Stable Isotope and Hydrochemical Evolution of Groundwater in Mining Area of the Changzhi Basin, Northern China

Stable Isotope and Hydrochemical Evolution of Groundwater in Mining Area of the Changzhi Basin, Northern China | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Stable Isotope and Hydrochemical Evolution of Groundwater in Mining Area of the Changzhi Basin, Northern China Chunchao Zhang, Xiangquan Li, Jianfei Ma, Zhenxing Wang, Xinwei Hou This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-823775/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract The Changzhi Basin of China is an economically and ecologically important area with intensive human activities. To foster the sustainable development of groundwater resources and the economy, a total of 117 groundwater samples were collected in shallow and deep aquifers, including 91 2 H and 18 O isotope samples, to improved understanding of the natural geochemical processes and the impacts of anthropogenic activities on the groundwater chemistry. Synthetical application of the stable isotopes, Piper diagram, Gibbs diagram, ionic ratios and saturation indices to data analysis led to identification of hydrochemical zones for both aquifers from west to east of the basin. Isotopic analyses suggested that the groundwater recharge mainly comes from infiltration of rain water, hydraulic interaction between surface water and shallow groundwater, and lateral recharge from fissure water at the edge of the basin. The predominant natural geochemical processes include mineral dissolution in conjunction with the cation exchange. The excess deuterium method revealed that mineral dissolution contributed 81%–98% to the salinity of shallow groundwater and 84%–98% to the salinity of deep groundwater. Anthropogenic activities are secondary contributions to the hydrochemical evolution with fertilizer application, human waste and sewage discharges causing an increase in NO 3 -N content and coal mining activities affecting the ion content of Na + , Cl - , SO 4 2- , and HCO 3 - in the groundwater. Geology Environmental Chemistry Groundwater Hydrogeochemistry Stable isotopes Hydrochemical mechanisms Anthropogenic activities Coal mining Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 1. Introduction Groundwater resources are increasingly exploited for industrial and agricultural purposes in many arid and semi-arid regions globally (Li et al., 2019 ; Liu et al., 2015 ). In the last few decades, rapid developments in industry, agriculture, and coal mining, together with rapid urban population growth, has led to dramatic changes in water chemistry in many developing countries (Jamshidzadeh and Mirbagheri, 2011 ; Sandow et.al, 2010 ). Water chemistry can be used to facilitate an understanding of the natural geochemical processes and the effects of anthropogenic activities (Liu et al., 2015 ; Selvakumar et al., 2017 ). The study of hydrochemical processes and the factors affecting water quality provides an insight to the controlling mechanisms of groundwater hydrochemistry, and is important for sustainable development and effective protection of groundwater (Tizro and Voudouris, 2008 ; Chang and Wang, 2010 ; Yang et al., 2016 ; Mohanty et al., 2019 ). The combination of hydrogeochemical methods such as the Piper diagram, Gibbs diagram, ionic ratios, and multiple isotopic analyses have been widely used to study hydrochemical evolution (Plummer et al., 1990 ; Marfia et al., 2004 ; Wang et al., 2006 ; Qian et al., 2013 ; Liu et al., 2015 ; Sánchez et al., 2015 ). Isotopic and geochemical indicators often serve as effective methods for solving multiple problems in hydrology and hydrogeology, especially in semi-arid and arid regions (Clark and Fritz, 1997 ; Zang et al., 2018 ). Stable isotopes of H and O are typical tracers for investigating the sources of groundwater recharge and the hydrological cycle because the stable isotopes are constituents of the water molecules (Chen et al., 2012 ; Jia et al., 2017 ). Hydrogeochemical indicators in different water bodies can provide information on the geochemical reactions within the aquifer and on the possible evolutionary pathways of groundwater (Cook and Herczeg, 1999 ; Appelo and Postma, 2004 ). The Changzhi Basin is located in the arid to semi-arid area of northern China. Because of population growth and the increasing development of agricultural and coal mining activities, the demand for groundwater is continually increasing. Groundwater pollution in the Changzhi Basin is, however, increasing as a result of the large-scale and long-term discharge of coal mining water, domestic sewage, and industrial waste water, and the excessive use of fertilizers. Various studies on karst groundwater in the Changzhi Basin have been conducted, and were mainly focused on karst spring flow, groundwater quality, and water resource protection (Sun, 2008 ; Chen et al., 2012 ; Yang et al., 2016 ). Studies on groundwater hydrochemistry and evolution processes in the porous media are lacking. The present study addresses this knowledge gap. To obtain a comprehensive understanding of the evolution of groundwater hydrochemistry in the Changzhi Basin, it is necessary to identify the impacts of natural factors and anthropogenic activities on the groundwater hydrochemistry. Consequently, the main objectives of the present study are to: (1) interpret the hydrochemical and stable isotopic characteristics; (2) ascertain the origin of groundwater and reveal the hydrochemical formation mechanisms for both natural geochemical processes and anthropogenic activities; and (3) quantify the contribution of mineral dissolution, evaporation, and cation exchange factors in controlling the chemical composition of groundwater. 2. Regional Hydrogeology The Changzhi Basin is located in the southeast of Shanxi Province (Fig. 1 ), encompassing an area of 1,169 km 2 , and lying between 36°00′ and 36°19′ N and 112°46′ and 113°16′ E. The annual mean air temperature of the study area ranged from 8.9 to 10.9°C over the past 30 years. The average rainfall from 1956 to 2018 was 536 mm, with a range from 264 mm (1965) to 1,056 mm (1971). 60–70% of the annual rainfall was concentrated in July, August, and September. The annual mean water surface evaporation was 1,678 mm, with a maximum of 1,810 mm and a minimum of 1,372 mm. The Zhuozhang River, the main river in the basin, runs from the south to the north. The main tributaries of the Zhuozhang River are the Taoqing, Lanshui, Jianghe, and Yuni Rivers. The Zhangze Reservoir is the only large-scale reservoir in the study area, while there are many medium and small-sized reservoirs, such as the Baojiahe, Tunjiang, and Shencun Reservoirs. Geologically, Changzhi Basin is a Cenozoic fault basin. The main outcropping strata in the study area are of Quaternary (Q) age. Permian (P), Carboniferous (C), and Ordovician (O) strata outcrop locally. The Quaternary sediments are 0–300 m thick, and the sediments thicken from west to east (Fig. 2 ). The main aquifers are in the unconsolidated sediments, and divided into shallow (≤ 50 m in depth) and deep (> 50 m in depth) aquifers. The shallow aquifer is unconfined in alluvial-proluvial sand-gravel layers of the Holocene and Upper Pleistocene. The deep aquifer is confined in silt, sand, and gravel lenses of the Middle and Lower Pleistocene. The unconfined and confined aquifers are separated by a discontinuous aquitard composed of a mudstone layer. The regional groundwater flows towards the Zhangze Reservoir and Zhuozhang River (i.e., from the west, east, and south). 3. Sampling And Analysis 3.1. Sample collection A total of 117 groundwater samples were collected in April and November, 2018. The samples comprised 76 shallow groundwater samples, 36 deep groundwater samples, and 5 mine drainage samples. The sampling locations are shown in Fig. 1 . Mine drainage samples were taken from the water drained from the mines to enable the exploitation of coal-bed methane and coal. Additionally, 24 rainwater samples were collected from central, eastern, and western areas of the basin from July, 2017 to July, 2018 for stable isotope tests; whereas, three of these samples were also used for hydrochemical tests. The samples were filtered through 0.45 µm membranes on site and then stored at 4°C. The bottles were rinsed twice with deionized water before sampling. For cation analysis, water samples were acidified using analytically pure nitric acid to pH < 2. Samples for stable isotope analysis (δ 18 O and δ 2 H) were collected in 50 mL glass bottles, which were sealed with airtight caps. 3.2. Measurement methods Water temperature, pH, and electrical conductivity were directly measured on-site using a HANNA HI 991301 multi-parameter instrument. Major anions, cations and minor elements were analyzed by a Thermo Scientific Dionex ICS-4000 (precision = ± 1%) and PerkinElmer Optima 8300 inductively coupled plasma-optical emission spectrometer (precision = ± 1%) at the Groundwater Mineral Water and Environmental Monitoring Center in the Institute of Hydrogeology and Environmental Geology at the Chinese Academy of Geological Sciences. The analytical precision and electrical balance error of the hydrochemical data were within ± 5%. Stable isotope ratios were expressed in δ (‰) notation and calculated with respect to Vienna Standard Mean Ocean Water (VSMOW). The δ 18 O and δD values in water samples were obtained using a Picarro L2130-i Analyzer at the Institute of Hydrogeology and Environmental Geology at the Chinese Academy of Geological Sciences. The analytical precision for δD was ± 1‰ and for δ 18 O was ± 0.1‰. 4. Results And Discussion 4.1. Hydrochemical characteristics The physicochemical parameters of the water samples are shown in Table 1 ; all water sample data were plotted on Piper diagrams (Fig. 3 a–c). A coefficient of variation (Cv) is commonly used to characterize the stability of a variable: 0 < Cv < 0.1 indicates weak variability; 0.1 < Cv 1.0 indicates wide variability (Yang et al., 2016 ; Zhai et al., 2019 ). 4.1.1. Rain water, surface water, and mine drainage The pH values of rain water ranged from 6.39 to 6.63, indicating weakly acidic conditions. Surface water (pH 7.03–7.94) and mine drainage (pH 7.85–8.90) were generally neutral to weakly alkaline. The concentrations of the chemical components in rain water were, in general, low. Most of the chemical components in surface water and rain water exhibited a weak to medium variability, but a wide variability in mine drainage. The maximum concentrations of total dissolved solids (TDS), Na + , Cl − , and SO 4 2− for mine drainage were 2,901, 1,176, 1,078, and 1,218 mg·L − 1 , respectively, and were significantly greater than the maximum concentrations for surface water and rain water. The chemical components of surface water were dominated by Ca 2+ , Na + , HCO 3 − , SO 4 2− , and Cl − , and the hydrochemical types were complex. The HCO 3 ·SO 4 -Ca·Mg, HCO 3 ·Cl·SO 4 -Ca·Na, HCO 3 -Ca·Na, SO 4 ·Cl-Na·Ca, and HCO 3 ·Cl-Ca types were all identified for surface water. The chemical components of mine drainage were dominated by Na + , HCO 3 − , SO 4 2− , and Cl − , and hydrochemical types were mainly HCO 3 ·Cl-Na and SO 4 -Na. The chemical components of rain water were, however, dominated by Ca 2+ , HCO 3 − , and SO 4 2− , and the hydrochemical type was HCO 3 ·SO 4 -Ca. 4.1.2. Groundwater The pH values of the shallow groundwater ranged from 7.13 to 8.07, and had a mean value of 7.53, which indicates near neutral to weakly alkaline conditions. Total hardness (TH) and TDS of the shallow groundwater varied from 168.1 to 1,889 mg·L − 1 and from 208.8 to 2,559 mg·L − 1 , respectively. The chemical components were dominated by Ca 2+ , HCO 3 − , SO 4 2− , and Cl − . Of the shallow groundwater samples, 51% were of the HCO 3 -Ca type and had a low TDS (mean value = 409.6 mg·L − 1 ); 16% were of the HCO 3 ·SO 4 -Ca/Mg type and had a medium TDS (mean value = 647.6 mg·L − 1 ); and 13% were of the SO 4 ·HCO 3 (SO 4 ·HCO 3 ·Cl)-Ca/Mg type and had a high ion content (mean value = 1,412.5 mg·L − 1 ). Moreover, the SO 4 ·Cl-Ca, Cl·SO 4 -Ca, and HCO 3 ·Cl-Ca type was also identified for shallow groundwater (Fig. 3 b). The Cv values of K + , Cl − , SO 4 2− , and NO 3 − were greater than 1.0, which indicates that these hydrochemical components had a wide variation in spatial distribution. The TDS content gradually increased (from 208.8 to 2,559 mg·L − 1 ) from the west to the east of the basin. In the west of the basin, the chemical type was mainly HCO 3 -Ca. However, in the east of the basin, the chemical types were complex: SO 4 ·HCO 3 -Ca/Mg, SO 4 ·Cl-Ca, Cl·SO 4 -Ca, and HCO 3 ·Cl-Ca were all identified and the TDS values were high (780–2,559 mg·L − 1 ). For deep groundwater, the pH values ranged from 7.04 to 7.97, with a mean value of 7.57, indicating near neutral to weakly alkaline conditions. The TH and TDS of the deep groundwater varied from 177.1 to 1,559 mg·L − 1 and from 240.2 to 2,160 mg·L − 1 , respectively. The chemical components were dominated by Ca 2+ , Mg 2+ , HCO 3 − , and SO 4 2− . Of the deep groundwater samples, 61% were of the HCO 3 -Ca/Mg type and had a low TDS (mean values = 381.8 mg·L − 1 ); 17% were of the HCO 3 ·SO 4 -Ca/Mg type and had a medium TDS (mean values = 653.45 mg·L − 1 ); and 8% were of the SO 4 ·HCO 3 -Ca/Mg type and had a high ion content (mean values = 1,277.4 mg·L − 1 ). Moreover, the HCO 3 ·SO 4 ·Cl-Ca and HCO 3 ·Cl·SO 4 -Ca types were also identified (Fig. 3 c). The Cv values of Cl − , SO 4 2− , and NO 3 − were greater than 1.0, indicating that these hydrochemical components had a wide variation in spatial distribution. The TDS of the deep groundwater gradually increased (from 240.2 to 2,160 mg·L − 1 ) from the west to the east of the basin. In the west and central of the basin, the groundwater is mainly of the HCO 3 -Ca type. However, in the east of the basin, as a result of low discharge and weak self-purification capacity, the SO 4 ·HCO 3 -Ca/Mg, HCO 3 ·SO 4 ·Cl-Ca, and HCO 3 ·Cl·SO 4 -Ca types were all identified for the deep groundwater, which had a high TDS of approximately 800–2,160 mg·L − 1 . The concentrations of minor and trace elements, such as F, Cr, As, Fe, Mn, and Pb, were generally low, and most were not detected. In terms of the Groundwater Quality Standards of China (GB/T 14848 − 2017), values of F, Cr, and As are all below the Chinese III quality standards (1.0 mg·L − 1 for F, 0.05 mg·L − 1 for Cr, and 0.01 mg·L − 1 for As). The concentrations of Fe, Mn, and Pb exceed the III quality standards in some samples. The standards for Fe, Mn, and Pb (0.3 mg·L − 1 for Fe, 0.10 mg·L − 1 for Mn, and 0.01 mg·L − 1 for Pb) were exceeded in samples 6, 7, and 6, respectively. These samples were taken from shallow groundwater. Table 1 Chemical properties and composition of groundwater, surface water, rain water, and mine drainage samples in the Changzhi Basin. n = number of samples; Cv = coefficient of variation; TH = total hardness; TDS = total dissolved solids. Units: pH in units of pH, major ions and minor elements in mg·L − 1 . shallow groundwater(n = 76) deep groundwater(n = 37) surface water(n = 11) rain water(n = 3) mine drainage(n = 5) range average Cv range average Cv range Average Cv range average Cv range average Cv pH 7.13 ~ 8.07 7.53 0.02 7.04 ~ 7.97 7.57 0.03 7.03 ~ 7.94 7.42 0.04 6.39 ~ 6.63 6.47 0.02 7.85 ~ 8.9 8.41 0.05 Hardness 168.1 ~ 1889 547.58 0.68 177.1 ~ 1559 386.17 0.66 136.1 ~ 417.3 267.03 0.38 9.01 ~ 19.52 13.51 0.40 14.01 ~ 360.3 98.98 1.48 TDS 208.8 ~ 2559 744.02 0.71 240.2 ~ 2160 510.86 0.69 190.1 ~ 955 511.47 0.51 27.51 ~ 48.41 34.84 0.34 715 ~ 2901 1607.60 0.58 K + 0.06 ~ 30.08 1.25 3.01 0.14 ~ 2.68 0.58 0.84 1.6 ~ 17.83 7.08 0.86 0.24 ~ 0.78 0.48 0.57 1.63 ~ 22.72 6.49 1.41 Na + 9.08 ~ 165.7 36.67 0.80 8.9 ~ 73.72 24.62 0.64 13.2 ~ 226.2 76.34 0.88 0.39 ~ 1.24 0.75 0.59 265.3 ~ 1176 587.60 0.60 Ca 2+ 56.06 ~ 537.5 159.87 0.66 50.66 ~ 476.1 113.65 0.69 27.56 ~ 115.8 67.62 0.45 3.24 ~ 6.58 4.71 0.36 3.97 ~ 73.3 22.25 1.30 Mg 2+ 6.78 ~ 151.2 36.04 0.77 8.83 ~ 89.86 24.87 0.65 15.78 ~ 40.82 23.84 0.35 0.24 ~ 0.71 0.40 0.66 0.98 ~ 42.99 10.53 1.73 Cl − 7.72 ~ 548 90.28 1.26 5.26 ~ 311 40.11 1.35 13.51 ~ 196.1 80.37 0.70 1.40 ~ 2.45 1.87 0.29 76.42 ~ 1078 303.35 1.43 SO 4 2− 5.38 ~ 720.7 144.64 1.09 6.61 ~ 469.1 90.53 1.16 48.84 ~ 314.5 127.66 0.76 6.27 ~ 11.97 8.64 0.34 2.17 ~ 1218 269.00 1.97 HCO 3 − 157.1 ~ 581.1 305.79 0.29 197.3 ~ 482.8 272.07 0.27 94.07 ~ 290 209.70 0.33 11.72 ~ 24.16 16.85 0.39 363.7 ~ 941.8 689.46 0.37 NO 3 − 1.84 ~ 873.4 102.83 1.37 8.39 ~ 580.9 61.59 1.65 0.2 ~ 86.66 15.42 1.72 3.61 ~ 6.51 5.41 0.29 1.9 ~ 6.67 3.82 0.48 F − 0.29 ~ 0.78 0.47 0.21 0.23 ~ 0.59 0.44 0.19 0.31 ~ 2.02 0.71 0.74 0.21 ~ 0.26 0.24 0.11 1.86 ~ 7.74 4.21 0.54 Cr 6+ <0.004 ~ 0.01 - - <0.004 ~ 0.028 - - <0.004 - - <0.004 - - <0.004 - - As <0.001 ~ 0.037 - - <0.001 - - <0.001 ~ 0.004 - - <0.001 - - <0.001 ~ 0.032 - - Fe <0.01 ~ 0.058 - - <0.01 ~ 1.497 - - <0.01 ~ 0.599 - - <0.01 - - <0.01 ~ 0.09 - - Mn <0.001 ~ 2.331 - - <0.001 ~ 0.17 - - <0.001 ~ 0.134 - - <0.001 - - <0.001 ~ 0.293 - - Pb <0.001 ~ 0.269 - - <0.001 ~ 0.125 - - <0.001 ~ 0.058 - - <0.001 - - <0.001 ~ 0.008 - - Table 2 Isotopic composition of water samples taken in the Changzhi Basin. shallow groundwater deep groundwater surface water rain water mine drainage Min Max Mean Min Max Mean Min Max Mean Min Max Mean Min Max Mean δ 2 H(‰) -76 -51 -66 -74 -53 -68 -63 -46 -52 -104 -11 -45 -84 -59 -73 δ 18 O(‰) -10.1 -6.3 -8.9 -9.9 -6.5 -9.1 -8.3 -5.2 -6.3 -14.1 -2.0 -6.9 -11.4 -7.9 -9.8 4.2. δ 18 O and δ 2 H characteristics and groundwater provenance Stable water isotopes of hydrogen (δ 2 H) and oxygen (δ 18 O) are increasingly being applied as a useful tool for integrating information about hydrological processes across various scales (McDonnell and Beven, 2014 ; Li et al, 2019 ). Table 2 summarizes the isotopic composition of water samples taken in the Changzhi Basin. 4.2.1. Rain water, surface water, and mine drainage The δ 18 O and δ 2 H of rain water, surface water, and mine drainage are plotted in Fig. 4 a. The slope of the local meteoric water line (LMWL, k = 8.12) is similar to the global meteoric water line (GMWL, k = 8.0), and that the compositions of the stable hydrogen and oxygen isotopes are also aligned with the GMWL. The δ 18 O and δ 2 H compositions of rain water range from − 14.1‰ to − 2.0‰ and − 104‰ to − 11‰, respectively, surface water ranges from − 8.3‰ to − 5.2‰ and − 63‰ to − 46‰, respectively, while mine drainage samples range from − 11.4‰ to − 7.9‰ and − 84‰ to − 59‰, respectively (Table 2 ). The surface water and mine drainage samples lie below the LMWL. When compared with the LMWL, the surface water and mine drainage isotopes can be seen to be enriched in heavy isotopes, and are located near the LMWL. This indicates that the surface water and mine drainage are recharged by rain water and have undergone evaporation and condensation, especially in the case of surface water. The mine drainage samples are scattered in the study area and thus could represent different recharge sources (Qian et al., 2013 ). 4.2.2. Groundwater The δ 18 O and δ 2 H of groundwater are plotted in Fig. 4 b. The δ 18 O and δ 2 H compositions of groundwater are located near the LMWL, which indicates that the groundwater is mainly recharged by rain water. The slope of the shallow groundwater line (k = 6.19) is smaller than that of the deep groundwater line (k = 6.41), which means that the groundwater has undergone evaporation during the recharge process, especially in the case of shallow groundwater. The δ 18 O and δ 2 H values for shallow groundwater range from − 10.1‰ to − 6.3‰ and − 76‰ to − 51‰, respectively, while for deep groundwater the corresponding values are − 9.9‰ to − 6.5‰ and − 74‰ to − 53‰, respectively. Some shallow groundwater samples have relatively low stable isotope concentrations and some deep groundwater samples have relatively high concentrations. This may have resulted from the interaction between shallow and deep groundwater. The δ 18 O and δ 2 H values of some shallow groundwater samples are consistent with surface water, indicating an interaction between surface water and shallow groundwater. Because of the lateral recharge from fissure groundwater at the edge of the basin, the δ 18 O and δ 2 H compositions of shallow groundwater are relatively low. 4.3. Hydrochemical evolution processes 4.3.1. Effects of precipitation, evaporation, and rock-type on hydrochemistry A qualitative analysis, using the Gibbs diagram (Gibbs, 1970 ), was carried out to identify the dominant processes affecting evolution. The Gibbs diagram depicts the relative dominance of precipitation, rock weathering, and evaporation in semi-arid and arid regions. The diagrams show the weight ratios of Na + /(Na + +Ca 2+ ) and Cl − /(Cl − +HCO 3 − ) against TDS, as shown in Fig. 5 . Figure 5 b shows that the ratios of Na + /(Na + +Ca 2+ ) are mostly less than 0.5 and that the TDS is mostly low to medium, which indicates that rock weathering is the dominant mechanism in the geochemical evolution of groundwater for both shallow and deep groundwater. The ratios of Na + /(Na + +Ca 2+ ), however, show a wide range of values without any obvious changes in TDS values. This suggests that cation exchange also plays an important role by increasing Na + and decreasing Ca 2+ when geochemical evolution is dominated by rock-weathering processes (Liu et al., 2015 ; Li et al., 2019 ). This occurs because 2 mmol·L − 1 of Na + is exchanged with 1mmol·L − 1 of Ca 2+ during the cation exchange, and the mass concentration of 2 mmol·L − 1 of Na + (46 mg·L − 1 ) is nearly equal to 1mmol·L − 1 of Ca 2+ (40 mg·L − 1 ). Some samples of shallow groundwater, however, are located on the upper right of the Gibbs diagram (Fig. 5 a), and the ratios of Cl − /(Cl − +HCO 3 − ) are greater than 0.5 and the TDS value greater than 1,100 mg·L − 1 . This shows that the groundwater chemistry is controlled not only by rock weathering, but also by evaporation (Xing et al., 2013 ). 4.3.2. Effects of evaporation on groundwater salinity based on stable isotope The deuterium excess, as one of the most important indicators characterizing atmospheric precipitation for comprehensive environmental factors, is capable of quantifying the contribution of evaporation to groundwater salinity (Dansgaard, 1964 ; Li et al., 2019 ; Huang and Pang, 2012 ). In the study area, δ 2 H 0 and δ 18 O 0 were calculated for − 45‰ and − 6.9‰ of local mean rain water, although the δ 2 H 0 and δ 18 O 0 values do not affect the mineral dissolution to total salinity relationship; \({S}_{0}\) , the total salinity of mean rain water, was defined as 0.035 g·L − 1 ; f is the remaining fraction of the reservoir; the average temperature of the groundwater was 14°C and the humidity was about 60%. Thus, the relationship between \(d\) and \(f\) can be established as given in Eq. (1) (Huang and Pang, 2012 ). $$d=\delta {}^{2}H-8\delta {}^{18}O=\left({\delta }^{2}{H}_{0}+1000\right){f}^{({\alpha }^{2}{H}_{0}-1)}-8\left({\delta }^{18}{O}_{0}+1000\right){f}^{\left({\alpha }^{18}{O}_{0}-1\right)}+7000$$ $$=955\times {f}^{-0.08676}-8\times 993.1\times {f}^{-0.01546}+7000 \left(1\right)$$ \(\frac{{S}_{0}}{f}-{S}_{0}\) was the salinity caused by direct evaporation; D was the salinity increased by mineral dissolution, and \(D=S-{S}_{0}-(\frac{{S}_{0}}{f}-{S}_{0})\) (Huang and Pang, 2012 ). As shown in Fig. 6 a, the average total d-excess and TDS for shallow groundwater and deep groundwater are 4.63‰ and 744.02 mg·L − 1 , 4.72‰ and 510.86 mg·L − 1 , respectively. The contribution ratios of mineral dissolution in shallow groundwater and deep groundwater are 81–98% and 84–98%, while the contribution ratio of evaporation is 0.2–4.7% and 0–2.4%. In the study area, most groundwater depths are greater than 5 m, and the groundwater is mainly recharged by rain water and bedrock fissure water, which favors the dissolution of minerals. Most of the water samples indicate no evaporation effects regardless of shallow groundwater or deep groundwater. Figure 6 b and 6 c show that there is an almost exponential positive correlation between TDS and the contribution of mineral dissolution, and an almost exponential negative correlation between TDS and the contribution of evaporation, which indicates that mineral dissolution is the main contributor to the total salinity of groundwater. 4.3.3. Effects of geochemical processes on hydrochemistry The relationship between (Ca 2+ + Mg 2+ ) and (HCO 3 − + SO 4 2− ) concentrations in groundwater samples is close to the carbonate and gypsum dissolution line (1:1 relationship line) if these ions are controlled by carbonate and gypsum equilibrium (Wang et al., 2006 ; Zhang et al., 2015 ). Ion exchange (Ca 2+ and Mg 2+ in groundwater changed by Na + ) tends to shift points to the right in equilibrium plots as a result of an excess of (HCO 3 − + SO 4 2− ) (Belkhiri et al., 2011 ; Liu et al., 2015 ), but reverse ion exchange shifts the points to the left as a result of an excess of (Ca 2+ +Mg 2+ ). As shown in Fig. 7 a, values for most of the deep groundwater samples plot near the 1:1 line, which indicates that the dissolution of carbonate and gypsum is the main geochemical process in deep groundwater. Values for most of shallow groundwater samples are, however, scattered and located above the 1:1 line. This suggests that ion exchange is one of the main geochemical processes occurring in shallow groundwater in addition to the dissolution of carbonate and gypsum. As shown in Fig. 7 b, in the shallow groundwater, the Na + /Cl − mole ratio varies from 0.37 to 13.27, with an average value of 2.07. In the deep groundwater, the ratio ranges from 0.18 to 7.24, with an average value of 1.21. Most of the values for the deep groundwater samples are located near the 1:1 line, which suggests that the dissolution of halite is the major source of Na + and Cl − for deep groundwater. In contrast, most of the shallow groundwater values are scattered and are located below the 1:1 line. This indicates that there are other geochemical processes than halite dissolution leading to an excess of Cl − , such as Ca(Mg)/Na ion exchange. Ion exchange and adsorption are common reactions in the geochemical evolution of groundwater and influence the major ion composition of groundwater (Li et al., 2019 ). Schoeller ( 1967 ) proposed the chloral-alkali index (CAI) to analyze cation exchange and adsorption (Eqs. (2) and (3)). $$CAI1=\frac{{Cl}^{-}-({Na}^{+}+{K}^{+})}{{Cl}^{-}} \left(2\right)$$ $$CAI2=\frac{{Cl}^{-}-({Na}^{+}+{K}^{+})}{{SO}_{4}^{2-}+{HCO}_{3}^{-}+{CO}_{3}^{2-}+{NO}_{3}^{-}} \left(3\right)$$ A positive CAI indicates the exchange of Ca 2+ and Mg 2+ from the rocks with Na + of the water, while a negative CAI indicates the exchange of Na + from the rocks with Ca 2+ and Mg 2+ of the water. Additionally, a diagram of [(Ca 2+ +Mg 2+ ) − (HCO 3 − +SO 4 2− )] versus (Na + −Cl − ) (Eq. (4)) is also commonly used to explain cation exchange in groundwater (Carol et al., 2013 ; Huang et al., 2013 ; Liu et al., 2015 ). The diagram reflects excess Ca 2+ and Mg 2+ gained or lost from calcite, dolomite, and gypsum dissolution or precipitation, and excess Na + gained or lost from NaCl (Farid et al., 2013 ). If cation exchange plays a major role in controlling the major ion composition of groundwater, there will be a linear relationship with a slope close to − 1.0, as expressed by Eq. (4). $$N=\frac{\left({Na}^{+}+{K}^{+}\right)-{Cl}^{-}}{{Ca}^{2+}+{Mg}^{2+}-{(HCO}_{3}^{-}+{SO}_{4}^{2-})} \left(4\right)$$ Figure 8 a shows that both positive and negative ion exchange occurs in groundwater. For shallow groundwater, the positive ion exchange was slightly dominant, and accounted for 51.3% of the ion exchange. This process mainly occurred at the central of the Changzhi Basin, which have a slower runoff and more shallow groundwater compared with the edge of the basin, leads to the large Na + content in the water displaced part of Ca 2+ in the aquifer. In the edge part of the basin, the cations in the groundwater are dominated by Ca 2+ and Mg 2+ . The groundwater passes through rocks that contain Na-rich minerals, which leads to exchange reactions and increased Na + in groundwater. For deep groundwater, the negative ion exchange process dominates, and accounts for 66.7% of the ion exchange. This process mainly occurs in the edge part of the basin, and is consistent with the shallow groundwater processes. The CAI1 and CAI2 of shallow groundwater ranged from − 6.3 to 0.81 and − 0.24 to 0.76, respectively, while the CAI1 and CAI2 of deep groundwater ranged from − 12.4 to 0.62 and − 0.31 to 0.22, respectively. This suggested that the intensity of the cation exchange is different for the shallow and deep groundwater. The slope and correlation coefficients of the equations for the shallow and deep groundwater (Fig. 8 b) are − 1.88 (R 2 = 0.86) and − 0.34 (R 2 = 0.88), indicating that Ca 2+ , Mg 2+ , and Na + participate in ion exchange. However, significant differences were observed between the theoretical and actual values, implying that cation exchange is not the sole process affecting the concentration of the three ions. The other processes affecting the ion content include the discharge of mine drainage, and the interaction between groundwater and surface water. These processes affect ion content because of the high Na + content of mine drainage and surface water (Table 1 ). To better understand the hydrogeochemical processes in the aquifers, PHREEQC (Parkhurst and Appelo, 1999 ) was used to calculate the saturation indices of the major minerals. The saturation indices of minerals varied between − 0.5 and + 0.5, which indicates that groundwater is saturated (or in equilibrium) or near saturation with respect to these minerals. As shown in Fig. 9 a and b, most of the groundwater samples are in a state of saturation or over-saturation with respect to calcite and dolomite. Almost all the groundwater samples are in a state of under-saturation with respect to gypsum and are highly unsaturated in terms of halite (Fig. 9 c and d). Precipitation is the main source of groundwater in the study area. During the percolation of weakly acidic rain, carbonate minerals dissolve quickly and it is easy for groundwater to reach a dissolution equilibrium with calcite and dolomite. No significant correlation is observed between TDS and the SI values of calcite and dolomite. SI values of gypsum and halite, however, tend to increase with TDS, which indicates that the dissolution of gypsum and halite is one of the main processes involved in the increase in groundwater salinity. 4.4. Effects of anthropogenic activities on hydrochemistry The Changzhi Basin has a long history of agricultural development, and the main crops grown are corn and wheat. Furthermore, the Changzhi Basin is located in southeastern Shanxi Province, near the location of the Jindong coal-based industries. Human activities associated with these socio-economic developments impose extensive impacts on the groundwater environment. These impacts stem from the use of fertilizers in the agricultural areas, water drainage during coal mining, and sewage discharge from urban areas. Groundwater pollution caused by anthropogenic activities is a world-wide issue (Li et al., 2019 ). According to the monitoring results from 195 cities in China, 97% of urban groundwater has been polluted (Zhang, 2015 ). From Table 1 , the following are observed of the NO 3 − concentrations: 22 of the shallow groundwater samples exceed the limits of the level III quality standards for groundwater (20 mg·L − 1 as NO 3 -N), and have a mean value of 55.3 mg·L − 1 . 18 of the shallow groundwater samples exceed the limits of the level IV quality standards for groundwater (30 mg·L − 1 as NO 3 -N) and have a mean value of 65.68 mg·L − 1 . Seven of the deep groundwater samples exceed the limits of the level III quality standards for groundwater and have a mean value of 47.44 mg·L − 1 . Three of the deep groundwater samples exceed the limits of the level IV quality standards for groundwater, and have a mean value of 76.28 mg·L − 1 . Thus, NO 3 -N pollution in the shallow groundwater is more serious than that in the deep groundwater, and mainly occurs in the central and northeastern agricultural areas, and in the urban area in the east of the basin. The main sources of NO 3 -N exceedance are fertilizer application and the discharge of human waste and sewage. The average nitrogen fertilizer application rate per ha of cultivated land is approximately 832.81 kg, which is far in excess of the average rate for China (339 kg/ha) (Chen et al., 2016 ). Mine drainage during coal mining is also a cause for concern because of the relatively high Na + , Cl − , SO 4 2− , HCO 3 − , and TDS concentrations. When compared with the combined average values for shallow groundwater, deep groundwater, and surface water, the mine water has the following characteristics: Mean Na + content of mine drainage was 7.69–23.87 times that of the combined average. Mean Cl - content was 3.36–7.56 times the average. Mean SO 4 2- content was 1.86–2.97 times the average. Mean HCO 3 - content was 2.25–3.29 times the average. Mean TDS content was 2.16–3.15 times the average. The amount of mine drainage was 0.39 million m 3 ·d − 1 in the Changzhi mining area, and was directly discharged into surface water, which interacts with groundwater, especially shallow groundwater, thus leading to an increase in Na + , Cl − , SO 4 2− , and HCO 3 − content of groundwater. 5. Conclusions In this study, the integrated approach consisting of Piper diagram, stable isotopes, Gibbs diagrams and ionic ratios provided an efficient way for analyzing the groundwater origin and hydrochemical processes that affected water chemistry. The Piper diagram and coefficient of variation were used to characterize the groundwater hydrochemistry and the stability of ions content; stable isotopes was a useful tool for analysis the origin and transformation of groundwater; Gibbs diagrams were used to establish the dominant effects of precipitation, rock weathering, or evaporation on geochemical evolution of groundwater, and deuterium excess was a capable way to quantify the contribution of evaporation to groundwater salinity; ionic ratios and saturation indices were used to depict the effects of mineral dissolution or precipitation on groundwater salinity. These methods were complementary of and verify each other. The main conclusions drawn are summarized as follows: The groundwater chemistry type of both shallow and deep groundwater demonstrates zonational characteristics from the west to east of the basin; the TDS content gradually increases (from 208.8 to 2,559 mg·L − 1 ) and the types of hydrochemistry tend to be complex. In both shallow and deep groundwater, the hydrochemistry types are mainly HCO 3 -Ca and HCO 3 ·SO 4 -Ca·Mg. The stable isotope compositions suggest that rain water is main recharge source for both shallow and deep groundwater. The interactions between shallow and deep groundwater, surface water and shallow groundwater and the lateral recharge from fissure groundwater at the edge of the basin have affected the isotopic composition of groundwater. The hydrochemical and isotopic interpretation showed that the hydrochemical composition of the groundwater was controlled by geochemical processes. Gibbs diagrams suggested that water-rock interaction was the main mechanism controlling groundwater chemistry. The deuterium excess method revealed that that mineral dissolution accounts for 81–98% of the salinity of shallow groundwater and 84–98% of deep groundwater. The dissolution of gypsum and halite makes a significant contribution to the increase of groundwater salinity. Overall, rock weathering in conjunction with the cation exchange absolutely predominated in the geochemical evolution of groundwater. The hydrochemical composition of groundwater in the study area is also affected by anthropogenic activities. NO 3 -N pollution occurs in the central area, the northeastern agricultural area, and the urban area in the east of the basin, and is more serious for shallow groundwater than for deep groundwater. The main sources of NO 3 -N are fertilizer application, human waste, and sewage. Mine drainage has relatively high concentrations of Na + , Cl − , SO 4 2− , HCO 3 − , and TDS when compared with shallow groundwater, deep groundwater, and surface water. Mine drainage is directly discharged into surface water and consequently interacts with groundwater, thus leading to an increase of Na + , Cl − , SO 4 2− , and HCO 3 − content of groundwater. The results of the present study provide a deeper insight into the water quality situation and geochemical evolution of groundwater, and will assist decision-makers to formulate sustainable groundwater management strategies for the study area. Declarations Conflicts of interest The authors declare no conflicts of interest. Acknowledgments This work was supported by the Fundamental Research Funds for the Chinese Academy of Geosciences (No. JYYWF20180401) and the China Geological Survey project (No. DD20160296, DD20201123). We thank Paul Seward, PhD, from Liwen Bianji, Edanz Editing China (www.liwenbianji.cn/ac), for editing the English text of a draft of this manuscript. References Appelo C, Postma D (2004) Geochemistry, Groundwater and Pollution Belkhiri L, Boudoukha A, Mouni L et al (2011) Statistical categorization geochemical modeling of groundwater in Ain Azel plain (Algeria). Journal of African Earth Science 59:140–148 Carol E, Mas-Pla J, Kruse E (2013) Interaction between continental and estuarine waters in the wetlands of the northern coastal plain of Samborombón Bay, Argentina. Applied Geochemistry 34:152–163 Chang J, Wang G (2010) Major ions chemistry of groundwater in the arid region of Zhangye Basin, northwestern China. Environmental Earth Science 61:539–548 Chen J, Wu H, Qian H (2016) Groundwater nitrate contamination and associated health risk for the rural communities in an agricultural area of Ningxia, northwest China. Expo Health 8:1–11 Chen J, Liu X, Wang C et al (2012) Isotopic constraints on the origin of groundwater in the Ordos Basin of northern China. Environmental Earth Science 66:505–517 Chen L, Zhang Y, Wang C (2012) A study of evolution of the discharge of the Xin’an spring with time series analysis. Hydrogeology Engineering Geology 39:19–23 (in Chinese) Clark I, Fritz P (1997) Environmental Isotopes in Hydrogeology. Lewis Publishers, New York Cook P, Herczeg A (1999) Environmental traces in subsurface hydrology. Kluwer, Dordrecht Dansgaard W (1964) Stable isotopes in precipitation. Tellus 16:436–468 Farid I, Trabelsi R, Zouari K et al (2013) Hydrogeochemical processes affecting groundwater in an irrigated land in Central Tunisia. Environmental Earth Science 68:1215–1231 Gibbs R (1970) Mechanisms controlling world water chemistry. Science 170:1088–1090 Huang G, Sun J, Zhang Y et al (2013) Impact of anthropogenic and natural processes on the evolution of groundwater chemistry in a rapidly urbanized coastal area, South China. Sci Total Environ 463–464:209–221 Huang T, Pang Z (2012) The role of deuterium excess in determining the water salinisation mechanism: a case study of the arid Tarim River Basin, NW China. Applied Geochemistry 27:2382–2388 Jamshidzadeh Z, Mirbagheri S (2011) Evaluation of groundwater quantity and quality in the Kashan Basin, Central Iran. Desalination 270:23–30 Jia Y, Guo H, Xi B et al (2017) Sources of groundwater salinity and potential impact on arsenic mobility in the western Hetao Basin, Inner Mongolia. Sci Total Environ 601–602:691–702 Li Z, Yang Q, Yang Y et al (2019) Isotopic and geochemical interpretation of groundwater under the influences of anthropogenic activities. Journal of Hydrology 576:685–697 Li Z, Wang G, Wang X et al (2018) Groundwater quality and associated hydrogeochemical processes in Northwest Namibia. Journal of Geochemical Exploration 186:202–214 Liu F, Song X, Yang L et al (2015) The role of anthropogenic and natural factors in shaping the geochemical evolution of groundwater in the Subei Lake basin, Ordos energy base, Northwestern China. Science of the Total Environment 538:327–340 Marfia A, Krishnamurthy R, Atekwana E et al (2004) Isotopic and geochemical evolution of ground and river waters in a karst dominated geological setting: a case study from Belize, Central America. Applied Geochemistry 19:937–946 McDonnell J, Beven K (2014) Debates-The future of hydrological sciences: a (common) path forward? A call to action aimed at understanding velocities, celerities and residence time distributions of the headwater hydrograph. Water Resource Research 50:5342–5350 Mohanty A, Rao V et al (2019) Hydrogeochemical, seawater intrusion and oxygen isotope studies on a coastal region in the Puri District of Odisha, India. Catena 172:558–571 Parkhurst D, Appelo C (1999) User’s guide to PHREEQC – a computer program for speciation, reaction-path, 1D-transport, and inverse geochemical calculation. US Geological Survey Water Resources Investigations Report. 99-4259 Plummer L, Busby J, Lee R et al (1990) Geochemical modeling of the Madison aquifer in parts of Montana, Wyoming, and South Dakota. Water Resour Res 26:1981–2014 Qian H, Li P, Wu J (2013) Isotopic characteristics of precipitation, surface and groundwater in the Yinchuan plain, Northwest China. Environmental Earth Science 70:57–70 Sánchez D, Barberá J, Mudarra M (2015) Hydrogeochemical tools applied to the study of carbonate aquifers: examples from some karst systems of Southern Spain. Environmental Earth Science 74:199–215 Sandow M, Bruce B, Thomas M (2010) Analysis of groundwater quality using multivariate and spatial analyses in the Keta basin, Ghana. Journal of African Earth Sciences 58:220–234 Schoeller H (1967) Geochemistry of Groundwater- an International Guide for Research and Practice Selvakumar S, Chandrasekar N, Kumar G (2017) Hydrogeochemical characteristics and groundwater contamination in the rapid urban development areas of Coimbatore, India. Water Resource Industry 17:26–33 Skrzypek G, Dogramaci S, Grierson P (2013) Geochemical and hydrological processes controlling groundwater salinity of a large inland wetland of northwest Australia. Chemical Geology 357:164–177 Sun X (2008) The application of fuzzy judgement in karst groundwater quality of Xin’an spring region. Journal of Taiyuan University of Technology 39:418–421 (in Chinese) Tizro T, Voudouris K (2008) Groundwater quality in the semi-arid region of the Chahardouly basin, West Iran. Hydrological Processes 22:3066–3078 Wang Y, Guo Q, Su C, Ma T (2006) Strontium isotope characterization and major ion geochemistry of karst water flow, Shentou, northern China. Journal of Hydrology 328:592–603 Xing LN et al (2013) Groundwater hydrochemical characteristics and processes along flow paths in the North China Plain. J Asian Earth Science 70–71:250–264 Yang Q, Li Z, Ma H et al (2016) Identification of the hydrogeochemical processes and assessment of groundwater quality using classic integrated geochemical methods in the Southeastern part of Ordos basin, China. Environmental Pollution 2:879–888 Yang R, Jin H, Hao X et al (2016) Assessment of karst groundwater vulnerability in Xin'an spring area based on modified RISKE model. Environmental Science Technology 39:170–174 (in Chinese) Zang C, Dame J, Nüsser M (2018) Hydrochemical and environmental isotope analysis of groundwater and surface water in a dry mountain region in Northern Chile. Environ Monit Assess 190:334 Zhai Y, Zheng F, Zhao X et al (2019) Identification of hydrochemical genesis and screening of typical groundwater pollutants impacting human health: A case study in Northeast China. Environmental Pollution 252:1202–1215 Zhang C, Wang W, Sun Y et al (2015) Processes of hydrochemical evolution of groundwater in the Guanzhong basin, China. Journal of Groundwater Science Engineering 3:136–146 Zhang H (2015) Risk assessment on Non-point Nitrogen Pollution in groundwater. Jilin University Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 15 Oct, 2021 Reviewers invited by journal 15 Oct, 2021 Editor assigned by journal 17 Aug, 2021 First submitted to journal 17 Aug, 2021 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-823775","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":56903091,"identity":"5517899f-8341-48e7-876a-d6bf7abe2e1e","order_by":0,"name":"Chunchao Zhang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAtElEQVRIiWNgGAWjYBACNgkILcfG3n6ANC3GfDxnEoi0BqolcZ6EgwFxOvikmw+//FFjl94mwZDA8KNiGxEOkzmWZiFxLDm3TbrxAGPPmdtEaJHIMTMwbDiQ2yZzIIGZsY0oLfnfDBIbDqSzSSQYEKslh/nBwYYDCaRoSTNjbDiWbNgGDOSDRPlFfkby44/AEJOXb28/+OBHBRFaGBCxycBwgCj1QMD8gViVo2AUjIJRMEIBALYzODrpq6DoAAAAAElFTkSuQmCC","orcid":"","institution":"Institute of Hydrogeology and Environmental Geology","correspondingAuthor":true,"prefix":"","firstName":"Chunchao","middleName":"","lastName":"Zhang","suffix":""},{"id":56903092,"identity":"9fe2630f-ef49-400a-a30d-5ec2e31ae9f3","order_by":1,"name":"Xiangquan Li","email":"","orcid":"","institution":"Institute of Hydrogeology and Environmental Geology","correspondingAuthor":false,"prefix":"","firstName":"Xiangquan","middleName":"","lastName":"Li","suffix":""},{"id":56903093,"identity":"d08885a2-139b-446d-877a-a3c94ece1c27","order_by":2,"name":"Jianfei Ma","email":"","orcid":"","institution":"Institute of Hydrogeology and Environmental Geology","correspondingAuthor":false,"prefix":"","firstName":"Jianfei","middleName":"","lastName":"Ma","suffix":""},{"id":56903094,"identity":"67219672-df1c-41c1-9104-06c0075fe9be","order_by":3,"name":"Zhenxing Wang","email":"","orcid":"","institution":"Institute of Hydrogeology and Environmental Geology","correspondingAuthor":false,"prefix":"","firstName":"Zhenxing","middleName":"","lastName":"Wang","suffix":""},{"id":56903095,"identity":"d97bece5-036f-4a1c-b817-cb6738a6ee58","order_by":4,"name":"Xinwei Hou","email":"","orcid":"","institution":"Institute of Hydrogeology and Environmental Geology","correspondingAuthor":false,"prefix":"","firstName":"Xinwei","middleName":"","lastName":"Hou","suffix":""}],"badges":[],"createdAt":"2021-08-18 09:13:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-823775/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-823775/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":15094580,"identity":"7163cfd0-24cb-4e41-b33f-0a10cf63c09b","added_by":"auto","created_at":"2021-11-01 15:23:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1299154,"visible":true,"origin":"","legend":"Location of the study area and sampling sites","description":"","filename":"fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/95a33d6c64b6484ac7b44f0f.png"},{"id":15094851,"identity":"470c722d-5dfa-4846-b95e-b4f1799abeab","added_by":"auto","created_at":"2021-11-01 15:26:13","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":680587,"visible":true,"origin":"","legend":"Hydrogeological cross-section (along line A-A’ in Fig. 1) of the study area","description":"","filename":"fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/5b129007951f069f2bc98bde.png"},{"id":15094587,"identity":"a3c6995e-e2bf-413b-bfe0-497b0ea823fc","added_by":"auto","created_at":"2021-11-01 15:23:13","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":552473,"visible":true,"origin":"","legend":"Piper diagrams of: (a) surface water, mine drainage, and rain water; (b) shallow groundwater; and (c) deep groundwater.","description":"","filename":"fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/014ce78eca787121db1cda83.png"},{"id":15094849,"identity":"c781a900-653e-45a6-8625-72ac9509423f","added_by":"auto","created_at":"2021-11-01 15:26:12","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":61309,"visible":true,"origin":"","legend":"Plots of δ18O versus δ2H for all water bodies","description":"","filename":"fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/dac825d5c0edb45714141ddb.png"},{"id":15094585,"identity":"e8ca0857-d201-46af-abf2-585e2b242f5e","added_by":"auto","created_at":"2021-11-01 15:23:13","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":65838,"visible":true,"origin":"","legend":"Gibbs diagrams of groundwater samples from the Changzhi Basin","description":"","filename":"fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/64835574535bbf9251db568c.png"},{"id":15094848,"identity":"b919dec2-945c-4161-b543-2fa91793a5bf","added_by":"auto","created_at":"2021-11-01 15:26:12","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":102167,"visible":true,"origin":"","legend":"Relationship between TDS and (a) deuterium excess, (b) contribution of mineral dissolution, and (c) evaporation in the Changzhi Basin.","description":"","filename":"fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/2ecba8a848badb724b975d24.png"},{"id":15095403,"identity":"898bdbd3-7bb5-4ab4-b3c0-d4b59d635bac","added_by":"auto","created_at":"2021-11-01 15:29:12","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":43877,"visible":true,"origin":"","legend":"Plots of (a) (Ca2++Mg2+) vs. (HCO3- + SO42-), and (b) Na+ vs. Cl- (b) (units are meq·L−1)","description":"","filename":"fig7.png","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/dab4e7bd5d58ec8e74b4803e.png"},{"id":15094588,"identity":"87c1ece2-286a-4c36-a821-8d46a407f3a4","added_by":"auto","created_at":"2021-11-01 15:23:14","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":39262,"visible":true,"origin":"","legend":"CAI1 vs. CAI2 (a) and (Ca2++Mg2+) − (HCO3-+SO42-) vs. (Na++K+−Cl-) (b) of groundwater","description":"","filename":"fig8.png","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/b60b289d395ec9c9637da130.png"},{"id":15094852,"identity":"feb41c33-2416-4539-8832-e69e3cbf6e1c","added_by":"auto","created_at":"2021-11-01 15:26:13","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":135751,"visible":true,"origin":"","legend":"Saturation indices of groundwater samples vs. TDS: (a) calcite, (b) dolomite, (c) gypsum, (d) halite.","description":"","filename":"fig9.png","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/f413708c3ac0210206f1ff92.png"},{"id":15095475,"identity":"23eb72f6-3512-4963-be10-7ebb8622a058","added_by":"auto","created_at":"2021-11-01 15:29:23","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1821624,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-823775/v1/147bed3d-1050-4af5-90f1-9c5b85e5978b.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eStable Isotope and Hydrochemical Evolution of Groundwater in Mining Area of the Changzhi Basin, Northern China\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eGroundwater resources are increasingly exploited for industrial and agricultural purposes in many arid and semi-arid regions globally (Li et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Liu et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). In the last few decades, rapid developments in industry, agriculture, and coal mining, together with rapid urban population growth, has led to dramatic changes in water chemistry in many developing countries (Jamshidzadeh and Mirbagheri, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Sandow et.al, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Water chemistry can be used to facilitate an understanding of the natural geochemical processes and the effects of anthropogenic activities (Liu et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Selvakumar et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). The study of hydrochemical processes and the factors affecting water quality provides an insight to the controlling mechanisms of groundwater hydrochemistry, and is important for sustainable development and effective protection of groundwater (Tizro and Voudouris, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Chang and Wang, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Yang et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Mohanty et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe combination of hydrogeochemical methods such as the Piper diagram, Gibbs diagram, ionic ratios, and multiple isotopic analyses have been widely used to study hydrochemical evolution (Plummer et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1990\u003c/span\u003e; Marfia et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Wang et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Qian et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Liu et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; S\u0026aacute;nchez et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Isotopic and geochemical indicators often serve as effective methods for solving multiple problems in hydrology and hydrogeology, especially in semi-arid and arid regions (Clark and Fritz, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Zang et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Stable isotopes of H and O are typical tracers for investigating the sources of groundwater recharge and the hydrological cycle because the stable isotopes are constituents of the water molecules (Chen et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Jia et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Hydrogeochemical indicators in different water bodies can provide information on the geochemical reactions within the aquifer and on the possible evolutionary pathways of groundwater (Cook and Herczeg, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Appelo and Postma, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2004\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe Changzhi Basin is located in the arid to semi-arid area of northern China. Because of population growth and the increasing development of agricultural and coal mining activities, the demand for groundwater is continually increasing. Groundwater pollution in the Changzhi Basin is, however, increasing as a result of the large-scale and long-term discharge of coal mining water, domestic sewage, and industrial waste water, and the excessive use of fertilizers. Various studies on karst groundwater in the Changzhi Basin have been conducted, and were mainly focused on karst spring flow, groundwater quality, and water resource protection (Sun, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Chen et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Yang et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Studies on groundwater hydrochemistry and evolution processes in the porous media are lacking. The present study addresses this knowledge gap. To obtain a comprehensive understanding of the evolution of groundwater hydrochemistry in the Changzhi Basin, it is necessary to identify the impacts of natural factors and anthropogenic activities on the groundwater hydrochemistry. Consequently, the main objectives of the present study are to: (1) interpret the hydrochemical and stable isotopic characteristics; (2) ascertain the origin of groundwater and reveal the hydrochemical formation mechanisms for both natural geochemical processes and anthropogenic activities; and (3) quantify the contribution of mineral dissolution, evaporation, and cation exchange factors in controlling the chemical composition of groundwater.\u003c/p\u003e"},{"header":"2. Regional Hydrogeology","content":"\u003cp\u003eThe Changzhi Basin is located in the southeast of Shanxi Province (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), encompassing an area of 1,169 km\u003csup\u003e2\u003c/sup\u003e, and lying between 36\u0026deg;00\u0026prime; and 36\u0026deg;19\u0026prime; N and 112\u0026deg;46\u0026prime; and 113\u0026deg;16\u0026prime; E. The annual mean air temperature of the study area ranged from 8.9 to 10.9\u0026deg;C over the past 30 years. The average rainfall from 1956 to 2018 was 536 mm, with a range from 264 mm (1965) to 1,056 mm (1971). 60\u0026ndash;70% of the annual rainfall was concentrated in July, August, and September. The annual mean water surface evaporation was 1,678 mm, with a maximum of 1,810 mm and a minimum of 1,372 mm. The Zhuozhang River, the main river in the basin, runs from the south to the north. The main tributaries of the Zhuozhang River are the Taoqing, Lanshui, Jianghe, and Yuni Rivers. The Zhangze Reservoir is the only large-scale reservoir in the study area, while there are many medium and small-sized reservoirs, such as the Baojiahe, Tunjiang, and Shencun Reservoirs.\u003c/p\u003e \u003cp\u003eGeologically, Changzhi Basin is a Cenozoic fault basin. The main outcropping strata in the study area are of Quaternary (Q) age. Permian (P), Carboniferous (C), and Ordovician (O) strata outcrop locally. The Quaternary sediments are 0\u0026ndash;300 m thick, and the sediments thicken from west to east (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The main aquifers are in the unconsolidated sediments, and divided into shallow (\u0026le;\u0026thinsp;50 m in depth) and deep (\u0026gt;\u0026thinsp;50 m in depth) aquifers. The shallow aquifer is unconfined in alluvial-proluvial sand-gravel layers of the Holocene and Upper Pleistocene. The deep aquifer is confined in silt, sand, and gravel lenses of the Middle and Lower Pleistocene. The unconfined and confined aquifers are separated by a discontinuous aquitard composed of a mudstone layer. The regional groundwater flows towards the Zhangze Reservoir and Zhuozhang River (i.e., from the west, east, and south).\u003c/p\u003e"},{"header":"3. Sampling And Analysis","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Sample collection\u003c/h2\u003e \u003cp\u003eA total of 117 groundwater samples were collected in April and November, 2018. The samples comprised 76 shallow groundwater samples, 36 deep groundwater samples, and 5 mine drainage samples. The sampling locations are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Mine drainage samples were taken from the water drained from the mines to enable the exploitation of coal-bed methane and coal. Additionally, 24 rainwater samples were collected from central, eastern, and western areas of the basin from July, 2017 to July, 2018 for stable isotope tests; whereas, three of these samples were also used for hydrochemical tests. The samples were filtered through 0.45 \u0026micro;m membranes on site and then stored at 4\u0026deg;C. The bottles were rinsed twice with deionized water before sampling. For cation analysis, water samples were acidified using analytically pure nitric acid to pH\u0026thinsp;\u0026lt;\u0026thinsp;2. Samples for stable isotope analysis (δ\u003csup\u003e18\u003c/sup\u003eO and δ\u003csup\u003e2\u003c/sup\u003eH) were collected in 50 mL glass bottles, which were sealed with airtight caps.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Measurement methods\u003c/h2\u003e \u003cp\u003eWater temperature, pH, and electrical conductivity were directly measured on-site using a HANNA HI 991301 multi-parameter instrument. Major anions, cations and minor elements were analyzed by a Thermo Scientific Dionex ICS-4000 (precision\u0026thinsp;=\u0026thinsp;\u0026plusmn;\u0026thinsp;1%) and PerkinElmer Optima 8300 inductively coupled plasma-optical emission spectrometer (precision\u0026thinsp;=\u0026thinsp;\u0026plusmn;\u0026thinsp;1%) at the Groundwater Mineral Water and Environmental Monitoring Center in the Institute of Hydrogeology and Environmental Geology at the Chinese Academy of Geological Sciences. The analytical precision and electrical balance error of the hydrochemical data were within \u0026plusmn;\u0026thinsp;5%.\u003c/p\u003e \u003cp\u003eStable isotope ratios were expressed in δ (\u0026permil;) notation and calculated with respect to Vienna Standard Mean Ocean Water (VSMOW). The δ\u003csup\u003e18\u003c/sup\u003eO and δD values in water samples were obtained using a Picarro L2130-i Analyzer at the Institute of Hydrogeology and Environmental Geology at the Chinese Academy of Geological Sciences. The analytical precision for δD was \u0026plusmn;\u0026thinsp;1\u0026permil; and for δ\u003csup\u003e18\u003c/sup\u003eO was \u0026plusmn;\u0026thinsp;0.1\u0026permil;.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Results And Discussion","content":"\u003cdiv class=\"Section2\" id=\"Sec7\"\u003e\n \u003ch2\u003e4.1. Hydrochemical characteristics\u003c/h2\u003e\n \u003cp\u003eThe physicochemical parameters of the water samples are shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e; all water sample data were plotted on Piper diagrams (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea\u0026ndash;c). A coefficient of variation (Cv) is commonly used to characterize the stability of a variable: 0\u0026thinsp;\u0026lt;\u0026thinsp;Cv\u0026thinsp;\u0026lt;\u0026thinsp;0.1 indicates weak variability; 0.1\u0026thinsp;\u0026lt;\u0026thinsp;Cv\u0026thinsp;\u0026lt;\u0026thinsp;1.0 indicates moderate variability; and Cv\u0026thinsp;\u0026gt;\u0026thinsp;1.0 indicates wide variability (Yang et al., \u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e; Zhai et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"Section3\" id=\"Sec8\"\u003e\n \u003ch2\u003e4.1.1. Rain water, surface water, and mine drainage\u003c/h2\u003e\n \u003cp\u003eThe pH values of rain water ranged from 6.39 to 6.63, indicating weakly acidic conditions. Surface water (pH 7.03\u0026ndash;7.94) and mine drainage (pH 7.85\u0026ndash;8.90) were generally neutral to weakly alkaline. The concentrations of the chemical components in rain water were, in general, low. Most of the chemical components in surface water and rain water exhibited a weak to medium variability, but a wide variability in mine drainage. The maximum concentrations of total dissolved solids (TDS), Na\u003csup\u003e+\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, and SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e for mine drainage were 2,901, 1,176, 1,078, and 1,218 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively, and were significantly greater than the maximum concentrations for surface water and rain water.\u003c/p\u003e\n \u003cp\u003eThe chemical components of surface water were dominated by Ca\u003csup\u003e2+\u003c/sup\u003e, Na\u003csup\u003e+\u003c/sup\u003e, HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, and Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, and the hydrochemical types were complex. The HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca\u0026middot;Mg, HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;Cl\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca\u0026middot;Na, HCO\u003csub\u003e3\u003c/sub\u003e-Ca\u0026middot;Na, SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;Cl-Na\u0026middot;Ca, and HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;Cl-Ca types were all identified for surface water. The chemical components of mine drainage were dominated by Na\u003csup\u003e+\u003c/sup\u003e, HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, and Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, and hydrochemical types were mainly HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;Cl-Na and SO\u003csub\u003e4\u003c/sub\u003e-Na. The chemical components of rain water were, however, dominated by Ca\u003csup\u003e2+\u003c/sup\u003e, HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, and SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, and the hydrochemical type was HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec9\"\u003e\n \u003ch2\u003e4.1.2. Groundwater\u003c/h2\u003e\n \u003cp\u003eThe pH values of the shallow groundwater ranged from 7.13 to 8.07, and had a mean value of 7.53, which indicates near neutral to weakly alkaline conditions. Total hardness (TH) and TDS of the shallow groundwater varied from 168.1 to 1,889 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and from 208.8 to 2,559 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. The chemical components were dominated by Ca\u003csup\u003e2+\u003c/sup\u003e, HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, and Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e. Of the shallow groundwater samples, 51% were of the HCO\u003csub\u003e3\u003c/sub\u003e-Ca type and had a low TDS (mean value\u0026thinsp;=\u0026thinsp;409.6 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e); 16% were of the HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca/Mg type and had a medium TDS (mean value\u0026thinsp;=\u0026thinsp;647.6 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e); and 13% were of the SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;HCO\u003csub\u003e3\u003c/sub\u003e(SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;Cl)-Ca/Mg type and had a high ion content (mean value\u0026thinsp;=\u0026thinsp;1,412.5 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). Moreover, the SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;Cl-Ca, Cl\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca, and HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;Cl-Ca type was also identified for shallow groundwater (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb). The Cv values of K\u003csup\u003e+\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, and NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e were greater than 1.0, which indicates that these hydrochemical components had a wide variation in spatial distribution. The TDS content gradually increased (from 208.8 to 2,559 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) from the west to the east of the basin. In the west of the basin, the chemical type was mainly HCO\u003csub\u003e3\u003c/sub\u003e-Ca. However, in the east of the basin, the chemical types were complex: SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;HCO\u003csub\u003e3\u003c/sub\u003e-Ca/Mg, SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;Cl-Ca, Cl\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca, and HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;Cl-Ca were all identified and the TDS values were high (780\u0026ndash;2,559 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e).\u003c/p\u003e\n \u003cp\u003eFor deep groundwater, the pH values ranged from 7.04 to 7.97, with a mean value of 7.57, indicating near neutral to weakly alkaline conditions. The TH and TDS of the deep groundwater varied from 177.1 to 1,559 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and from 240.2 to 2,160 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. The chemical components were dominated by Ca\u003csup\u003e2+\u003c/sup\u003e, Mg\u003csup\u003e2+\u003c/sup\u003e, HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, and SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e. Of the deep groundwater samples, 61% were of the HCO\u003csub\u003e3\u003c/sub\u003e-Ca/Mg type and had a low TDS (mean values\u0026thinsp;=\u0026thinsp;381.8 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e); 17% were of the HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca/Mg type and had a medium TDS (mean values\u0026thinsp;=\u0026thinsp;653.45 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e); and 8% were of the SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;HCO\u003csub\u003e3\u003c/sub\u003e-Ca/Mg type and had a high ion content (mean values\u0026thinsp;=\u0026thinsp;1,277.4 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). Moreover, the HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;Cl-Ca and HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;Cl\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca types were also identified (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ec). The Cv values of Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, and NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e were greater than 1.0, indicating that these hydrochemical components had a wide variation in spatial distribution. The TDS of the deep groundwater gradually increased (from 240.2 to 2,160 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) from the west to the east of the basin. In the west and central of the basin, the groundwater is mainly of the HCO\u003csub\u003e3\u003c/sub\u003e-Ca type. However, in the east of the basin, as a result of low discharge and weak self-purification capacity, the SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;HCO\u003csub\u003e3\u003c/sub\u003e-Ca/Mg, HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e\u0026middot;Cl-Ca, and HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;Cl\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca types were all identified for the deep groundwater, which had a high TDS of approximately 800\u0026ndash;2,160 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eThe concentrations of minor and trace elements, such as F, Cr, As, Fe, Mn, and Pb, were generally low, and most were not detected. In terms of the Groundwater Quality Standards of China (GB/T 14848\u0026thinsp;\u0026minus;\u0026thinsp;2017), values of F, Cr, and As are all below the Chinese III quality standards (1.0 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for F, 0.05 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Cr, and 0.01 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for As). The concentrations of Fe, Mn, and Pb exceed the III quality standards in some samples. The standards for Fe, Mn, and Pb (0.3 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Fe, 0.10 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Mn, and 0.01 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Pb) were exceeded in samples 6, 7, and 6, respectively. These samples were taken from shallow groundwater.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u003ctable border=\"1\" id=\"Tab1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eChemical properties and composition of groundwater, surface water, rain water, and mine drainage samples in the Changzhi Basin. n\u0026thinsp;=\u0026thinsp;number of samples; Cv\u0026thinsp;=\u0026thinsp;coefficient of variation; TH\u0026thinsp;=\u0026thinsp;total hardness; TDS\u0026thinsp;=\u0026thinsp;total dissolved solids. Units: pH in units of pH, major ions and minor elements in mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003eshallow groundwater(n\u0026thinsp;=\u0026thinsp;76)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\" style=\"width: 17.6471%;\"\u003e\n \u003cp\u003edeep groundwater(n\u0026thinsp;=\u0026thinsp;37)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 1.023%;\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003esurface water(n\u0026thinsp;=\u0026thinsp;11)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003erain water(n\u0026thinsp;=\u0026thinsp;3)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003emine drainage(n\u0026thinsp;=\u0026thinsp;5)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003erange\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eaverage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCv\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003erange\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eaverage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003eCv\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003erange\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAverage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCv\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003erange\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eaverage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCv\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003erange\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eaverage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCv\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003epH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.13\u0026thinsp;~\u0026thinsp;8.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.04\u0026thinsp;~\u0026thinsp;7.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.03\u0026thinsp;~\u0026thinsp;7.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.39\u0026thinsp;~\u0026thinsp;6.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.85\u0026thinsp;~\u0026thinsp;8.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHardness\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e168.1\u0026thinsp;~\u0026thinsp;1889\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e547.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e177.1\u0026thinsp;~\u0026thinsp;1559\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e386.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e0.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e136.1\u0026thinsp;~\u0026thinsp;417.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e267.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.01\u0026thinsp;~\u0026thinsp;19.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.01\u0026thinsp;~\u0026thinsp;360.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e98.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.48\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTDS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e208.8\u0026thinsp;~\u0026thinsp;2559\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e744.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e240.2\u0026thinsp;~\u0026thinsp;2160\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e510.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e0.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e190.1\u0026thinsp;~\u0026thinsp;955\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e511.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.51\u0026thinsp;~\u0026thinsp;48.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e715\u0026thinsp;~\u0026thinsp;2901\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1607.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eK\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.06\u0026thinsp;~\u0026thinsp;30.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.14\u0026thinsp;~\u0026thinsp;2.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e0.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.6\u0026thinsp;~\u0026thinsp;17.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.24\u0026thinsp;~\u0026thinsp;0.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.63\u0026thinsp;~\u0026thinsp;22.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNa\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.08\u0026thinsp;~\u0026thinsp;165.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e36.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.9\u0026thinsp;~\u0026thinsp;73.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e0.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.2\u0026thinsp;~\u0026thinsp;226.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e76.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.39\u0026thinsp;~\u0026thinsp;1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e265.3\u0026thinsp;~\u0026thinsp;1176\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e587.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCa\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e56.06\u0026thinsp;~\u0026thinsp;537.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e159.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50.66\u0026thinsp;~\u0026thinsp;476.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e113.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e0.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.56\u0026thinsp;~\u0026thinsp;115.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e67.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.24\u0026thinsp;~\u0026thinsp;6.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.97\u0026thinsp;~\u0026thinsp;73.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMg\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.78\u0026thinsp;~\u0026thinsp;151.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e36.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.83\u0026thinsp;~\u0026thinsp;89.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e0.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.78\u0026thinsp;~\u0026thinsp;40.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.24\u0026thinsp;~\u0026thinsp;0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.98\u0026thinsp;~\u0026thinsp;42.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCl\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.72\u0026thinsp;~\u0026thinsp;548\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e90.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.26\u0026thinsp;~\u0026thinsp;311\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.51\u0026thinsp;~\u0026thinsp;196.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e80.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.40\u0026thinsp;~\u0026thinsp;2.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e76.42\u0026thinsp;~\u0026thinsp;1078\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e303.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.38\u0026thinsp;~\u0026thinsp;720.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e144.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.61\u0026thinsp;~\u0026thinsp;469.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e90.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e1.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e48.84\u0026thinsp;~\u0026thinsp;314.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e127.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.27\u0026thinsp;~\u0026thinsp;11.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.17\u0026thinsp;~\u0026thinsp;1218\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e269.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.97\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e157.1\u0026thinsp;~\u0026thinsp;581.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e305.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e197.3\u0026thinsp;~\u0026thinsp;482.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e272.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e94.07\u0026thinsp;~\u0026thinsp;290\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e209.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.72\u0026thinsp;~\u0026thinsp;24.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e363.7\u0026thinsp;~\u0026thinsp;941.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e689.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.84\u0026thinsp;~\u0026thinsp;873.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e102.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.39\u0026thinsp;~\u0026thinsp;580.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e61.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e1.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.2\u0026thinsp;~\u0026thinsp;86.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.61\u0026thinsp;~\u0026thinsp;6.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.9\u0026thinsp;~\u0026thinsp;6.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eF\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.29\u0026thinsp;~\u0026thinsp;0.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.23\u0026thinsp;~\u0026thinsp;0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.31\u0026thinsp;~\u0026thinsp;2.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.21\u0026thinsp;~\u0026thinsp;0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.86\u0026thinsp;~\u0026thinsp;7.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.54\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCr\u003csup\u003e6+\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.004\u0026thinsp;~\u0026thinsp;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.004\u0026thinsp;~\u0026thinsp;0.028\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.037\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.032\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.01\u0026thinsp;~\u0026thinsp;0.058\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.01\u0026thinsp;~\u0026thinsp;1.497\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.01\u0026thinsp;~\u0026thinsp;0.599\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.01\u0026thinsp;~\u0026thinsp;0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;2.331\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.134\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.293\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.269\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 3.9643%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 1.0229%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.058\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003c0.001\u0026thinsp;~\u0026thinsp;0.008\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003ctable border=\"1\" id=\"Tab2\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eIsotopic composition of water samples taken in the Changzhi Basin.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003eshallow groundwater\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003edeep groundwater\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003esurface water\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003erain water\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003emine drainage\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMax\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMax\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMax\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMax\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMax\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026delta;\u003csup\u003e2\u003c/sup\u003eH(\u0026permil;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-104\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026delta;\u003csup\u003e18\u003c/sup\u003eO(\u0026permil;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-10.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-6.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-8.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-9.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-9.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-8.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-5.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-6.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-14.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-2.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-6.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-11.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-7.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-9.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec10\"\u003e\n \u003ch2\u003e4.2. \u0026delta;\u003csup\u003e18\u003c/sup\u003eO and \u0026delta;\u003csup\u003e2\u003c/sup\u003eH characteristics and groundwater provenance\u003c/h2\u003e\n \u003cp\u003eStable water isotopes of hydrogen (\u0026delta;\u003csup\u003e2\u003c/sup\u003eH) and oxygen (\u0026delta;\u003csup\u003e18\u003c/sup\u003eO) are increasingly being applied as a useful tool for integrating information about hydrological processes across various scales (McDonnell and Beven, \u003cspan class=\"CitationRef\"\u003e2014\u003c/span\u003e; Li et al, \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e summarizes the isotopic composition of water samples taken in the Changzhi Basin.\u003c/p\u003e\n \u003cdiv class=\"Section3\" id=\"Sec11\"\u003e\n \u003ch2\u003e4.2.1. Rain water, surface water, and mine drainage\u003c/h2\u003e\n \u003cp\u003eThe \u0026delta;\u003csup\u003e18\u003c/sup\u003eO and \u0026delta;\u003csup\u003e2\u003c/sup\u003eH of rain water, surface water, and mine drainage are plotted in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea. The slope of the local meteoric water line (LMWL, k\u0026thinsp;=\u0026thinsp;8.12) is similar to the global meteoric water line (GMWL, k\u0026thinsp;=\u0026thinsp;8.0), and that the compositions of the stable hydrogen and oxygen isotopes are also aligned with the GMWL. The \u0026delta;\u003csup\u003e18\u003c/sup\u003eO and \u0026delta;\u003csup\u003e2\u003c/sup\u003eH compositions of rain water range from \u0026minus;\u0026thinsp;14.1\u0026permil; to \u0026minus;\u0026thinsp;2.0\u0026permil; and \u0026minus;\u0026thinsp;104\u0026permil; to \u0026minus;\u0026thinsp;11\u0026permil;, respectively, surface water ranges from \u0026minus;\u0026thinsp;8.3\u0026permil; to \u0026minus;\u0026thinsp;5.2\u0026permil; and \u0026minus;\u0026thinsp;63\u0026permil; to \u0026minus;\u0026thinsp;46\u0026permil;, respectively, while mine drainage samples range from \u0026minus;\u0026thinsp;11.4\u0026permil; to \u0026minus;\u0026thinsp;7.9\u0026permil; and \u0026minus;\u0026thinsp;84\u0026permil; to \u0026minus;\u0026thinsp;59\u0026permil;, respectively (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eThe surface water and mine drainage samples lie below the LMWL. When compared with the LMWL, the surface water and mine drainage isotopes can be seen to be enriched in heavy isotopes, and are located near the LMWL. This indicates that the surface water and mine drainage are recharged by rain water and have undergone evaporation and condensation, especially in the case of surface water. The mine drainage samples are scattered in the study area and thus could represent different recharge sources (Qian et al., \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec12\"\u003e\n \u003ch2\u003e4.2.2. Groundwater\u003c/h2\u003e\n \u003cp\u003eThe \u0026delta;\u003csup\u003e18\u003c/sup\u003eO and \u0026delta;\u003csup\u003e2\u003c/sup\u003eH of groundwater are plotted in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eb. The \u0026delta;\u003csup\u003e18\u003c/sup\u003eO and \u0026delta;\u003csup\u003e2\u003c/sup\u003eH compositions of groundwater are located near the LMWL, which indicates that the groundwater is mainly recharged by rain water. The slope of the shallow groundwater line (k\u0026thinsp;=\u0026thinsp;6.19) is smaller than that of the deep groundwater line (k\u0026thinsp;=\u0026thinsp;6.41), which means that the groundwater has undergone evaporation during the recharge process, especially in the case of shallow groundwater.\u003c/p\u003e\n \u003cp\u003eThe \u0026delta;\u003csup\u003e18\u003c/sup\u003eO and \u0026delta;\u003csup\u003e2\u003c/sup\u003eH values for shallow groundwater range from \u0026minus;\u0026thinsp;10.1\u0026permil; to \u0026minus;\u0026thinsp;6.3\u0026permil; and \u0026minus;\u0026thinsp;76\u0026permil; to \u0026minus;\u0026thinsp;51\u0026permil;, respectively, while for deep groundwater the corresponding values are \u0026minus;\u0026thinsp;9.9\u0026permil; to \u0026minus;\u0026thinsp;6.5\u0026permil; and \u0026minus;\u0026thinsp;74\u0026permil; to \u0026minus;\u0026thinsp;53\u0026permil;, respectively. Some shallow groundwater samples have relatively low stable isotope concentrations and some deep groundwater samples have relatively high concentrations. This may have resulted from the interaction between shallow and deep groundwater. The \u0026delta;\u003csup\u003e18\u003c/sup\u003eO and \u0026delta;\u003csup\u003e2\u003c/sup\u003eH values of some shallow groundwater samples are consistent with surface water, indicating an interaction between surface water and shallow groundwater. Because of the lateral recharge from fissure groundwater at the edge of the basin, the \u0026delta;\u003csup\u003e18\u003c/sup\u003eO and \u0026delta;\u003csup\u003e2\u003c/sup\u003eH compositions of shallow groundwater are relatively low.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec13\"\u003e\n \u003ch2\u003e4.3. Hydrochemical evolution processes\u003c/h2\u003e\n \u003cdiv class=\"Section3\" id=\"Sec14\"\u003e\n \u003ch2\u003e4.3.1. Effects of precipitation, evaporation, and rock-type on hydrochemistry\u003c/h2\u003e\n \u003cp\u003eA qualitative analysis, using the Gibbs diagram (Gibbs, \u003cspan class=\"CitationRef\"\u003e1970\u003c/span\u003e), was carried out to identify the dominant processes affecting evolution. The Gibbs diagram depicts the relative dominance of precipitation, rock weathering, and evaporation in semi-arid and arid regions. The diagrams show the weight ratios of Na\u003csup\u003e+\u003c/sup\u003e/(Na\u003csup\u003e+\u003c/sup\u003e+Ca\u003csup\u003e2+\u003c/sup\u003e) and Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e/(Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e+HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e) against TDS, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eb shows that the ratios of Na\u003csup\u003e+\u003c/sup\u003e/(Na\u003csup\u003e+\u003c/sup\u003e+Ca\u003csup\u003e2+\u003c/sup\u003e) are mostly less than 0.5 and that the TDS is mostly low to medium, which indicates that rock weathering is the dominant mechanism in the geochemical evolution of groundwater for both shallow and deep groundwater. The ratios of Na\u003csup\u003e+\u003c/sup\u003e/(Na\u003csup\u003e+\u003c/sup\u003e+Ca\u003csup\u003e2+\u003c/sup\u003e), however, show a wide range of values without any obvious changes in TDS values. This suggests that cation exchange also plays an important role by increasing Na\u003csup\u003e+\u003c/sup\u003e and decreasing Ca\u003csup\u003e2+\u003c/sup\u003e when geochemical evolution is dominated by rock-weathering processes (Liu et al., \u003cspan class=\"CitationRef\"\u003e2015\u003c/span\u003e; Li et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). This occurs because 2 mmol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of Na\u003csup\u003e+\u003c/sup\u003e is exchanged with 1mmol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of Ca\u003csup\u003e2+\u003c/sup\u003e during the cation exchange, and the mass concentration of 2 mmol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of Na\u003csup\u003e+\u003c/sup\u003e (46 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) is nearly equal to 1mmol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of Ca\u003csup\u003e2+\u003c/sup\u003e (40 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). Some samples of shallow groundwater, however, are located on the upper right of the Gibbs diagram (Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea), and the ratios of Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e/(Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e+HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e) are greater than 0.5 and the TDS value greater than 1,100 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. This shows that the groundwater chemistry is controlled not only by rock weathering, but also by evaporation (Xing et al., \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec15\"\u003e\n \u003ch2\u003e4.3.2. Effects of evaporation on groundwater salinity based on stable isotope\u003c/h2\u003e\n \u003cp\u003eThe deuterium excess, as one of the most important indicators characterizing atmospheric precipitation for comprehensive environmental factors, is capable of quantifying the contribution of evaporation to groundwater salinity (Dansgaard, \u003cspan class=\"CitationRef\"\u003e1964\u003c/span\u003e; Li et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e; Huang and Pang, \u003cspan class=\"CitationRef\"\u003e2012\u003c/span\u003e). In the study area, \u0026delta;\u003csup\u003e2\u003c/sup\u003eH\u003csub\u003e0\u003c/sub\u003e and \u0026delta;\u003csup\u003e18\u003c/sup\u003eO\u003csub\u003e0\u003c/sub\u003e were calculated for \u0026minus;\u0026thinsp;45\u0026permil; and \u0026minus;\u0026thinsp;6.9\u0026permil; of local mean rain water, although the \u0026delta;\u003csup\u003e2\u003c/sup\u003eH\u003csub\u003e0\u003c/sub\u003e and \u0026delta;\u003csup\u003e18\u003c/sup\u003eO\u003csub\u003e0\u003c/sub\u003e values do not affect the mineral dissolution to total salinity relationship; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({S}_{0}\\)\u003c/span\u003e\u003c/span\u003e, the total salinity of mean rain water, was defined as 0.035 g\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003cem\u003ef\u003c/em\u003e is the remaining fraction of the reservoir; the average temperature of the groundwater was 14\u0026deg;C and the humidity was about 60%. Thus, the relationship between \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(d\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(f\\)\u003c/span\u003e\u003c/span\u003e can be established as given in Eq.\u0026nbsp;(1) (Huang and Pang, \u003cspan class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"Equation\" id=\"Equa\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e$$d=\\delta {}^{2}H-8\\delta {}^{18}O=\\left({\\delta }^{2}{H}_{0}+1000\\right){f}^{({\\alpha }^{2}{H}_{0}-1)}-8\\left({\\delta }^{18}{O}_{0}+1000\\right){f}^{\\left({\\alpha }^{18}{O}_{0}-1\\right)}+7000$$\u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Equation\" id=\"Equb\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e$$=955\\times {f}^{-0.08676}-8\\times 993.1\\times {f}^{-0.01546}+7000 \\left(1\\right)$$\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u0026nbsp;\u003cspan class=\"mathinline\"\u003e\\(\\frac{{S}_{0}}{f}-{S}_{0}\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003e was the salinity caused by direct evaporation; D was the salinity increased by mineral dissolution, and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(D=S-{S}_{0}-(\\frac{{S}_{0}}{f}-{S}_{0})\\)\u003c/span\u003e\u003c/span\u003e (Huang and Pang, \u003cspan class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eAs shown in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea, the average total \u003cem\u003ed-excess\u003c/em\u003e and TDS for shallow groundwater and deep groundwater are 4.63\u0026permil; and 744.02 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 4.72\u0026permil; and 510.86 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. The contribution ratios of mineral dissolution in shallow groundwater and deep groundwater are 81\u0026ndash;98% and 84\u0026ndash;98%, while the contribution ratio of evaporation is 0.2\u0026ndash;4.7% and 0\u0026ndash;2.4%. In the study area, most groundwater depths are greater than 5 m, and the groundwater is mainly recharged by rain water and bedrock fissure water, which favors the dissolution of minerals. Most of the water samples indicate no evaporation effects regardless of shallow groundwater or deep groundwater. Figure \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eb and \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ec show that there is an almost exponential positive correlation between TDS and the contribution of mineral dissolution, and an almost exponential negative correlation between TDS and the contribution of evaporation, which indicates that mineral dissolution is the main contributor to the total salinity of groundwater.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec16\"\u003e\n \u003ch2\u003e4.3.3. Effects of geochemical processes on hydrochemistry\u003c/h2\u003e\n \u003cp\u003eThe relationship between (Ca\u003csup\u003e2+\u003c/sup\u003e + Mg\u003csup\u003e2+\u003c/sup\u003e) and (HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e + SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e) concentrations in groundwater samples is close to the carbonate and gypsum dissolution line (1:1 relationship line) if these ions are controlled by carbonate and gypsum equilibrium (Wang et al., \u003cspan class=\"CitationRef\"\u003e2006\u003c/span\u003e; Zhang et al., \u003cspan class=\"CitationRef\"\u003e2015\u003c/span\u003e). Ion exchange (Ca\u003csup\u003e2+\u003c/sup\u003e and Mg\u003csup\u003e2+\u003c/sup\u003e in groundwater changed by Na\u003csup\u003e+\u003c/sup\u003e) tends to shift points to the right in equilibrium plots as a result of an excess of (HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e + SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e) (Belkhiri et al., \u003cspan class=\"CitationRef\"\u003e2011\u003c/span\u003e; Liu et al., \u003cspan class=\"CitationRef\"\u003e2015\u003c/span\u003e), but reverse ion exchange shifts the points to the left as a result of an excess of (Ca\u003csup\u003e2+\u003c/sup\u003e+Mg\u003csup\u003e2+\u003c/sup\u003e). As shown in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ea, values for most of the deep groundwater samples plot near the 1:1 line, which indicates that the dissolution of carbonate and gypsum is the main geochemical process in deep groundwater. Values for most of shallow groundwater samples are, however, scattered and located above the 1:1 line. This suggests that ion exchange is one of the main geochemical processes occurring in shallow groundwater in addition to the dissolution of carbonate and gypsum.\u003c/p\u003e\n \u003cp\u003eAs shown in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eb, in the shallow groundwater, the Na\u003csup\u003e+\u003c/sup\u003e/Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e mole ratio varies from 0.37 to 13.27, with an average value of 2.07. In the deep groundwater, the ratio ranges from 0.18 to 7.24, with an average value of 1.21. Most of the values for the deep groundwater samples are located near the 1:1 line, which suggests that the dissolution of halite is the major source of Na\u003csup\u003e+\u003c/sup\u003e and Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e for deep groundwater. In contrast, most of the shallow groundwater values are scattered and are located below the 1:1 line. This indicates that there are other geochemical processes than halite dissolution leading to an excess of Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, such as Ca(Mg)/Na ion exchange.\u003c/p\u003e\n \u003cp\u003eIon exchange and adsorption are common reactions in the geochemical evolution of groundwater and influence the major ion composition of groundwater (Li et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). Schoeller (\u003cspan class=\"CitationRef\"\u003e1967\u003c/span\u003e) proposed the chloral-alkali index (CAI) to analyze cation exchange and adsorption (Eqs.\u0026nbsp;(2) and (3)).\u003c/p\u003e\n \u003cdiv class=\"Equation\" id=\"Equc\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e$$CAI1=\\frac{{Cl}^{-}-({Na}^{+}+{K}^{+})}{{Cl}^{-}} \\left(2\\right)$$\u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Equation\" id=\"Equd\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equd\" name=\"EquationSource\"\u003e$$CAI2=\\frac{{Cl}^{-}-({Na}^{+}+{K}^{+})}{{SO}_{4}^{2-}+{HCO}_{3}^{-}+{CO}_{3}^{2-}+{NO}_{3}^{-}} \\left(3\\right)$$\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003eA positive CAI indicates the exchange of Ca\u003csup\u003e2+\u003c/sup\u003e and Mg\u003csup\u003e2+\u003c/sup\u003e from the rocks with Na\u003csup\u003e+\u003c/sup\u003e of the water, while a negative CAI indicates the exchange of Na\u003csup\u003e+\u003c/sup\u003e from the rocks with Ca\u003csup\u003e2+\u003c/sup\u003e and Mg\u003csup\u003e2+\u003c/sup\u003e of the water. Additionally, a diagram of [(Ca\u003csup\u003e2+\u003c/sup\u003e+Mg\u003csup\u003e2+\u003c/sup\u003e) \u0026minus; (HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e+SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e)] versus (Na\u003csup\u003e+\u003c/sup\u003e\u0026minus;Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e) (Eq. (4)) is also commonly used to explain cation exchange in groundwater (Carol et al., \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e; Huang et al., \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e; Liu et al., \u003cspan class=\"CitationRef\"\u003e2015\u003c/span\u003e). The diagram reflects excess Ca\u003csup\u003e2+\u003c/sup\u003e and Mg\u003csup\u003e2+\u003c/sup\u003e gained or lost from calcite, dolomite, and gypsum dissolution or precipitation, and excess Na\u003csup\u003e+\u003c/sup\u003e gained or lost from NaCl (Farid et al., \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e). If cation exchange plays a major role in controlling the major ion composition of groundwater, there will be a linear relationship with a slope close to \u0026minus;\u0026thinsp;1.0, as expressed by Eq.\u0026nbsp;(4).\u003c/p\u003e\n \u003cdiv class=\"Equation\" id=\"Eque\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Eque\" name=\"EquationSource\"\u003e$$N=\\frac{\\left({Na}^{+}+{K}^{+}\\right)-{Cl}^{-}}{{Ca}^{2+}+{Mg}^{2+}-{(HCO}_{3}^{-}+{SO}_{4}^{2-})} \\left(4\\right)$$\u003c/div\u003e\u003c/div\u003e\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003ea shows that both positive and negative ion exchange occurs in groundwater. For shallow groundwater, the positive ion exchange was slightly dominant, and accounted for 51.3% of the ion exchange. This process mainly occurred at the central of the Changzhi Basin, which have a slower runoff and more shallow groundwater compared with the edge of the basin, leads to the large Na\u003csup\u003e+\u003c/sup\u003e content in the water displaced part of Ca\u003csup\u003e2+\u003c/sup\u003e in the aquifer. In the edge part of the basin, the cations in the groundwater are dominated by Ca\u003csup\u003e2+\u003c/sup\u003e and Mg\u003csup\u003e2+\u003c/sup\u003e. The groundwater passes through rocks that contain Na-rich minerals, which leads to exchange reactions and increased Na\u003csup\u003e+\u003c/sup\u003e in groundwater. For deep groundwater, the negative ion exchange process dominates, and accounts for 66.7% of the ion exchange. This process mainly occurs in the edge part of the basin, and is consistent with the shallow groundwater processes. The CAI1 and CAI2 of shallow groundwater ranged from \u0026minus;\u0026thinsp;6.3 to 0.81 and \u0026minus;\u0026thinsp;0.24 to 0.76, respectively, while the CAI1 and CAI2 of deep groundwater ranged from \u0026minus;\u0026thinsp;12.4 to 0.62 and \u0026minus;\u0026thinsp;0.31 to 0.22, respectively. This suggested that the intensity of the cation exchange is different for the shallow and deep groundwater.\u003c/p\u003e\u003cp\u003eThe slope and correlation coefficients of the equations for the shallow and deep groundwater (Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003eb) are \u0026minus;\u0026thinsp;1.88 (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.86) and \u0026minus;\u0026thinsp;0.34 (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.88), indicating that Ca\u003csup\u003e2+\u003c/sup\u003e, Mg\u003csup\u003e2+\u003c/sup\u003e, and Na\u003csup\u003e+\u003c/sup\u003e participate in ion exchange. However, significant differences were observed between the theoretical and actual values, implying that cation exchange is not the sole process affecting the concentration of the three ions. The other processes affecting the ion content include the discharge of mine drainage, and the interaction between groundwater and surface water. These processes affect ion content because of the high Na\u003csup\u003e+\u003c/sup\u003e content of mine drainage and surface water (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eTo better understand the hydrogeochemical processes in the aquifers, PHREEQC (Parkhurst and Appelo, \u003cspan class=\"CitationRef\"\u003e1999\u003c/span\u003e) was used to calculate the saturation indices of the major minerals. The saturation indices of minerals varied between \u0026minus;\u0026thinsp;0.5 and +\u0026thinsp;0.5, which indicates that groundwater is saturated (or in equilibrium) or near saturation with respect to these minerals. As shown in Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003ea and b, most of the groundwater samples are in a state of saturation or over-saturation with respect to calcite and dolomite. Almost all the groundwater samples are in a state of under-saturation with respect to gypsum and are highly unsaturated in terms of halite (Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003ec and d). Precipitation is the main source of groundwater in the study area. During the percolation of weakly acidic rain, carbonate minerals dissolve quickly and it is easy for groundwater to reach a dissolution equilibrium with calcite and dolomite. No significant correlation is observed between TDS and the SI values of calcite and dolomite. SI values of gypsum and halite, however, tend to increase with TDS, which indicates that the dissolution of gypsum and halite is one of the main processes involved in the increase in groundwater salinity.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"Section2\" id=\"Sec17\"\u003e\u003ch2\u003e4.4. Effects of anthropogenic activities on hydrochemistry\u003c/h2\u003e\u003cp\u003eThe Changzhi Basin has a long history of agricultural development, and the main crops grown are corn and wheat. Furthermore, the Changzhi Basin is located in southeastern Shanxi Province, near the location of the Jindong coal-based industries. Human activities associated with these socio-economic developments impose extensive impacts on the groundwater environment. These impacts stem from the use of fertilizers in the agricultural areas, water drainage during coal mining, and sewage discharge from urban areas.\u003c/p\u003e\u003cp\u003eGroundwater pollution caused by anthropogenic activities is a world-wide issue (Li et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). According to the monitoring results from 195 cities in China, 97% of urban groundwater has been polluted (Zhang, \u003cspan class=\"CitationRef\"\u003e2015\u003c/span\u003e). From Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, the following are observed of the NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e concentrations:\u003c/p\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e22 of the shallow groundwater samples exceed the limits of the level III quality standards for groundwater (20 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e as NO\u003csub\u003e3\u003c/sub\u003e-N), and have a mean value of 55.3 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e18 of the shallow groundwater samples exceed the limits of the level IV quality standards for groundwater (30 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e as NO\u003csub\u003e3\u003c/sub\u003e-N) and have a mean value of 65.68 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eSeven of the deep groundwater samples exceed the limits of the level III quality standards for groundwater and have a mean value of 47.44 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThree of the deep groundwater samples exceed the limits of the level IV quality standards for groundwater, and have a mean value of 76.28 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eThus, NO\u003csub\u003e3\u003c/sub\u003e-N pollution in the shallow groundwater is more serious than that in the deep groundwater, and mainly occurs in the central and northeastern agricultural areas, and in the urban area in the east of the basin. The main sources of NO\u003csub\u003e3\u003c/sub\u003e-N exceedance are fertilizer application and the discharge of human waste and sewage. The average nitrogen fertilizer application rate per ha of cultivated land is approximately 832.81 kg, which is far in excess of the average rate for China (339 kg/ha) (Chen et al., \u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eMine drainage during coal mining is also a cause for concern because of the relatively high Na\u003csup\u003e+\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, and TDS concentrations. When compared with the combined average values for shallow groundwater, deep groundwater, and surface water, the mine water has the following characteristics:\u003c/p\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eMean Na\u003csup\u003e+\u003c/sup\u003e content of mine drainage was 7.69\u0026ndash;23.87 times that of the combined average.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eMean Cl\u003csup\u003e-\u003c/sup\u003e content was 3.36\u0026ndash;7.56 times the average.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eMean SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e content was 1.86\u0026ndash;2.97 times the average.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eMean HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e content was 2.25\u0026ndash;3.29 times the average.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eMean TDS content was 2.16\u0026ndash;3.15 times the average.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eThe amount of mine drainage was 0.39\u0026nbsp;million m\u003csup\u003e3\u003c/sup\u003e\u0026middot;d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the Changzhi mining area, and was directly discharged into surface water, which interacts with groundwater, especially shallow groundwater, thus leading to an increase in Na\u003csup\u003e+\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, and HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e content of groundwater.\u003c/p\u003e\u003c/div\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eIn this study, the integrated approach consisting of Piper diagram, stable isotopes, Gibbs diagrams and ionic ratios provided an efficient way for analyzing the groundwater origin and hydrochemical processes that affected water chemistry. The Piper diagram and coefficient of variation were used to characterize the groundwater hydrochemistry and the stability of ions content; stable isotopes was a useful tool for analysis the origin and transformation of groundwater; Gibbs diagrams were used to establish the dominant effects of precipitation, rock weathering, or evaporation on geochemical evolution of groundwater, and deuterium excess was a capable way to quantify the contribution of evaporation to groundwater salinity; ionic ratios and saturation indices were used to depict the effects of mineral dissolution or precipitation on groundwater salinity. These methods were complementary of and verify each other. The main conclusions drawn are summarized as follows:\u003c/p\u003e \u003cp\u003eThe groundwater chemistry type of both shallow and deep groundwater demonstrates zonational characteristics from the west to east of the basin; the TDS content gradually increases (from 208.8 to 2,559 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and the types of hydrochemistry tend to be complex. In both shallow and deep groundwater, the hydrochemistry types are mainly HCO\u003csub\u003e3\u003c/sub\u003e-Ca and HCO\u003csub\u003e3\u003c/sub\u003e\u0026middot;SO\u003csub\u003e4\u003c/sub\u003e-Ca\u0026middot;Mg. The stable isotope compositions suggest that rain water is main recharge source for both shallow and deep groundwater. The interactions between shallow and deep groundwater, surface water and shallow groundwater and the lateral recharge from fissure groundwater at the edge of the basin have affected the isotopic composition of groundwater.\u003c/p\u003e \u003cp\u003eThe hydrochemical and isotopic interpretation showed that the hydrochemical composition of the groundwater was controlled by geochemical processes. Gibbs diagrams suggested that water-rock interaction was the main mechanism controlling groundwater chemistry. The deuterium excess method revealed that that mineral dissolution accounts for 81\u0026ndash;98% of the salinity of shallow groundwater and 84\u0026ndash;98% of deep groundwater. The dissolution of gypsum and halite makes a significant contribution to the increase of groundwater salinity. Overall, rock weathering in conjunction with the cation exchange absolutely predominated in the geochemical evolution of groundwater.\u003c/p\u003e \u003cp\u003eThe hydrochemical composition of groundwater in the study area is also affected by anthropogenic activities. NO\u003csub\u003e3\u003c/sub\u003e-N pollution occurs in the central area, the northeastern agricultural area, and the urban area in the east of the basin, and is more serious for shallow groundwater than for deep groundwater. The main sources of NO\u003csub\u003e3\u003c/sub\u003e-N are fertilizer application, human waste, and sewage. Mine drainage has relatively high concentrations of Na\u003csup\u003e+\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, and TDS when compared with shallow groundwater, deep groundwater, and surface water. Mine drainage is directly discharged into surface water and consequently interacts with groundwater, thus leading to an increase of Na\u003csup\u003e+\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, and HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e content of groundwater. The results of the present study provide a deeper insight into the water quality situation and geochemical evolution of groundwater, and will assist decision-makers to formulate sustainable groundwater management strategies for the study area.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflicts of interest \u003c/h2\u003e\n\u003cp\u003eThe authors declare no conflicts of interest.\u003c/p\u003e\n\u003ch2\u003eAcknowledgments\u003c/h2\u003e\n\u003cp\u003eThis work was supported by the Fundamental Research Funds for the Chinese Academy of Geosciences (No. JYYWF20180401) and the China Geological Survey project (No. DD20160296, DD20201123). We thank Paul Seward, PhD, from Liwen Bianji, Edanz Editing China (www.liwenbianji.cn/ac), for editing the English text of a draft of this manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAppelo C, Postma D (2004) Geochemistry, Groundwater and Pollution\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBelkhiri L, Boudoukha A, Mouni L et al (2011) Statistical categorization geochemical modeling of groundwater in Ain Azel plain (Algeria). Journal of African Earth Science 59:140\u0026ndash;148\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarol E, Mas-Pla J, Kruse E (2013) Interaction between continental and estuarine waters in the wetlands of the northern coastal plain of Samboromb\u0026oacute;n Bay, Argentina. Applied Geochemistry 34:152\u0026ndash;163\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChang J, Wang G (2010) Major ions chemistry of groundwater in the arid region of Zhangye Basin, northwestern China. Environmental Earth Science 61:539\u0026ndash;548\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen J, Wu H, Qian H (2016) Groundwater nitrate contamination and associated health risk for the rural communities in an agricultural area of Ningxia, northwest China. Expo Health 8:1\u0026ndash;11\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen J, Liu X, Wang C et al (2012) Isotopic constraints on the origin of groundwater in the Ordos Basin of northern China. Environmental Earth Science 66:505\u0026ndash;517\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen L, Zhang Y, Wang C (2012) A study of evolution of the discharge of the Xin\u0026rsquo;an spring with time series analysis. Hydrogeology Engineering Geology 39:19\u0026ndash;23 (in Chinese)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClark I, Fritz P (1997) Environmental Isotopes in Hydrogeology. Lewis Publishers, New York\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCook P, Herczeg A (1999) Environmental traces in subsurface hydrology. Kluwer, Dordrecht\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDansgaard W (1964) Stable isotopes in precipitation. Tellus 16:436\u0026ndash;468\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFarid I, Trabelsi R, Zouari K et al (2013) Hydrogeochemical processes affecting groundwater in an irrigated land in Central Tunisia. Environmental Earth Science 68:1215\u0026ndash;1231\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGibbs R (1970) Mechanisms controlling world water chemistry. Science 170:1088\u0026ndash;1090\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang G, Sun J, Zhang Y et al (2013) Impact of anthropogenic and natural processes on the evolution of groundwater chemistry in a rapidly urbanized coastal area, South China. Sci Total Environ 463\u0026ndash;464:209\u0026ndash;221\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang T, Pang Z (2012) The role of deuterium excess in determining the water salinisation mechanism: a case study of the arid Tarim River Basin, NW China. Applied Geochemistry 27:2382\u0026ndash;2388\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJamshidzadeh Z, Mirbagheri S (2011) Evaluation of groundwater quantity and quality in the Kashan Basin, Central Iran. Desalination 270:23\u0026ndash;30\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJia Y, Guo H, Xi B et al (2017) Sources of groundwater salinity and potential impact on arsenic mobility in the western Hetao Basin, Inner Mongolia. Sci Total Environ 601\u0026ndash;602:691\u0026ndash;702\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Z, Yang Q, Yang Y et al (2019) Isotopic and geochemical interpretation of groundwater under the influences of anthropogenic activities. Journal of Hydrology 576:685\u0026ndash;697\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Z, Wang G, Wang X et al (2018) Groundwater quality and associated hydrogeochemical processes in Northwest Namibia. Journal of Geochemical Exploration 186:202\u0026ndash;214\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu F, Song X, Yang L et al (2015) The role of anthropogenic and natural factors in shaping the geochemical evolution of groundwater in the Subei Lake basin, Ordos energy base, Northwestern China. Science of the Total Environment 538:327\u0026ndash;340\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMarfia A, Krishnamurthy R, Atekwana E et al (2004) Isotopic and geochemical evolution of ground and river waters in a karst dominated geological setting: a case study from Belize, Central America. Applied Geochemistry 19:937\u0026ndash;946\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcDonnell J, Beven K (2014) Debates-The future of hydrological sciences: a (common) path forward? A call to action aimed at understanding velocities, celerities and residence time distributions of the headwater hydrograph. Water Resource Research 50:5342\u0026ndash;5350\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMohanty A, Rao V et al (2019) Hydrogeochemical, seawater intrusion and oxygen isotope studies on a coastal region in the Puri District of Odisha, India. Catena 172:558\u0026ndash;571\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParkhurst D, Appelo C (1999) User\u0026rsquo;s guide to PHREEQC \u0026ndash; a computer program for speciation, reaction-path, 1D-transport, and inverse geochemical calculation. US Geological Survey Water Resources Investigations Report. 99-4259\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePlummer L, Busby J, Lee R et al (1990) Geochemical modeling of the Madison aquifer in parts of Montana, Wyoming, and South Dakota. Water Resour Res 26:1981\u0026ndash;2014\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQian H, Li P, Wu J (2013) Isotopic characteristics of precipitation, surface and groundwater in the Yinchuan plain, Northwest China. Environmental Earth Science 70:57\u0026ndash;70\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eS\u0026aacute;nchez D, Barber\u0026aacute; J, Mudarra M (2015) Hydrogeochemical tools applied to the study of carbonate aquifers: examples from some karst systems of Southern Spain. Environmental Earth Science 74:199\u0026ndash;215\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSandow M, Bruce B, Thomas M (2010) Analysis of groundwater quality using multivariate and spatial analyses in the Keta basin, Ghana. Journal of African Earth Sciences 58:220\u0026ndash;234\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchoeller H (1967) Geochemistry of Groundwater- an International Guide for Research and Practice\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSelvakumar S, Chandrasekar N, Kumar G (2017) Hydrogeochemical characteristics and groundwater contamination in the rapid urban development areas of Coimbatore, India. Water Resource Industry 17:26\u0026ndash;33\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSkrzypek G, Dogramaci S, Grierson P (2013) Geochemical and hydrological processes controlling groundwater salinity of a large inland wetland of northwest Australia. Chemical Geology 357:164\u0026ndash;177\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSun X (2008) The application of fuzzy judgement in karst groundwater quality of Xin\u0026rsquo;an spring region. Journal of Taiyuan University of Technology 39:418\u0026ndash;421 (in Chinese)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTizro T, Voudouris K (2008) Groundwater quality in the semi-arid region of the Chahardouly basin, West Iran. Hydrological Processes 22:3066\u0026ndash;3078\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang Y, Guo Q, Su C, Ma T (2006) Strontium isotope characterization and major ion geochemistry of karst water flow, Shentou, northern China. Journal of Hydrology 328:592\u0026ndash;603\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXing LN et al (2013) Groundwater hydrochemical characteristics and processes along flow paths in the North China Plain. J Asian Earth Science 70\u0026ndash;71:250\u0026ndash;264\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang Q, Li Z, Ma H et al (2016) Identification of the hydrogeochemical processes and assessment of groundwater quality using classic integrated geochemical methods in the Southeastern part of Ordos basin, China. Environmental Pollution 2:879\u0026ndash;888\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang R, Jin H, Hao X et al (2016) Assessment of karst groundwater vulnerability in Xin'an spring area based on modified RISKE model. Environmental Science Technology 39:170\u0026ndash;174 (in Chinese)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZang C, Dame J, N\u0026uuml;sser M (2018) Hydrochemical and environmental isotope analysis of groundwater and surface water in a dry mountain region in Northern Chile. Environ Monit Assess 190:334\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhai Y, Zheng F, Zhao X et al (2019) Identification of hydrochemical genesis and screening of typical groundwater pollutants impacting human health: A case study in Northeast China. Environmental Pollution 252:1202\u0026ndash;1215\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang C, Wang W, Sun Y et al (2015) Processes of hydrochemical evolution of groundwater in the Guanzhong basin, China. Journal of Groundwater Science Engineering 3:136\u0026ndash;146\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang H (2015) Risk assessment on Non-point Nitrogen Pollution in groundwater. Jilin University\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"environmental-earth-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"enge","sideBox":"Learn more about [Environmental Earth Sciences](https://www.springer.com/journal/12665)","snPcode":"12665","submissionUrl":"https://submission.nature.com/new-submission/12665/3","title":"Environmental Earth Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Groundwater, Hydrogeochemistry, Stable isotopes, Hydrochemical mechanisms, Anthropogenic activities, Coal mining","lastPublishedDoi":"10.21203/rs.3.rs-823775/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-823775/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe Changzhi Basin of China is an economically and ecologically important area with intensive human activities. To foster the sustainable development of groundwater resources and the economy, a total of 117 groundwater samples were collected in shallow and deep aquifers, including 91 \u003csup\u003e2\u003c/sup\u003eH and \u003csup\u003e18\u003c/sup\u003eO isotope samples, to improved understanding of the natural geochemical processes and the impacts of anthropogenic activities on the groundwater chemistry. Synthetical application of the stable isotopes, Piper diagram, Gibbs diagram, ionic ratios and saturation indices to data analysis led to identification of hydrochemical zones for both aquifers from west to east of the basin. Isotopic analyses suggested that the groundwater recharge mainly comes from infiltration of rain water, hydraulic interaction between surface water and shallow groundwater, and lateral recharge from fissure water at the edge of the basin. The predominant natural geochemical processes include mineral dissolution in conjunction with the cation exchange. The excess deuterium method revealed that mineral dissolution contributed 81%–98% to the salinity of shallow groundwater and 84%–98% to the salinity of deep groundwater. Anthropogenic activities are secondary contributions to the hydrochemical evolution with fertilizer application, human waste and sewage discharges causing an increase in NO\u003csub\u003e3\u003c/sub\u003e-N content and coal mining activities affecting the ion content of Na\u003csup\u003e+\u003c/sup\u003e, Cl\u003csup\u003e-\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e, and HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e in the groundwater.\u0026nbsp;\u003c/p\u003e","manuscriptTitle":"Stable Isotope and Hydrochemical Evolution of Groundwater in Mining Area of the Changzhi Basin, Northern China","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2021-11-01 15:23:10","doi":"10.21203/rs.3.rs-823775/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2021-10-15T14:44:04+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2021-10-15T14:29:02+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2021-08-18T02:53:43+00:00","index":"","fulltext":""},{"type":"submitted","content":"Environmental Earth Sciences","date":"2021-08-17T10:53:07+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"environmental-earth-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"enge","sideBox":"Learn more about [Environmental Earth Sciences](https://www.springer.com/journal/12665)","snPcode":"12665","submissionUrl":"https://submission.nature.com/new-submission/12665/3","title":"Environmental Earth Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"9c340243-f221-437f-9ccf-4fa51437b8ef","owner":[],"postedDate":"November 1st, 2021","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":8210441,"name":"Geology"},{"id":8210442,"name":"Environmental Chemistry"}],"tags":[],"updatedAt":"2022-04-20T02:48:27+00:00","versionOfRecord":[],"versionCreatedAt":"2021-11-01 15:23:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-823775","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-823775","identity":"rs-823775","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}