Major Ions In Groundwater Research Articles

Effect of groundwater ions (Ca2+, Na+, and HCO3−) on removal of hexavalent chromium by Fe(II)-phosphate mineral

A systematic study was conducted to investigate the effect of major groundwater ions (i.e., Ca2+, Na+, and HCO3−) on removal of hexavalent chromium (Cr(VI)) by an Fe(II)-phosphate mineral (i.e., vivianite). The batch experiments revealed that the second-order rate constant for Cr(VI) removal by vivianite with Ca2+ + CO32− (0.076–1.90 mM) and Na+ + HCO3− (0.26–6.50 mM) was 1.5–5.2 times lower than that without these ions. The removal kinetics of Cr(VI) by vivianite was abruptly slowed down with the increased ion concentration, which showed their inhibitory effect on the reaction. The results of the geochemical modeling and density functional theory calculations showed that the presence of Ca2+ + HCO3− and Na+ + HCO3− can form less favorable Cr(VI) species (i.e., CaCrO4(aq) and NaCrO4−) on the Fe–B site of vivianite surface, leading to the inhibitory effect observed in this study. Finally, the X-ray absorption spectroscopy results showed that reductive immobilization of Cr(VI) to Cr(III) occurred by structural Fe(II) oxidation of vivianite to amorphous mixed-valence Fe-phosphate via an inner-sphere complexation. The results suggest that the presence of Ca2+, Na+, and HCO3− in phosphorous-enriched iron-reducing environments may lower the remedial efficiency of Cr(VI) removal.

Seasonal and geochemical variation of uranium and major ions in groundwater at Kanker district of Chhattisgarh, central India

The evaluation of groundwater quality is an imperative part of water security and plays a significant role in ensuring its sustainable development. The present paper reveals the quality of groundwater of Kanker district situated in Chhattisgarh state, India. Groundwater samples from different regions were collected to observe the seasonal variation in uranium concentration. The spatial distribution of major parameters and hydrochemical facies was described by Geographic Information System based maps, correlation coefficient, box plot, and piper diagrams. The uranium concentration ranges from 0.5 to 69.9 μg/L and 0.5–87.9 μg/L with the mean value of 4.8 μg/L and 6.8 μg/L in winter and summer season respectively. The uranium concentrations for the samples taken from one area in winter and two areas in summer have been found to be slightly higher than the permissible limit of 60 μg/L recommended by the Atomic Energy Regulatory Board. The seasonal variation of uranium in groundwater depends upon the rainfall recharge and precipitation conditions of the geological formation and the environment. In certain regions; it is observed that the total hardness, calcium, magnesium and total alkalinity (bicarbonate) were found higher than the acceptable limit prescribed by the Bureau of Indian Standards. Mixed type behaviors of tested samples were showed by the piper diagrams. Uranium exhibits a strong correlation with magnesium (r > 0.7) in both the seasons.

The Origin of Major Ions of Groundwater in a Loess Aquifer

When groundwater represents most of the world’s reserves of unfrozen freshwaters, water quality is commonly a limiting factor in quantifying usable fresh groundwater storage, especially in arid and semi-arid areas. Tracing the origin of major ions is important to the understanding of hydrochemical evolution and water–rock interaction. Strontium (Sr) and calcium (Ca) are geochemically similar in terms of ionic radius and ionic charge and can substitute for each other in mineral lattices such as in carbonates and silicates. This allows the use of Sr as a proxy for Ca during water–rock interaction. Geochemical mass balance and carbon and strontium isotope techniques were employed to study the origin of each major ion (such as Na, Ca, Mg, Cl, and SO4) in a loess aquifer (there is 10% to 20% of carbonate in the loess). Geochemical mass balance between atmospheric deposition and groundwater shows that the Cl (average concentration of 5.5 mg/L) and SO4 (average concentration of 6.8 mg/L) in groundwater originated from atmospheric deposition. The dissolution of loess using acetic acid was used to analyze the 87Sr/86Sr ratio of carbonate (mainly deposited in continental environments). Groundwater 87Sr/86Sr ratios (0.710677 to 0.712319) are consistent with 87Sr/86Sr ratios in carbonate (0.710329 to 0.711085) but are significantly lower than the whole-rock (0.715136 to 0.717155) and residue (0.719091 to 0.720438), suggesting that Ca and Mg mainly originated from the dissolution of carbonate in the loess aquifer. However, Na originated from the dissolution of albite, suggesting saturation controls the ability of dissolution. There are cation exchanges between Ca + Mg and Na, resulting in Na concentration increases and Ca + Mg concentration decreases in groundwater. This study is important to the understand of the origin of the major ions in groundwater and the geochemical processes in silicate-carbonate aquifers.

Major ion chemistry and water quality assessment of groundwater in the Shigaze urban area, Qinghai-Tibetan Plateau, China

Abstract Shigaze city is situated in the southwestern Tibetan Plateau and is the second largest city in the Tibet Autonomous Region. Groundwater is the major source of domestic and drinking water for urban inhabitants. In this study, the major ion chemistry and a water quality assessment of groundwater were studied using geochemical methods and fuzzy comprehensive assessment. Groundwater was classified as slightly alkaline soft and hard freshwater, and the influence of anthropogenic activities on groundwater was relatively weak. The dominant cations and anions were Ca2+ and Mg2+ and HCO3− and SO42−, respectively. Overall, the mean concentrations of major ions in groundwater increase gradually over time, except for NO3−; however, the mean value of pH decreases over time. Most groundwater samples belong to the type of HCO3-Ca, and the groundwater has a trend of evolution from HCO3-Ca to the mixed type. Rock weathering was the main hydrogeochemical process controlling groundwater hydrochemistry, and the dissolution of carbonate and silicate minerals were the primary contributors to the formation of the major ion chemistry of groundwater. Major ions of groundwater in the urban area of Shigaze are below the standard limits, and the groundwater is excellent for drinking according to the fuzzy comprehensive assessment.

Impact of road deicing salts on the Upper Passaic River Basin, New Jersey: a geochemical analysis of the major ions in groundwater

Road deicing salts, primarily sodium chloride, has been used widely to remove snow and ice from roadways in New Jersey and the northern United States since the 1950s. Currently, New Jersey stores up to 141 million kg of rock salt and 2401 m3 of liquid calcium chloride in the winter season for road deicing. Road deicing helps to reduce accident rates, road delays, and to improve road accessibility. While it is known that the use of road deicers is beneficial, road salts have also been shown to affect surface water and groundwater quality. In this study, an analysis of major ion concentration of groundwater collected by the United States Geological Survey (USGS) for the Upper Passaic River Basin (UPRB) was carried out. The UPRB has a large area of urban land use and a number of significant roads that are regularly deiced during the winter. The results of the study have shown that the contribution of Cl− to the TDS of groundwater increased significantly by the 2000s. Decadal bivariate plots of Na+ vs Cl− and Cl− vs TDS showed a strong increase in the correlations between these ions from the 1960s to the 2000s. Bivariate plots of Na+ vs Cl− and Ca2+ vs Mg2+ display a strong correlation, while those of Na+ vs Ca2+ and Cl− vs Ca2+ display a poor correlation. These observations suggest a link between Na+, Cl− and TDS, a link between Ca2+ and Mg2+, and no link between Ca2+ and Cl−, and between Ca2+ and Na+. Plots of Piper diagrams show that the groundwater facies have changed through time, starting as a single Ca(HCO3)2 species and shifting gradually towards a NaCl-dominated species. Plots of individual ion concentrations versus specific conductance show an increase in Na+ and Cl− over time and point towards an external influx of these ions. In general, groundwater in the UPRB is fresh with total dissolved solids less than 500 mg/L. Against the natural groundwater evolutionary trend, chloride is found to dominate over other chemical species in this freshwater system. These results provide evidence of a link between groundwater chlorides and road deicing salts in the UPRB.

Using GIS methods for determining the spatial distribution of groundwater hydrochemical facies: a case study for a shallow aquifer in Fuyang, China

The determination of groundwater hydrochemical facies (GHF) is useful for analyzing the chemical composition of groundwater, tracking sources of groundwater recharge and assessing how its chemical composition changes along groundwater flowpaths due to water–rock interactions. This paper proposes a geographical information systems (GIS)-based method for identifying and mapping the spatial distribution of GHF categories in an aquifer. Several procedures including spatial interpolation, raster reclassification, raster-to-vector conversion, spatial union overlay, and generalization methods are coupled in GIS tools to determine the type and distribution of GHF categories. This method was implemented to distinguish shallow GHF categories for a shallow aquifer near Fuyang City in Anhui Province, China. The results obtained from the GIS assessment of water quality data from 30 wells show there were seven types of hydrochemical facies identified in the study area. The major GHFs categories are HCO3–Na + K + Ca + Mg, HCO3–Ca + Mg, HCO3–Na + K + Ca, and HCO3–Na + K, which cover 94% of the total area. The GIS method correctly identified the GHF categories determined in 80% of the wells in the area. The major GHFs categories progressively change in the direction of groundwater flow from HCO3–Ca + Mg to HCO3–Na + K+Ca + Mg, then to HCO3–Na + K + Ca, and then to HCO3–Na + K. The changes in the proportions of major ions in groundwater, coupled with salinity increases in the direction of groundwater flow are due to the combined effects of water–rock interactions in the aquifer and human activities. The method can relatively efficiently identify and map GHF zones for aquifers.

Hydrochemical characteristics and possible controls in the groundwater of the Yarlung Zangbo River Valley, China

The Yarlung Zangbo River Valley is situated in the Qinghai Tibet Plateau with high elevation, abundant water resources and less influence from human activities. In this study, 47 groundwater samples were collected to investigate the hydrochemical characteristics and possible control of these characteristics in the groundwater of the Yarlung Zangbo River Valley; the samples were statistically analyzed using a Durov diagram, Gibbs plot, ratio graphs of ions, and factor analysis. The study results showed that the mean concentrations of the major ions in groundwater were relatively low, and the predominance of cations and anions in the groundwater was Ca2+ > Mg2+ > Na+ > K+ and HCO3− > SO42− > Cl−, respectively. Most groundwater samples fall in the category of HCO3–Ca and mixed HCO3·SO4–Ca·Mg. Upstream to downstream, the total dissolved solids and major cations and anions in the groundwater show a gradual decreasing trend due to the dilution effect of precipitation and lateral runoff recharge, except for the K+. The water–rock interaction was the primary mechanism controlling the groundwater chemistry in the study area. The dissolution of carbonates was the major contributor to the formation of the groundwater chemistry, and the dissolution of silicate and sulfate also contributed to the chemical composition of the groundwater in the study area, whereas the cation exchange was weak. In addition, H2SO4 participation in the dissolution and weathering of carbonate was an important source of SO42−.

Ion chemistry of groundwater and the possible controls within Lhasa River Basin, SW Tibetan Plateau

In order to study the major ion chemistry and controls of groundwater, 65 groundwater samples were collected and their major ions measured from wells within Lhasa River Basin. Groundwater has the characteristics of slightly alkaline and moderate total dissolved solid (TDS). TDS concentration ranged from 122.0 to 489.9 mg/L with a median value of 271.2 mg/L. Almost all the groundwater samples suited for drinking and irrigation. The major cations of groundwater are Ca2+ and Mg2+, accounting for 59.6 and 31.3% of the cations, respectively. Meanwhile, HCO3− and SO42− constituted about 56.7 and 36.9% of the anions, respectively, in Lhasa River Basin. The hydrochemical type of groundwater is HCO3-SO4-Ca-Mg. The chemical composition of groundwater samples located in the middle of Gibbs model, which indicates that the major chemical process of groundwater is controlled by rock weathering. Carbonate weathering was the dominant hydro-geochemical process controlling the concentration of major ions in groundwater within Lhasa River Basin, but silicate weathering also plays an important role.

Influence of a power plant in Ezhou City on the groundwater environment in the nearby area

To effectively protect shallow groundwater and to evaluate the environmental impact of groundwater, we set up a monitoring network of 30 monitoring wells and collected 11 water samples from the wells during the rainy and dry seasons. Hydrochemical characteristics of the shallow groundwater were identified with the Piper and Gibbs diagrams. Groundwater quality was assessed with the single standard index method and the entropy-weighted water quality index. Finally, we used a numerical simulation of the impact of the power plant operation on the groundwater environment. The average abundance of the major ions in groundwater from the dry to the wet season occurred in the following orders: Ca2+ > Na+ > Mg2+ > K+ for cations and HCO3− > SO42− > Cl− for anions. The shallow groundwater usually has elevated hardness and alkalinity values comparison with the standard values. The dominant hydrochemical facies of the groundwater is the HCO3–Ca type. Rock weathering is likely to be the dominant process that controls the groundwater chemical composition. Groundwater in the study area is suitable for drinking under ordinary conditions, according to the single standard index method and the entropy-weighted water quality index. However, the groundwater quality has been influenced by anthropogenic activities (including near the west Ash Yard and Huangji Sunaba). Numerical modeling shows that leakage during abnormal operating conditions is of limited extent within the boundary of the simulated area and does not enter into the Yangtze River. Overall, it is necessary to carry out effective anti-seepage and pollution control measures to ensure that shallow groundwater is not contaminated.

Hydrogeochemistry and quality of groundwater in a part of Damodar Valley, Eastern India: an integrated geochemical and statistical approach

The influence of geochemical processes and quality of groundwater in a rural tract of Damodar Valley region were investigated. The study has distinguished the groundwater as fresh, soft to moderately hard and mainly CaHCO3 type. The paired samples student’s t test shows the significant seasonal variations of pH, HCO3−, and Fe. Amphoteric exchange has lessened HCO3− concentration in post-monsoon which subsequently has caused to drop pH. Quite the reverse, the monsoon precipitation has triggered the additional release of Fe from iron-bearing sediments. The contaminant Cl− is from the domestic wastewater as is evidenced by field observations. The inter-variable relations, cation and anion mechanisms, and mineral saturation indices reveal that the dissolutions of silicate and carbonate minerals are the primary sources of major ions in groundwater. The chloro-alkaline indices showed the role of ion exchange too in water chemistry. The R-mode factor analysis also successfully identified two dominant processes regulating water chemistry—geogenic sources (Ca2+, Mg2+, Na+, and HCO3−) and anthropogenic inputs (mainly Cl−). The groundwater is found unsuitable for drinking at 82 and 93% of wells in pre- and post-monsoon seasons, respectively mainly due to elevated Fe content. The water from more than 90% of wells is appropriate for irrigation uses. The study recommends the proper treatment of contaminated water for consumption and measures to protect the groundwater from the waste water infiltration.

Ratio of Major Ions in Groundwater to Determine Saltwater Intrusion in Coastal Areas

Saltwater or seawater intrusion into groundwater aquifers occurs mostly in big cities and developing coastal cities. Coastal hydrology is associated with complex and highly dynamic environmental characteristics of interactions between groundwater, surface water, and water from the estuary. The rise of sea levels and excessive use of groundwater for clean water source trigger saltwater intrusion. Identification of saltwater intrusion into groundwater can be done by groundwater sampling and major ion analysis. The major ions dissolved in water are Ca, Mg, Na, K, Cl, HCO3, and SO4; the major ion ratios are Cl/Br, Ca/Mg, Ca/ (HCO3 and SO4), and Na/Cl. By knowing whether groundwater quality has been or has not been influenced by saltwater, groundwater zones can be determined in every coastal area. In addition, by analyzing and reviewing some concepts about the intrusion or contamination of saltwater into groundwater, there will be sufficient results for the identification of saltwater intrusion.

Hydrochemical analysis and evaluation of heavy metals in groundwater: A case study

The hydrochemical characteristics and the type of groundwater were identified in order to investigate the elements of major ions of groundwater samples in hydro-meteorology station located in Universiti Tun Hussien Onn Malaysia, UTHM. The objectives of the study were to measure the concentration of major ions and evaluate their chemical compositions . The measured ions were namely sodium (Na), magnesium (Mg), calcium (Ca), potassium (K), chloride (Cl), bicarbonate (HCO3), sulfate (SO4), heavy metals substance such as zinc (zn), ferum (Fe), copper (Cu), and manganese (Mn). Eight (8) groundwater samples were collected between January 2018 and March 2018 from a tubewell located at the Universiti Tun Hussein Onn Malaysia, Parit Raja, Johor followed by laboratory analyses by using Standard Methods for the Examination of Water and Wastewater. The concentrations of major cations and anions were determined and the concecutive strength were Na>Mg>K>Ca and Cl>HCO3>SO, respectively. Correlations among various pollutants were also observed. Strong correlations (p<0.01) were found between Total Dissolved Solid (TDS) and Electric Conductivity (EC). Both TDS and EC also showed strong positive correlations with Na, Mg, and Cl ions. The dispersal of major ions in groundwater was determined using piper diagram. The major cation and anion found were Na and Cl, respectively. The type of water that predominates in the study area was Na–Cl which indicated the groundwater influence from seawater intrusion. Mean concentrations for heavy metals parameters were also identified. The values milligram per litre (mg/L) were Mn (0.20), Cu (0.01), Fe (0.50) and Zn (0.04), respectively. Overall, the selected heavy metal parameters which were Mn, Cu, Fe and Zn met the Recommended Raw Water Standard by Ministry of Health, Malaysia.

Hydrogeochemical processes and contaminants enrichment with special emphasis on fluoride in groundwater of Birbhum district, West Bengal, India

The hydrogeochemistry of groundwater in rural parts of Birbhum district, West Bengal, India, has been studied to understand the contaminants and prime processes involved in their enrichment with a focus on F− concentration. The lithological units consist of Quaternary alluviums with underlying Rajmahal basaltic rocks of Middle Jurassic age. Groundwater occurs in the alluviums, weathered residuum and fracture zone of Rajmahal rocks. Studies show elevated concentration of Cl−, SiO2, Fe and F−; excess Cl− is attributed to anthropogenic inputs, SiO2 is ascribed to high degree of weathering of silica rich host rocks, and high Fe is due to the interaction of water with Fe-rich sediments under reducing condition. The F− concentration is found high (>1.20 mg/L) mainly in water from Rajmahal rocks revealing a lithological control on F− enrichment. The weathering of silicates and ion exchange are the leading controlling processes for major ions in groundwater. The F− enrichment is due to the dissolution of F−-bearing minerals and perhaps also through anion exchange (OH− for F−) on clay minerals at high alkaline conditions; precipitation of CaCO3 favours CaF2 dissolution leading to elevated F− concentration. CaHCO3, the dominant water type, contains low F− while NaHCO3 and NaCl types exhibit high F− concentrations. Among the three spatial associations, Cluster-1 and Cluster-2 are CaHCO3 type; Cluster-3 shows NaHCO3 and NaCl waters with low Ca2+ and Mg2+ and high Na+ contents. Cluster-1 and Cluster-2 waters are, in general, drinkable barring the elevated Fe content, while Cluster-3 water is unsafe for drinking due to the high F− concentration.

Spatial interpolation methods and geostatistics for mappinggroundwater contamination in a coastal area.

Mapping groundwater contaminants and identifying the sources are the initial steps in pollution control and mitigation. Due to the availability of different mapping methods and the large number of emerging pollutants, these methods need to be used together in decision making. The present study aims to map the contaminated areas in Richards Bay, South Africa and compare the results of ordinary kriging (OK) and inverse distance weighted (IDW) interpolation techniques. Statistical methods were also used for identifying contamination sources. Na-Cl groundwater type was dominant followed by Ca-Mg-Cl. Data analysis indicate that silicate weathering, ion exchange and fresh water-seawater mixing are the major geochemical processes controlling the presence of major ions in groundwater. Factor analysis also helped to confirm the results. Overlay analysis by OK and IDW gave different results. Areas where groundwater was unsuitable as a drinking source were 419 and 116km2 for OK and IDW, respectively. Such diverse results make decision making difficult, if only one method was to be used. Three highly contaminated zones within the study area were more accurately identified by OK. If large areas are identified as being contaminated such as by IDW in this study, the mitigation measures will be expensive. If these areas were underestimated, then even though management measures are taken, it will not be effective for a longer time. Use of multiple techniques like this study will help to avoid taking harsh decisions. Overall, the groundwater quality in this area was poor, and it is essential to identify alternate drinking water source or treat the groundwater before ingestion.

Hydrogeochemical features of groundwater resources in Tabriz plain, northwest of Iran

The present study seeks to evaluate the hydrogeochemistry of Tabriz plain in NW Iran, through major ion chemistry and their spatial variations. In order to accomplish these, groundwater sampling from 30 shallow and deep wells in the plain were carried out in July 2012. The water samples were analyzed for various physicochemical parameters such as pH, EC, Na+, Ca2+, K+, Mg2+, Cl−, CO32−, HCO3−, SO42− and NO3−. Chadha’s diagram demonstrates that most of the groundwaters belonged to the Na–Cl and mixed Ca–Mg–Cl hydrochemical facies. The concentrations of some major ions in groundwater are above the permissible limit for drinking and domestic purposes except for a few locations. The results of saturation index computation show that dissolution of gypsum, anhydrite, halite and silicate minerals occurs frequently across the study area, whereas the groundwater is supersaturated with regard to calcite and dolomite. Cross-plots show that weathering and dissolution of different rocks and minerals, ion exchange, reverse ion exchange and anthropogenic activities, especially agricultural activities, are effective in hydrogeochemistry of the study area.

Using stable isotopes and major ions to identify hydrogeochemical characteristics of karst groundwater in Xide country, Sichuan Province

Karst groundwater is important water resources for local people in southwest China, especially in Xide country, Sichuan Province. Stable isotopes (H and O) that incorporated with major ions of groundwater were used to identify the origin of groundwater, and determine the dominant water–rock interaction processes controlling the hydrogeochemical characteristics of groundwater in the study area. The stable isotopes results indicated that all groundwater derived from meteoric water. The chemical analysis showed that the cold groundwater was HCO3-Ca·Mg type, and the thermal water was HCO3·SO4-Ca·Mg type. The major ions of groundwater combined with the equilibrium stated of the groundwater based on the saturation index (SI), suggested that the hydrogeochemical characteristic of groundwater was mainly governed by dissolution of carbonate minerals and gypsum rocks, and ion exchange. Other factors such as evaporation and anthropogenic activities may also play roles on it. The results revealed the dominant hydrogeochemical processes controlling groundwater water quality in this karst area, which would provide significant insights into the local governments that can make effective policy for groundwater utilization.

Spatial Variability and Contamination Levels of Fresh Water Resources by Saline Intrusion in the Coastal Low Lying Areas of the Douala Metropolis-Cameroon

A study based on the spatial variability and contamination levels of fresh water resources by saline intrusion was conducted in the Douala coastal area. The study was aimed at highlighting the associations between major ions in ground water from which cause-effect relationships could be inferred. Water samples were collected from 19 stations. 3 stations were selected from the mangrove area and 16 stations were selected from the rest of the area partitioned into four transects (coastal transect, inner transect 1, inner transect 2 and inner transect 3). Sampling was done repeatedly during the dry season and these samples were analysed for physico-chemical parameters. Results show that the samples were acidic (pH: 4.7 - 6.7). Total dissolved solids (TDS) and electrical conductivity (EC) values ranged between 70.3 - 3703 mg/L and 136.4 - 7333 μS/cm respectively indicating medium salt enrichment and brackish waters. High temperatures (T°C) and low dissolved oxygen (DO) values of 26°C - 30.3°C and 0.96 - 3.9 mg/L respectively were observed and this could be interpreted as the acceleration of biological and chemical processes of ground water resources. Major ions were within the WHO limits except for Ca2+ (20.3 - 85 mg/L) and Mg2+ (6.6 - 49.6 mg/L) respectively whose concentrations were slightly higher. The leading cations were Ca2+ > Na+ > Mg2+ > K+ while were the leading anions. The multivariate analysis approach (MAA) values obtained for water variables showed that F1, F2 and F3 accounted for 61.6%, 21.5% and 9.9% respectively of total variance with strong loadings and these were considered to account for the ground and surface water quality of the area. The main water types were 63.2% , 26.3% Ca2+-Cl- and 10.5% Na+-Cl-. 89.5% of the water types had secondary salinity implying that anthropogenic sources were the source of salinity. The water was not fit for drinking. The values calculated for percentage sodium and sodium absorption ratio to determine its suitability for agricultural purposes revealed that 63.15%, 15.5%, 5.3% and 15.8% of sampled water were excellent, good, doubtful and unsuitable respectively for irrigation purposes. The need for water resource monitoring and forecasting regarding deterioration in quality is imperative before hazards of the rise in sea level arise.

Characters of hydrochemistry and their influenced factors of different waters in the Linhuan coal mining subsidence area of Huaibei City

为研究淮北临涣矿采煤沉陷区不同水体的补给水源及溶质来源，在现场调查的基础上，系统采集丰水期、平水期、枯水期沉陷区积水、地表河水和浅层地下水样进行测试分析，采用Piper三线图、Gibbs图和因子分析方法，对不同水体水化学特征及其影响因素进行讨论.结果表明：地表水水体总溶解性固体（TDS）质量浓度表现为枯水期>丰水期>平水期，浅层地下水表现为枯水期>平水期>丰水期，地表水TDS质量浓度明显高于浅层地下水.地表水中主要阴阳离子为Na⁺、Cl^-和SO₄^2-，水化学类型主要为SO₄^2--Cl^--Na⁺型；浅层地下水离子以HCO₃^-、Ca²⁺和Mg²⁺为主，表现为HCO₃^--Ca²⁺-Mg²⁺型.结合Gibbs图和因子分析可知，地表水受蒸发作用、地表径流以及采煤活动等因素影响，浅层地下水在一定程度上体现出大气降水和地表水补给的特点，受岩石风化作用影响较为明显.;In order to research the interaction of water sources and dissolved solids in surface water and groundwater in the Linhuan coal mining subsidence area,81 water samples were collected from surface water and groundwater during the periods of wet period,median water period,and dry period.The concentrations,compositions and types of major ions were analyzed.The influence factors were discussed by Piper graph,Gibbs graph and the method of factor analysis.The results indicate that:Total dissolved solids (TDS) are in the order of dry season > wet season > median water period in surface water,and in the order of dry period > median water period > wet period in groundwater.The TDS of surface water are obviously higher than those of groundwater.Na⁺,Cl^-and SO₄^2- are major ions in surface water,and mainly belong to the water chemistry type of SO₄^2--Cl^--Na⁺.HCO₃^-,Ca²⁺ and Mg²⁺ are major ions in groundwater,and belong to the water chemistry type of HCO₃^--Ca²⁺-Mg²⁺.The Gibbs graph and factor analysis show that intense evaporation process,surface runoff and mining activities occurred in the surface water.To a certain extent,shallow groundwater reflects the characteristics of atmospheric precipitation and recharges of surface water,which is mainly influenced by rock weathering degrees.

Hydrogeochemical characterization and suitability assessment of groundwater in an agro-pastoral area, Ordos Basin, NW China

Groundwater is vital to supply residents, livestock and agriculture in Daniudi gasfield area, which is a typical agro-pastoral area. To effectively protect and rationally utilize the groundwater, a hydrochemical investigation of 43 samples from this area was conducted. A hydrogeochemical assessment using a Piper diagram, correlation analysis, ratios of major ions, principle component analysis and saturation index calculations was carried out to detect the hydrochemical characteristics and evolution processes of the groundwater from a Quaternary aquifer (QA) and a Cretaceous aquifer (KA), and fuzzy synthetic evaluation and some water quality indices were applied to assess groundwater suitability for drinking and irrigation. According to the statistic summary, the average abundance of the major ions in groundwater from the QA and KA follows the order: HCO3 − > SO4 2− > Cl− for anions and Ca2+ > Na+ > Mg2+ > K+ for cations. There is evidence that the chemical composition of groundwater in the region has been influenced by human activities. The dominant hydrochemical facies of the groundwater is HCO3–Ca type. Dissolution of carbonate and evaporite minerals and the weathering of silicate minerals are likely to be the sources of major ions in groundwater. Ion exchange is another significant factor affecting the groundwater constituents. Gibbs diagrams suggest that rock weathering is the control process of groundwater chemical composition. As to suitability of groundwater for drinking, single parameter comparison and fuzzy comprehensive evaluation reveal that most of the groundwater in the study area is suitable for drinking under ordinary condition. A US Salinity Laboratory diagram, Wilcox diagram and some irrigation indices indicate that more than 90 % of the groundwater samples are suitable for use in irrigated agriculture.

Identification of the hydrogeochemical processes and assessment of groundwater quality using classic integrated geochemical methods in the Southeastern part of Ordos basin, China

Insufficient understanding of the hydrogeochemistry of aquifers makes it necessary to conduct a preliminary water quality assessment in the southern region of Ordos Basin, an arid area in the world. In this paper, the major ions of groundwater have been studied aiming at evaluating the hydrogeochemical processes that probably affect the groundwater quality using 150 samples collected in 2015. The two prevalent hydrochemical facies, HCO3Mg·Na·Ca and HCO3Mg·Ca·Na type water, have been identified based on the hydrochemical analysis from Piper trilinear diagram. Compositional relations have been used to assess the origin of solutes and confirm the predominant hydrogeochemical processes responsible for the various ions in the groundwater. The results show that the ions are derived from leaching effect, evaporation and condensation, cation exchange, mixing effect and human activities. Finally groundwater quality was assessed with single factor and set pair methods, the results indicate that groundwater quality in the study region is generally poor in terms of standard of national groundwater quality. The results obtained in this study will be useful to understand the groundwater quality status for effective management and utilization of the groundwater resource.