Hydrochemical Diagrams Research Articles

Hydrochemical variation characteristics and driving factors of surface water in arid Areas—a case study of Beichuan River in Northwest China

Examining the chemical properties of river water and the controlling factors is crucial for devising efficacious strategies in water resources management and ecological conservation. This study investigates the hydrochemical characteristics and driving factors of the Beichuan River in the arid region of Northwest China. Surface water samples were collected during wet and dry seasons, and analyzed using hydrochemical diagrams, mathematical statistics, and principal component analysis (PCA). The results show that the pH value of Beichuan River is generally weakly alkaline, the main hydrochemical types are HCO3-Ca, and the average TDS are 224 mg/L and 236 mg/L respectively, which are higher than the world average level (115 mg/L). The seasonal variation of hydrochemical components is mainly controlled by rainfall, showing that the concentrations of Na+, Cl− and NO3− in the wet season are higher than those in the dry season, while the concentrations of other chemical components show an opposite trend, while the spatial variation is mainly controlled by human activities, and the concentrations of hydrochemical components show a gradual increasing trend from upstream to downstream, especially Na+, Mg2+, Cl− and NO3−. Rock weathering is the key natural factor controlling the Hydrochemical Composition of Beichuan River. Na+ and Cl− are mainly from the dissolution of silicate, Ca2+ and Mg2+ are mainly from the weathering of carbonate rocks and silicate, and SO42- is mainly from the dissolution of evaporite. It is noted that human activities, especially domestic sewage and agricultural runoff, contribute significantly to NO3− in the water body. PCA identified rock weathering and agricultural runoff as major wet-season factors, while domestic sewage predominantly affects the dry season. This study can provide a scientific basis for the rational development of water resources and ecological environment protection in arid areas.

Investigation of the quality of the groundwater and the nitrate pollution hazards to human health in the desert region of Algeria

Groundwater in the desert zone is important for supporting all life forms in these regions. This research focused on analyzing the quality of groundwater and the threats posed by nitrate contamination in the Continental Intercalary Aquifer (CI) in the Adrar region. Twenty-five groundwater samples were collected and assessed for pH, electrical conductivity, and major ions, employing hydrochemical diagrams, multivariate statistical analysis, and indices such as the Pollution Index of Groundwater (PIG), Nitrate Pollution Index (NPI), and Health Risk Assessment (HRA).The findings revealed the typical order of ion concentrations: Na+ > Ca2+ > Mg2+ > K+ for cations and Cl- > SO42- > HCO3- > NO3- for anions. These concentrations result from natural processes like evaporation and the dissolution of evaporites, along with anthropogenic influences, primarily from agricultural and urban sources. The PIG values categorized 28% of samples as having insignificant pollution, 48% as low, and 24% as high. Moreover, NPI results showed that 24% of samples had insignificant pollution, 44% displayed mild pollution, and 32% were moderately polluted. The Health Risk Assessment highlighted significant non-carcinogenic risks due to nitrate exposure. Hazard quotient values exceeded the safe threshold of 1 in 80% of samples for infants, 76% for children, and 64% for adults, indicating significant health risks. These findings underscore the critical need for targeted treatment strategies to ensure safe drinking water for the region's population. This comprehensive analysis demonstrates the critical interplay between natural and human factors in shaping groundwater quality and emphasizes the importance of continued monitoring and intervention to protect public health.

Hydrochemical changes in thermal waters related to seismic activity: The case of the 2020–2021 seismic sequence in Granada (S Spain)

Between the end of December 2020 and August 2021, 3110 earthquakes were recorded in the Granada Depression in southern Spain, with 353 of them being felt by the population. The highest concentration of earthquakes occurred between January 23rd and February 23rd, 2021, during which five out of six of the highest magnitude earthquakes (greater than 4.1 Mw) were recorded. This shallow seismicity is associated with NW-SE normal active faults, specifically the Santa Fe fault. Hydrochemical sampling was carried out at two deep, upwelling, and thermal boreholes located near the epicentral zone between January 27th, 2021 and July 18th, 2022, to analyze the response of a set of hydrochemical parameters during and after the earthquakes. The methodology employed different statistical tools, including Principal Components Analysis (PCA), PHREEQC modeling as well as Piper and Langelier-Ludwig diagrams, to determine the hydrochemical evolution during the seismic sequence and the parameter variations in relation to the number and magnitude of the earthquakes. The results showed significant variations in almost all of the parameters analyzed, with greater variations in SO4, Cl, Fe, Ca, Zn, and Al. During the days with the highest number of earthquakes of the highest magnitude, there was a rapid increase in Cl, SO4, SiO2, and Mg, while F, T, EC, and pH decreased. Peaks in SO4 seemed to anticipate earthquakes of greater magnitude that could be related to the preseismic dilatation which allows for an inflow of deep sulphated source water into the aquifer system. PCA and hydrochemical diagrams showed appreciable differences between the two boreholes, which could be related to the sampling distance from the epicentral zone. The results suggest the need for a hydrochemical monitoring network in the region, which has the highest seismic hazard in Spain.

Hydrochemical Characteristics and Controlling Factors of Shallow and Deep Groundwater in the Heilongdong Spring Basin, Northern China

Heilongdong Spring Basin (HSB) is located in a semi-arid region in northern China. In the past few decades, it has been influenced by anthropogenic activities. Currently, there is a lack of information about the impact on the hydrogeochemistry and groundwater quality of different aquifers. To address this concern, the present study used conventional hydrochemical diagrams, stable isotope analysis and multivariate statistical techniques to analyze hydrochemical characteristics and controlling factors of shallow and deep groundwater in the study area. The results showed that all groundwater samples were weakly alkaline. The shallow groundwater (SGW) was mainly composed of SO4-Ca and SO4·HCO3-Ca·Mg water types with high TDS values. However, the predominant water types of deep groundwater (DGW) were HCO3-Ca·Mg and HCO3·SO4-Ca·Mg types with relatively low TDS. The large majority of shallow groundwater had poor water quality, which was influenced by natural factors and anthropogenic activities, characterized by high concentrations of SO42−, NO3−, and Cl−. In contrast, the overall water quality of deep groundwater was good, mainly controlled by the natural background. Nonetheless, a few karst groundwater samples of DGW in runoff areas exhibited close hydraulic connections with SGW samples and presented contamination to a certain degree. Our research results provide a scientific basis for the utilization and protection of groundwater in different aquifers in northern China.

Deciphering spatio-seasonal patterns, driving forces, and human health risks of nitrate and fluoride enriched water bodies in the Inner Mongolia Reaches of the Yellow River Basin, China.

The ecology and environment of the Yellow River Basin is threatened by fluoride and nitrate contamination induced by anthropogenic activity and geogenic factors. As a result, deciphering the spatio-temporal variability of fluoride and nitrate contamination in this area remains a challenge. Three hundred eighty-six samples of surface water and groundwater from the Inner Mongolia Reaches of the Yellow River Basin were taken for this investigation. According to the results of the multivariate statistical and geostatistical analyses, the fluoride pollution was primarily discovered in the middle and lower reaches of the study area and was determined to be more severe during the dry season. In contrast, nitrate contamination was found to be more severe during the wet season while being widely distributed in groundwater and concentrated in areas with intensive agricultural activities. The primary mechanisms governing the spatial-seasonal patterns of NO3- and F- pollution were shown by the principal component analysis, isotopic, and hydrochemical diagrams. The water-rock interaction or evaporation was crucial in the enrichment of F-. The human inputs (e.g., fertilizer or sewage) dominated fluoride and nitrate contamination. Additionally, the alkaline environment played a role in the generation of NO3- and F-. The health risk assessment concluded that the threat of fluoride contamination was greater than that of nitrate contamination. Children faced the greatest health risks, followed by females and males. These findings would serve as a guide for water management and pollution control in the Yellow River Basin.

Assessment of Groundwater Quality for Irrigation Purposes using Hydrochemical Diagrams and Chemical Indexes

Assessment of Groundwater Quality for Irrigation Purposes using Hydrochemical Diagrams and Chemical Indexes

Hydrochemical Response of Karst Groundwater to Rapid Urbanization in Xingtai, North China

Karst groundwater is the main water source for domestic, industrial, and agricultural needs in Xingtai City, North China. The objective of this study was to comprehensively access changes in the hydrochemical characteristics and evolution of karst groundwater in response to rapid urbanization. Water samples from the late 2010s and the 1970s were compared utilizing statistical analysis, hydrochemical diagrams, and inverse simulation technology. The total dissolved solids (TDS), total hardness (TH), NO3−, and Fe contents were significantly higher in the more recently obtained karst groundwater samples. Further, the dominance of HCO3-Ca-type water decreased, with new types emerging, relative to 1970s karst groundwater. Abnormal TDS, TH, SO42−, NO3−, and Cl− concentrations can be attributed to sewage discharge and fertilizer. Two groundwater discharge areas around the center of Xingtai City and Yangfan Town in the south of the study area were the most significantly affected by human activities. However, inverse modeling indicated that the dissolution of gypsum and halite, as well as cation-exchange processes, occurred in the groundwater paths during both periods. Recent increases in ion concentrations of karst groundwater in the study area have caused carbonate minerals to dissolve, resulting in a further increase of ion concentrations. The hydrochemical response and evolution of karst groundwater requires further study.

Fluoride occurrence in geothermal water of fault zone area, Southeast China

Fluoride (F−) is a common trace component in groundwater, and long-term exposure to high-F− groundwater is harmful to human health. Fluoride concentrations that exceed the World Health Organization guideline for drinking water (1.5 mg/L) have been detected in thermal and non-thermal groundwater from Southeast China, where the causes of the high fluoride occurrence are lack of study. To study the formation and migration mechanism of high fluoride groundwater from Southeast China, we carried out a systemic sampling of water samples in the surrounding area of Heyuan deep fault zone and Zijin-Boluo fault zone, then a comprehensive discussion including water hydrogeochemical, stable isotope composition, as well as hydrogeology analysis was conducted. Fluoride concentrations in geothermal and non-thermal water samples range from 1.11 to 22.76 mg/L and 0.04–8.3 mg/L, respectively. High temperature, alkaline conditions, and the depleted Ca2+ by reverse cation exchange and calcite precipitation would promote the release of fluoride from host rock to geothermal water. The availability of Ca-bearing and F-bearing minerals in host rock causes significant differences in fluoride concentrations between carbonate reservoir and granite reservoir. Hydrochemical diagrams reveal that the composition of groundwater is affected by mixing and that fractures act as the mixing channels in our study area. The addition of cold groundwater limits the fluoride concentrations by lowing temperature and increasing Ca2+ levels of geothermal water. Additionally, the relationship between F− and SiO2 indicates that geothermal water promotes the fluoride enrichment in cold groundwater, especially in confined aquifers which are more susceptible to geothermal water. The direct input of geothermal fluoride and secondary enrichment caused by alkaline condition contribute to the formation of high F− concentrations (7.2−8.3 mg/L) in confined groundwater. Our findings highlight that the natural evolution of geothermal systems in fault zone can result in the formation of geogenic contaminated groundwater.

Characteristics and Driving Factors of Hydrochemical Evolution in Tuochangjiang River Basin, Western Guizhou Province

Tuochangjiang River is a typical mining-type watershed in the karst mountainous area of western Guizhou province. The study of its hydrochemical evolution characteristics and driving factors is of great significance to the local economic development and the scientific management of water resources. The samples of river water, spring water, and mine water in the Tuochangjiang River Basin were collected, and the sources of solutes and their contribution to the chemical components of river water were discussed by means of hydrochemical diagrams, mathematical statistics, and the absolute principal component scores-multivariate linear regression model (APCS-MLR). The results showed that the pH of the river water ranged between 7.30 to 8.31, and the TDS value ranged between 40 to 520 mg·L-1, which was mainly contributed by Ca2+, Na+, HCO3-, and SO42-. The dominant cations in river water were Ca2+ and Na+, the dominant anions were HCO3- and SO42-, and the main water chemistry transitioned from HCO3-Ca to HCO3-Ca·Na and HCO3·SO4-Ca·Na type, whereas that of the mine water was mainly the HCO3-Na and HCO3·SO4-Na types. The chemical composition of river water was affected by rock weathering, exchange adsorption of anions, mineral dissolution and precipitation, and human activities, in which Ca2+, Mg2+, and HCO3- were mainly derived from the weathering and dissolution of carbonate and silicate rocks, Na+and SO42- were mainly from the discharge of mining wastewater, and Cl- and NO3- were affected by domestic sewage and agricultural activities, respectively. APCS-MLR analysis further showed that the river water solutes mainly included five sources:discharge of mining wastewater, dissolution of soil minerals, geological background, agricultural activities, and unknown sources, and their contribution rates to river water were 23.49%, 35.04%, 13.87%, 7.96%, and 20.63%, respectively. Mining factors and soil factors were the most important sources of solutes in the river water, and they were the main driving factors for the hydrochemical evolution of the Tuochangjiang River Basin.

HYDROGEOCHEMICAL MODELING OF GROUNDWATER OF THE QUATERNARY AQUIFER IN MELLAGOU VALLEY -BOUHMAMA- (NORTHEASTERN ALGERIA)

The use of groundwater in Bouhmama area for drinking and irrigation purposes has increased progressively over the past decade. The water quality of the aquifer has been significantly altered by anthropogenic activity, such as the extensive use of chemical fertilizers. This research intends to enhance our understanding of the hydrogeochemical function of the Mellagou aquifer in the Bouhmama area in northeastern Algeria. It contributes to the identification of the phenomena affecting the mineralization and the mechanisms of salinization of groundwater. A total of 15 groundwater samples were collected during the rainy seasons in 2022 distributed in the study area. In order to performed the results obtained this study used hydrochemical diagram (Piper, Schoeller, Stiff, Stabler, and Wilcox diagrams), thermodynamic models (saturation indexes), and statistical method (PCA). Three chemical facies with a predominance of the calcic bicarbonate facies reflect the influence of intercalations within the bicarbonate sedimentary formations. Groundwater mineralization is mainly governed by the dissolution and the precipitation of minerals (gypsum and halite, calcite and dolomite), Base Exchange, and anthropogenic activities. The results acquired by PCA show that the variables controlling water mineralization are Cl-, Na+, and K+.

Source and evolution of sulfate in the multi-layer groundwater system in an abandoned mine—Insight from stable isotopes and Bayesian isotope mixing model

The source and evolution of sulfate (SO42−) in groundwater from abandoned mines are widely concerned environmental issues. Herein, major dissolved ions, multi-isotopes (δ34S, δ18Osulfate, δ2H and δ18Owater), machine learning (Self-organizing maps) and Bayesian isotope mixing model were used to identify the source and evolution of SO42− in an abandoned mine (Fengfeng mine, northern China) with a multi-layer groundwater system. Groundwater in the study area was mainly divided into three clusters (Cluster I, Cluster II and Cluster III), dominated by Na-SO4, Ca-SO4 and Ca-HCO3 types, respectively. According to δ2H and δ18Owater, groundwater in the study area mainly originated from atmospheric precipitation. δ34S, δ18Osulfate and SO42− suggested that bacterial sulfate reduction did not affect the SO42− isotopic composition. Dual SO42− isotopes, and MixSIAR model revealed that the main source of SO42− in the study area was pyrite oxidation/gypsum dissolution, accounting for an average of 57.4 % (gypsum), 71.24 % (pyrite oxidation) and 52.93 % (pyrite oxidation) of SO42− in the samples of Clusters I–III, respectively. Combined with the hydrochemical diagrams, the evolution of SO42− in different clusters of samples was derived. Cluster I was mainly gypsum dissolution; In contrast, Clusters II and III were mainly pyrite oxidation accompanied by carbonate dissolution, and Cluster II was also influenced by cation exchange. These findings will help in developing management strategies for protecting groundwater quality, which will provide a reference for the study of solute sources and S cycling in abandoned mines.

Identifying the spatial pattern, driving factors and potential human health risks of nitrate and fluoride enriched groundwater of Ordos Basin, Northwest China

While the identification of the spatial patterns of fluoride (F−) and nitrate (NO3−) is important for groundwater management, these patterns remain poorly understood in the Ordos Basin. A total of 107 groundwater samples collected from phreatic aquifers were divided into three clusters using the self-organizing map (SOM). Cluster I, Cluster II and Cluster III represented the contaminated groundwater with different type and degree of pollution. On this basis, factor analysis (FA), together with classical hydrochemical diagrams reflected the major factors regulating the spatial characteristics of groundwater F− and NO3−. Firstly, water-rock interaction (carbonate precipitation, fluorite dissolution, and cation exchange) and evaporation were responsible for high groundwater NO3−, F−, hardness, and salinity. Secondly, anthropogenic inputs (agricultural activities and sewage) also contributed to high groundwater NO3− and F−. Finally, the universal alkaline environment could regulate groundwater NO3− and F−. Additionally, 68.22%, 37.38%, and 33.64% of samples showed higher total non-carcinogenic risk (HITotal > 1) for children, adult females, and adult males, respectively. Overall, the worst NO3− and F− contamination and health risks were evident in the western part of the Ordos Basin. The results of this study can contribute to the sustainable development of groundwater and to the protection of public health in the Ordos Basin.

Assessment of hydrogeochemical characteristics and saltwater intrusion in selected coastal aquifers of southwestern India

The principal objective of this study is to assess the saltwater intrusion and hydrogeochemical processes that affect groundwater geochemistry in the coastal aquifers of southwestern India. Groundwater samples were collected seasonally and the physico-chemical parameters determined on-site. Major ions were determined in the laboratory. Hydrochemical diagrams, ionic ratios, and multivariate statistical analysis were adopted for understanding the groundwater chemistry. Gibbs plot identified that rock-water interaction and evaporation were the mechanisms regulating hydrogeochemistry. Ionic ratios have shown that coastal wells were contaminated with saltwater intrusion during the pre-monsoon season. Hierarchical cluster analysis classified the samples based on their quality; sample clusters with high NO3− were in densely populated areas, whereas sample clusters with moderate salt content in the coastal areas. Another cluster showed high concentrations of salts, typically the zones of saltwater intrusion. The study concludes that influence of seasons, geogenic and anthropogenic factors contribute to the heterogeneous chemistry of groundwater.

Investigating sources, driving forces and potential health risks of nitrate and fluoride in groundwater of a typical alluvial fan plain

Groundwater of alluvial fan plains is the foremost water source, especially in arid/semiarid regions. Its contaminants are big issues for water supply and public health concern. To reveal the groundwater chemistry, contaminants sources and health threats in alluvial aquifers, 81 groundwaters were collected from a typical alluvial fan plain of northern China for nitrogen, fluoride and major ions analysis. Statistical analysis and hydrochemical diagrams as well as human health risk assessment were performed. Nitrate is widely distributed and 53% of groundwaters exceed the permissible limit with the maximum concentration up to 326 mg/L. The distributions of nitrite, ammonia and fluoride contaminants are sporadic in spatial, and the concentrations of fluoride in groundwaters are slightly beyond the permissible limit of 1 mg/L. The hydrochemical facies shift from HCO3-Ca or Mixed HCO3-Na·Ca type to Mixed Cl-Mg·Ca and ClCa type with the increase of nitrate content. Two factors (Factor-1 and Factor-2) are extracted by factor analysis and account 63% of the total variances. The positive loading of F− and negative loading of NO3− on Factor-2 reveal geogenic and anthropogenic origins, respectively. The significant positive loadings of TDS, TH, SO42−, Cl−, Ca2+, Mg2+ on Factor-1 reveal the governing mechanisms on groundwater chemistry by intermixed sources of geogenic origins and anthropogenic inputs. Hydrogeochemical evolution in the study area is driven by both water-rock interaction and anthropogenic forces. Anthropogenic inputs/influences are the dominated forces increasing groundwater nitrate content and salinity in the piedmont zone and the residential and industrial zone of the southeastern lower parts, and would pose potential non-carcinogenic risks to various populations via oral intake pathway. Rational measures should be taken to protect groundwater quality out of the threats of anthropogenic pollution. The geogenic fluoride in groundwater would threat the health of children through oral pathway and should be also concerned. CapsuleThe driving forces of groundwater chemistry in alluvial fan plains were revealed using integrated approach of factor analysis and geostatistical modelling.

Geochemical of Karst Water in the Western part of Gunungkidul District Area

The geological condition of the study area is included in the karst of the Panggang hydrogeological subsystem. This karst area is characterized by the presence of surface water and groundwater, which is distinctive, where the water is interesting to be studied, especially on its hydrochemistry. By knowing hydrochemistry, this research wants to know about the relationship between surface water and groundwater. The method was a hydrogeological survey and accompanied by hydrochemical testing of dolines (surface) water and groundwater. The data have been analyzed by some hydrochemical diagrams such as Schoeller, Piper, Durov, and Collins diagrams. Springs emerge from reef limestone aquifers (Gunungsewu aquifers) in several places, supported by grains, fractures, and channels porosities. Both groundwater and surface water are colorless (46 - 350 TCU) and clear (3 - 19 NTU) with a pH of 6.8 - 8.1 and TDS 76 - 308 ppm. Groundwater shows the Ca - bicarbonate and Ca, Mg - bicarbonate types, whereas dolines (surface) water has Ca, Mg - bicarbonate types. Groundwater and surface water show relatively similar hydrochemical facies. Enrichment of hydrochemical groundwater is greater in springs than in dolines. The doline water may not correlate with each other, and it means that the groundwater flows to dolines maybe not be interconnected. Thus, water in the karst area may flow in all directions, depending on the porosity of the controlling channels. Water in the study area is young, indicated by the Ca2+ and HCO3- dominant ions, supported by ion exchange and simple dissolution processes.

Ion migration process and influencing factors in inland river basin of arid area in China: a case study of Shiyang River Basin.

A thorough understanding of the processes and driving factors of ion migration, dilution, and enrichment in arid inland river basins is the basis for implementing water resources management. In this study, we analyzed the water chemistry of streamflow, groundwater, and precipitation and the behavior of main elements in the Shiyang River Basin by means of the hydrochemical diagram and multivariate statistical analysis. The spatial variation of water chemistry was obvious, and the conversion between different water bodies was frequent. The ions migrated from the mountain area to the oasis and desert and accumulated near the terminal lake finally. There were obvious differences in hydrochemistry between surface water and groundwater. From the mountain to the basin, the hydrochemical type of surfer water has varied, and the hydrochemical type of groundwater has changed from Ca-Cl type to Na-Cl type. The hydrochemistry of the basin was controlled by silicate weathering. However, the influence of water-rock interaction on surface water and groundwater was different, and the surface water was more complex. Significantly, agricultural activities and sewage discharge had a negative impact on the water environment. Interbasin water transfer (IBWT) was a form of external ions input from outside the basin, which affected the chemical characteristics of surface water in the lower reaches to a certain extent. In arid areas, human impact on water chemistry needs to be paid attention. These results are helpful to strengthen the understanding of the relationship between different regions and different water bodies in the arid basin.

Response of a Coastal Groundwater System to Natural and Anthropogenic Factors: Case Study on East Coast of Laizhou Bay, China.

With a shifting climate pattern and enhancement of human activities, coastal areas are exposed to threats of groundwater environmental issues. This work takes the eastern coast of Laizhou Bay as a research area to study the response of a coastal groundwater system to natural and human impacts with a combination of statistical, hydrogeochemical, and fuzzy classification methods. First, the groundwater level dynamics from 1980 to 2017 were analyzed. The average annual groundwater level dropped 13.16 m with a descent rate of 0.379 m/a. The main external environmental factors that affected the groundwater level were extracted, including natural factors (rainfall and temperature), as well as human activities (irrigated area, water-saving irrigated area, sown area of high-water-consumption crops, etc.). Back-propagation artificial neural network was used to model the response of groundwater level to the above driving factors, and sensitivity analysis was conducted to measure the extent of impact of these factors on groundwater level. The results verified that human factors including irrigated area and water-saving irrigated area were the most important influencing factors on groundwater level dynamics, followed by annual precipitation. Further, groundwater samples were collected over the study area to analyze the groundwater hydrogeochemical signatures. With the hydrochemical diagrams and ion ratios, the formation of groundwater, the sources of groundwater components, and the main hydrogeochemical processes controlling the groundwater evolution were discussed to understand the natural background of groundwater environment. The fuzzy C-means clustering method was adopted to classify the groundwater samples into four clusters based on their hydrochemical characteristics to reveal the spatial variation of groundwater quality in the research area. Each cluster was spatially continuous, and there were great differences in groundwater hydrochemical and pollution characteristics between different clusters. The natural and human factors resulted in this difference were discussed based on the natural background of the groundwater environment, and the types and intensity of human activity.

Hidroquímica das águas subterrâneas do Sistema Aquífero Barrei-ras na bacia do Rio Pirangi/RN

Este trabalho objetiva avaliar o comportamento hidroquímico das águas do Sistema Aquífero Barreiras (SAB) na área da Bacia Hidrográfica do Rio Pirangi - Região Metropolitana de Natal, segundo os diferentes aspectos ambientais do uso e ocupação do solo, com destaque para a avaliação dos efeitos do desenvolvimento urbano na qualidade das águas subterrâneas. Inicialmente, foi definida uma rede de monitoramento com 30 poços seguido de uma campanha de coletas e análises físico-químicas de amostras de água. A interpretação dos resultados foi efetuada com base em mapas de isovalores e diagramas hidroquímicos (Piper, Durov Expandido e Gibbs), sendo possível classificar as águas de acordo com fácies hidroquímicas e avaliar as modificaçoes hidrogeoquímicas nos diferentes contextos ambientais da área de estudo. Apesar das variações hidroquímicas observadas nos diferentes setores, de modo geral, as águas subterrâneas do SAB na área de estudo se caracterizam como levemente ácidas e de baixa salinidade, abrangendo predominantemente as fácies cloretadas sódicas magnesianas (Na+ - Mg2+ - Cl-) e cloretadas sódicas (Na+ - Cl-). Foi identificada contaminação das águas subterrâneas por nitrato em 30% das amostras, com destaque para as regiões mais urbanizadas. O aspecto climático é o principal fator controlador da química dessas águas, com a influência de fatores antrópicos do desenvolvimento urbano e de atividades agrícolas.

Hydrogeochemical Characteristics and Assessment of Drinking Water Quality in the Urban Area of Zamora, Mexico

This work assessed the groundwater hydrogeochemistry and the drinking water quality of 10 wells supplying the urban area of Zamora, Michoacán, Mexico. Two sampling campaigns were conducted in May 2018 (dry season) and November 2018 (wet season) to describe the chemistry of the water and its interaction with the rock. Physical and chemical constituents (temperature, pH, electrical conductivity, color, turbidity, solids, total hardness, total alkalinity, chemical and biochemical oxygen demands), major components (Ca2+, Mg2+, Na+, K+, SO42−, PO43−, HCO3−, CO32−, Cl−, N-NO3−, and N-NH3), as well as trace elements (As, Fe, Mn, Ba, Al, Sb, Co, V, Cu, Cd, Cr, Ni, Zn, Tl, Pb) were analyzed. Results showed groundwater with a slight tendency to alkalinity. The hydrogeochemical facies observed are Ca2+-HCO3− in all sites. Hydrochemical diagrams indicate immature, cold, non-saline, and uncontaminated water with short residence time. Water–rock interaction predominates. The water in the study area is appropriate for drinking use according to Mexican and international regulations with an excellent quality in 7 wells and good in the other 3.

Geochemical Modeling and Statistical Analysis for Groundwater Evolution Assessment in Wadi Qasab, Sohag, Eastern Desert, Egypt

Qasab basin is one of the most promising areas for the sustainable development in the Eastern Desert fringes of the Nile Valley, Egypt. The integration between statistical analysis, stable isotopes as well as geochemical modeling tools delineated the geochemical possesses affecting groundwater quality and detected the main recharge source in Qasab basin. The most of groundwater samples are brackish (88%), while the minority (12%) of the samples are fresh. The electrical conductivity of groundwater ranged from 1135 to 10,030 μS/cm. The statistical analysis and hydrochemical diagrams suggest that the groundwater quality is mainly controlled by several intermixed processes (rock weathering and agricultural activities). The mineralization of the Pleistocene groundwater is regulated by the rock weathering source, evaporation processes and reverse cation exchange. The isotopic signatures (δ2H and δ18O) represent two groundwater groups. The first group, is enriched with the isotopic signature of δ18O, which ranges from 0.9‰ to 5.5‰. This group is mostly affected by the recent meteoric recharge from the surface water leakage. The second group, is relatively depleted with the isotopic signature of δ18O, reflecting a palaeo recharge source of colder climate. The δ18O‰ varies from &#4510.1‰ to &#456.4‰, indicating upward leakage of the Nubian sandstone aquifer through deep seated faults. The inverse geochemical model reflects that the salinity source of the groundwater samples is due to the leaching and dissolution processes of carbonate, sulphate and chloride minerals from the aquifer matrix. This study can demonstrate the hydrochemistry assessment guide to support sustainable development in Qasab basin to ensure that adequate groundwater management can play to reduce poverty and support socioeconomic development.