two factors: F 1 factor receives the contributions of SO 4 2− , Cl − , SiO 2 , As, B, Na + , K + , and Li + ; whereas F 2 factor is explained by HCO 3 − , F − , CO 3 2− , Ca 2+ , and Sr 2+ . The F 1 factor can be regarded as an indicator of the reservoir temperature distribution at Yangyi, but its variable correlation with the results of different geothermometers (Na–K, quartz and K–Mg) does not allow one to draw further inferences. Different from F 1 , the F 2 factor is an indicator of a group of hydrogeochemical processes resulting from the CO 2 pressure decrease in geothermal water during its ascent from the deep underground, including transformation of HCO 3 − to CO 3 2− , precipitation of Ca 2+ and Sr 2+ , and release of F − from some fluoride-bearing minerals of reservoir rocks. The plot of enthalpy vs. chloride, prepared on the basis of Na–K equilibrium temperatures, suggests that a parent geothermal liquid (PGL) with Cl − concentration of 185 mg/L (that of sample YYT-8) and enthalpy of 1020 J/g (corresponding to a temperature of 236–237 °C, i.e., somewhat higher than that of sample YYT-6) is present in the geothermal reservoir of the Yangyi area, below both the Qialagai valley and the Bujiemu valley, although the samples less affected by mixing and cooling (YYT-6 and YYT-7) come from the second site. The discharge of geothermal waters with high contents of toxic elements such as B, As and F into the Luolang River, the only drinking water source for local residents, has caused slight pollution of the river water. Great care should therefore be taken in the geothermal water resource management at Yangyi.
Xubo Gao - One of the best experts on this subject based on the ideXlab platform.
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Hydrogeochemistry of high fluoride saline groundwater in the yuncheng basin northern china
E3S Web of Conferences, 2019Co-Authors: Xubo Gao, Yanxin Wang, Ken W F HowardAbstract:The presence of saline groundwater has become one of the most acute problems for water resource management worldwide, since it causes deterioration in water quality and endangers future exploitation of groundwater resources. In addition, high levels of groundwater salinity are often associated with an increase in the concentrations of fluoride (F). Diverse mechanisms govern salts and fluoride enrichment in groundwater. In this case, saline groundwater with elevated fluoride (up to 14.1 mg/L) in the Yuncheng Basin (YB) was investigated. The research shows: (i) large-scale contamination of F in groundwater is closely associated with groundwater salinization processes in the area; (ii) groundwater with high F concentrations has distinctive major ion chemistry: Na-rich and Ca-poor with a high pH and HCO 3 - content. The major ion chemistry and pH are controlled by mineral dissolution, cation exchange, and evaporation in the aquifer systems which are also important for F mobilization.
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Hydrogeochemistry of high fluoride groundwater at yuncheng basin northern china
Science of The Total Environment, 2015Co-Authors: Xubo Gao, Yanxin WangAbstract:Abstract Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F− concentration of up to 14.1 mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F− concentrations above the WHO provisional drinking water guideline of 1.5 mg/L. Groundwater with high F− concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO3− content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F− mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F− in groundwater of the intermediate and deep aquifers.
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fluoride and arsenic Hydrogeochemistry of groundwater at yuncheng basin northern china
Geochemistry International, 2014Co-Authors: Anas M Khair, Xubo Gao, Yanxin WangaAbstract:High fluoride and arsenic concentrations in groundwater have led to serious health problems to local inhabitants at Yuncheng basin, Northern China. In this study, groundwater with high fluoride and arsenic concentration at Yuncheng basin was investigated. A majority of the samples (over 60%) belong to HCO3 type water. The predominant water type for the shallow groundwater collected from southern and eastern mountain areas was Ca/Mg-Ca-HCO3 types. For the shallow groundwater from flow through and discharge area it is Na-HCO3/SO4-Cl/SO4/Cl type. The predominant water type for the intermediate and deep groundwater is of Na/Ca/Mg-Ca-HCO3 type. According to our field investigation, fluoride concentration in groundwater ranges between 0.31 and 14.2 mg/L, and arsenic concentration ranges between 0.243 and 153.7 μg/L. Out of seventy collected groundwater samples, there are 31 samples that exceed the World Health Organization (WHO) standard of 1.5 mg/L for fluoride, and 15 samples exceeds the WHO standard of 10 μg/L for arsenic. Over 40% of high fluoride and arsenic groundwater are related to the Na-HCO3 type water, and the other fifty percent associated with Na-SO4-Cl/HCO3-SO4-Cl type water; little relation was found in calcium bicarbonate type water. A moderate positive correlation between fluoride and arsenic with pH were found in this study. It is due to the pH-dependent adsorption characteristics of F and As onto the oxide surfaces in the sediments. The observed negative correlation between fluoride and calcium could stem from the dissolution equilibrium of fluorite. The high concentration of bicarbonate in groundwater can serve as a powerful competitor and lead to the enrichment of fluoride and arsenic in groundwater. Most of the groundwater with high fluoride or arsenic content has nitrate content about or over 10 mg/L which, together with the observed positive correlations between nitrate and fluoride/arsenic, are indicative of common source of manmade pollution and of prevailing condition of leaching in the study area.
Zhonghe Pang - One of the best experts on this subject based on the ideXlab platform.
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quantitative calculation for the contribution of acid rain to carbonate weathering
Journal of Hydrology, 2019Co-Authors: Tianming Huang, Yin Long, Zhonghe PangAbstract:Abstract Carbonate weathering by CO2 is considered to play an important role in the global carbon cycle. In acid rain-affected areas, the carbon cycle can be impacted by acid rain weathering. When previous studies have considered all possible weathering processes including H2SO4 in rainfall, sulfide oxidation and agricultural activities, this study proposed a geochemical method to specifically calculate the extent of carbonate weathering by acid rain using hydrogeochemical data from karstic spring and rainfall. This method has considered the H concentration and nitrification of NH4 in rain during recharge, and provided the upper limit of the weathering amount. Seasonal sampling for spring (wet and dry season) was conducted from a typical carbonate area in Jiaoshi, Chongqing, SW China, with annual rain pH values ranging from 3.94 to 4.70. The major Hydrogeochemistry types of spring are HCO3–Ca and HCO3–Ca·Mg. The average proportion of carbonate weathering by acid rain is estimated to be 36 ± 15%. The quantitative geochemical method provided in this study is important for understanding the hydrogeochemical processes in acid rain areas and for calculating CO2 sources & sinks of carbonate weathering.
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Hydrogeochemistry and groundwater circulation in the xi an geothermal field china
Geothermics, 2005Co-Authors: Dajun Qin, Zhonghe Pang, Jeffrey V TurnerAbstract:Abstract Geothermal waters from the Tertiary aquifers located at 1000–3000 m beneath Xi’an city, Shaanxi Province, China, show unique isotopic composition as compared to local groundwaters from shallower Quaternary aquifers. Positive oxygen shifts of as much as 8‰ VSMOW are observed, while the corresponding δ 2 H values remain essentially constant at about −80‰ VSMOW, which is significantly different from those of waters in the Quaternary aquifers with a mean δ 2 H value of −60‰ VSMOW. The strong 18 O shift is a result of isotope exchange between geothermal water and carbonate minerals such as calcite over a residence time of several thousand years up to 30,000 years, based on 14 C dating. A comparison of the isotopic composition of geothermal waters with neighbouring groundwater units on both sides of the Guanzhong Basin indicates that the geothermal reservoirs are recharged by rain that falls on the northern slope of the Qinling Mountains, south of the Xi’an geothermal field, but not from the North Mountains to the north of the field. Based on chemical geothermometers the highest temperature estimated for the Tertiary aquifers of the Xi’an area is around 130 °C.
Yamin Deng - One of the best experts on this subject based on the ideXlab platform.
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Hydrogeochemistry and arsenic contamination of groundwater in the jianghan plain central china
Journal of Geochemical Exploration, 2014Co-Authors: Yiqun Gan, Yanxin Wang, Yamin Deng, Yanhua Duan, Xinxin Guo, Xufeng DingAbstract:Abstract Although high arsenic groundwater has been reported in the northwest of China, no data describing groundwater arsenic in the river plains of central China have been published to date. In this study, 186 groundwater samples were collected from the Jianghan Plain between the Yangtze and Han rivers. Major constituents, trace elements, dissolved organic carbon (DOC), and stable hydrogen and oxygen isotopic compositions were analyzed to characterize groundwater chemistry and evaluate the factors controlling arsenic concentration and distribution in the plain. The results show that the groundwater is mainly HCO 3 –CaMg type with circum-neutral pH and moderate to high electrical conductivity. Negative Eh and high concentrations of DOC clearly indicate strongly reducing conditions with abundant organic matter in the groundwater aquifers. The characteristics of H/O stable isotopes demonstrate that the groundwater in the study area is recharged by local precipitation and there is a slow evaporation effect. Groundwater with high arsenic was found in wells at depths of 10 to 45 m along rivers. About 87% of the groundwater samples had As concentrations exceeding the WHO recommended value of 10 μg/L, up to 2330 μg/L. High concentrations of dissolved Fe (maximum value, 23 mg/L), Mn (maximum value, 5 mg/L) and P (maximum value, 4 mg/L) were also observed in groundwater. Among the wells, 89% and 98% exceeded the WHO guideline for Fe and Mn, respectively. The concentrations of total As measured in sediments from the Jianghan Plain were much higher than the global average, ranging from 11 to 108 mg/kg. All of the sediments had high Fe (Fe 2 O 3 4–9%) and Mn (504–1064 mg/kg) levels, which is consistent with Fe and Mn oxides/hydroxides considered to be the dominant minerals containing As in sediments and the main sources for As in groundwater of the Jianghan Plain. The main potential mechanism for the release of As is the reductive dissolution of Fe and Mn oxides/hydroxides under reducing conditions, while microbial degradation of organic matter may also facilitate the release of arsenic into groundwater. The competitive effects of other anions may also be important factors since the concentrations of DOC, HCO 3 − and dissolved P were high in many of the groundwater samples.
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Hydrogeochemistry of high fluoride groundwater in shallow aquifers hangjinhouqi hetao plain
Journal of Geochemical Exploration, 2013Co-Authors: Yanxin Wang, Huimei Shan, Yamin DengAbstract:Abstract Hydrochemical characteristics of groundwater, the lithological features of the aquifer sediments and fluoride in rocks were studied to determine the distribution and genesis of high fluoride groundwater (> 1.5 mg/L) in Hangjinhouqi, which is an endemic fluorosis areas. Groundwater with high fluoride (> 1.5 mg/L) is mainly of HCO3–Na or HCO3–Cl–Na type for both fresh and brackish water. Different from other halide ions of Cl−, Br− and I−, F− in groundwater decreased with the TDS. Analysis of fluorine in rocks showed that the average of total fluorine in rocks in Hangjinhouqi (1278.84 mg/kg) is much higher than the background value of Inner Mongolia (316.2 mg/kg). During long-term water–rock interaction, fluoride in these rocks from Yin Mountains will be released out and then accumulated in the groundwater of sand or clay (silty clay) aquifers in the Hangjinhouqi area. All the water samples fall below the Ksp curve of CaF2. Due to CaF2 solubility control, Na-predominant water is favorable for F enrichment, that's why groundwater with high fluoride displayed low TDS in the study area.
Martínez Florentino, Ana Karen - One of the best experts on this subject based on the ideXlab platform.
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Characterizing the Hydrogeochemistry of two low-temperature thermal systems in Central Mexico.
Journal of Geochemical Exploration, 2018Co-Authors: Morales-arredondo Ivan, Esteller Alberich, Maria Vicenta, Armienta Hernandez, María Aurora, Martínez Florentino, Ana KarenAbstract:Two low-temperature geothermal systems located at the Trans-Mexican Volcanic Belt with presence of fluoride and arsenic were studied with the aim to determine hydrogeochemical indicators of the toxic elements' presence, and to propose adequate geothermometers. The hydrogeological and geochemical study was carried out in Ixtapan de la Sal and Tonatico (IxS-T) and Santa Cruz de Juventino Rosas (JR), both located at the limits of the Trans-Mexican Volcanic Belt (TMVB). In these regions, low-temperature geothermal activity is present (T = 32–47 °C), and various fault and fracture systems have been identified. Several faults are active, enabling the upward flow of deep geothermal water. The geothermal waters of IxS-T manifest in the form of springs and have high Na+ and Cl− concentrations, whereas those of JR are captured in wells and mainly present high Na+ and HCO3 – concentrations. The hydrochemistry of water samples was analyzed to determine the dominant hydrogeochemical processes in both regions. These data were also useful for understanding the natural origin of the high levels of arsenic and fluoride reported in the water, which are likely due to mineral dissolution processes. The concentrations of these elements surpassed the permissible limits according to Mexican law (Astot = 0.025 mg/L; F− = 1.5 mg/L) and represent a toxicity risk for the local populations. The groundwater at JR supplies all needs of the local population, while the water at IxS-T is mainly used for recreational and health spa purposes. Increasing trends of As and F− in the sedimentary aquifer of IxS-T are related with the increase in TDS, Cl−, HCO3 – and SiO2, while silicate alteration releasing Na and HCO3 – are related with As and F− presence in the volcanic aquifer of JR. Reservoir temperature was adequately estimated with K2 /Mg and Na-K-Ca (Mg corrected) geothermometers at IxS-T, and with chalcedony and quartz geothermometers at JRUAEM 3716/201
