Search Results (35)

A gypsum karst sinkhole at Westeregeln (north-central Germany) was filled during the Late Pleistocene, first by fluvial flooding, then by solifluctation, and finally with wind-transported loess. Pleistocene mollusks and bones of snakes, birds, micro- and macromammals, and hyena coprolites were accumulated, often mixed in gravel or sand layers with Middle Paleolithic artifacts, whereas ice wedges reach deep into the sinkhole. The high amount of small flint debris prove on-site tool production by using 99% local Saalian transported brownish-to-dark Upper Cretaceous flint, which could have been collected from the Bode River gravels near-site. Only a single quartzite and one jasper flake prove other local gravel sources or importation. A large bifacial flaked knife of layer 4 dates to the early/middle Weichselian/Wuermian (MIS 5-4), similar to two triangular handaxes in the MTA tradition and an absolutely dated woolly rhinoceros bone (50,310 + 1580/−1320 BP). A cold period of Late Pleistocene glacial mammoth steppe megafauna is represented, but the material is mostly strongly fragmented and smashed by humans. Neanderthal camp use on the gypsum hill is indicated also by small charcoal pieces, burned bone fragments, and fire-dehydrated flint fragments. Crocuta crocuta spelaea (Goldfuss) hyenas are well known from Westeregeln, with an open-air commuting den site, which was marked with feces. Full article

Rapid socio-economic development and the impact of human activities have exerted tremendous pressure on the groundwater system of the Dawen River Basin (DRB), the largest tributary in the middle and lower reaches of the Yellow River. Hydrochemical studies on the DRB have largely centered on the upstream Muwen River catchment and downstream Dongping Lake, with some focusing solely on karst groundwater. Basin-wide evaluations suggest good overall groundwater quality, but moderate to severe contamination is confined to the lower Dongping Lake area. The hydrogeologically complex mid-reach, where the Muwen and Chaiwen rivers merge, warrants specific focus. This region, adjacent to populous areas and industrial/agricultural zones, features diverse aquifer systems, necessitating a thorough analysis of its hydrochemistry and origins. This study presents an integrated hydrochemical, isotopic investigation and EWQI evaluation of groundwater quality and formation mechanisms within the multiple groundwater types of the central DRB. Central DRB groundwater has a pH of 7.5–8.2 (avg. 7.8) and TDSs at 450–2420 mg/L (avg. 1075.4 mg/L) and is mainly brackish, with Ca²⁺ as the primary cation (68.3% of total cations) and SO₄²⁻ (33.6%) and NO₃⁻ (28.4%) as key anions. The Piper diagram reveals complex hydrochemical types, primarily HCO₃·SO₄-Ca and SO₄·Cl-Ca. Isotopic analysis (δ²H, δ¹⁸O) confirms atmospheric precipitation as the principal recharge source, with pore water showing evaporative enrichment due to shallow depths. The Gibbs diagram and ion ratios demonstrate that hydrochemistry is primarily controlled by silicate and carbonate weathering (especially calcite dissolution), active cation exchange, and anthropogenic influences. EWQI assessment (avg. 156.2) indicates generally “good” overall quality but significant spatial variability. Pore water exhibits the highest exceedance rates (50% > Class III), driven by nitrate pollution from intensive vegetable cultivation in eastern areas (Xiyangzhuang–Liangzhuang) and sulfate contamination from gypsum mining (Guojialou–Nanxiyao). Karst water (26.7% > Class III) shows localized pollution belts (Huafeng–Dongzhuang) linked to coal mining and industrial discharges. Compared to basin-wide studies suggesting good quality in mid-upper reaches, this intensive mid-reach sampling identifies critical localized pollution zones within an overall low-EWQI background. The findings highlight the necessity for aquifer-specific and land-use-targeted groundwater protection strategies in this hydrogeologically complex region. Full article

With the intensification of human activities, the water resource environment in the karst mountainous area of central Shandong has undergone significant changes, directly manifested in the cessation of karst spring flows and the occurrence of karst collapses within the spring basin in the Laiwu Basin. To support the scientific development and management of karst water, this study utilizes comprehensive analysis and deuterium-oxygen isotope test data from surveys and sampling of 20 typical karst springs conducted between 2016 and 2018. By integrating mathematical statistics, correlation analysis, and ion component ratio methods, the study analyzes the genesis, hydrochemical ion component sources, and controlling factors of typical karst springs in the Laiwu Basin. The results indicate that the genesis of karst springs in the Laiwu Basin is controlled by three factors: faults, rock masses, and lithology, and can be classified into four types: water resistance controlled by lithology, by faults, by basement, and by rock mass. The karst springs are generally weakly alkaline freshwater, with the main ion components being HCO₃⁻ and Ca²⁺, accounting for approximately 55.02% and 71.52% of the anion and cation components, respectively; about 50% of the sampling points have a hydrochemical type of HCO₃·SO₄-Ca·Mg. Stable isotope (δ¹⁸O and δD) results show that atmospheric precipitation is the primary recharge source for karst springs in the Laiwu Basin. There are varying degrees of evaporative fractionation and water–rock interaction during the groundwater flow process, resulting in significantly higher deuterium excess (d-excess) in the sampling points on the southern side of the basin compared to the northern side, indicating clear differentiation. The hydrochemical composition of the karst groundwater system is predominantly governed by water–rock interactions during flow processes and anthropogenic influences. Carbonate dissolution (primarily calcite) serves as the principal source of HCO₃⁻, SO₄²⁻, Ca²⁺, and Mg²⁺, while evaporite dissolution and reverse cation exchange contribute to the slight enrichment of Ca²⁺ and Mg²⁺ alongside depletion of Na⁺ and K⁺ in spring waters. Saturation indices (SI) reveal that spring waters are saturated with respect to gypsum, aragonite, calcite, and dolomite, but undersaturated for halite. The mixing of urban domestic sewage, agricultural planting activities, and the use of manure also contributes to the formation of Cl⁻ and NO₃⁻ ions in karst springs. Full article

Alcalá de Ebro is located 35 km northwest of the city of Zaragoza, on the right bank of the Ebro River at the outlet of a ravine (Juan Gastón) towards the river, with a catchment area of more than 230 km². Over time, urbanisation and agricultural development have eliminated the last stretch of the drainage channel, and these water inputs have been channelled underground, filtering through the ground. This section of the Ebro Valley rests on a marly tertiary substratum, which promotes dissolution-subbing processes that can lead to sinkholes. The ground tends to sink gradually or suddenly collapse. Many studies have been carried out to understand not only the origin of the phenomenon but also its geometry and the area affected by it in the town of Alcalá de Ebro. In this sense, it has been possible to model an area around the main access road, where numerous collapsing sinkholes have been found, blocking the road and affecting houses. It also affects the embankment that protects the town from the floods of the river Ebro. These studies have provided specific knowledge, enabling us to evaluate and implement underground consolidation measures, which have shown apparent success. Several injection campaigns have been carried out, initially with expansion resins and finally with columnar development, using special low-mobility mortars to fill and consolidate the undermined areas and prevent new subsidence. These technical solutions propose a method of ground treatment that we believe is novel for this type of geological process. The results have been satisfactory, but it is considered necessary to continue monitoring the situation and to extend attention to a wider area to prevent, as far as possible, new problems of subsidence and collapse. In this sense, the objective is to continue the control and monitoring of possible phenomena related to subsidence problems in the affected area and its immediate surroundings, to detect and, if necessary, anticipate subsidence or collapse phenomena that could affect the body of the embankment. Full article

The gypsum karst of Sorbas (Almería, Spain) is home to a diverse community of Collembola. Over seven years of sampling, 7875 specimens were collected from 83 cave visits, representing four orders: Symphypleona (5251 specimens), Entomobryomorpha (2552), Poduromorpha (32), and Neelipleona (29). A total of 25 species were identified. The most abundant are listed in descending order of abundance: Pygmarrhopalites ruizporteroae sp. nov., Pseudosinella najtae, Pygmarrhopalites subbifidus, Troglopedetes machadoi, Pseudosinella sexocellata sp. nov., Pygmarrhopalites torresi sp. nov., and Heteromurus major. Additionally, partial redescriptions of Pseudosinella najtae and Troglopedetes machadoi are provided. This research enhances the taxonomic framework of subterranean Collembola and provides new insights into species differentiation and adaptation. The methodologies applied allow for high-resolution morphological characterization, essential for species delimitation. The results highlight the potential for further discoveries in gypsum caves and emphasize the need for advanced imaging techniques in Collembola taxonomy. Full article

The source of sulfate in the groundwater of karst springs in the northern Taihang Mountains remains unclear due to the influence of multiple factors. To investigate this, 33 sampling points were selected in August 2022 across the exposed, covered, and buried areas of the spring basin, and water samples were collected. Hydrochemistry and sulfur–oxygen dual isotope methods were employed to examine the distribution characteristics of sulfate, δ¹⁸O_SO4, and δ³⁴S_SO4. Based on the distinct characteristics of sulfur isotopes from different sources, the sources of sulfate in various environments were qualitatively analyzed. Additionally, the contribution rates of each source were quantitatively determined using a Bayesian stable isotope mixing model. The results showed that the sulfate content in karst groundwater ranged from 16.68 to 156.84 mg/L, with an average of 62.22 mg/L, and indicated an increasing trend from exposed to covered to buried areas. The δ³⁴S_SO4 values in karst groundwater ranged from 3.1‰ to 13.5‰, with an average of 6.49‰, while the δ¹⁸O_SO4 values ranged from 2.9‰ to 10.3‰, with an average of 5.49‰. The δ³⁴S_SO4 values showed a general increasing trend across the exposed, covered, and buried areas, whereas the δ¹⁸O_SO4 values remained relatively stable across these areas. The analysis revealed that the primary sulfate sources in the exposed area were atmospheric precipitation, soil sulfate, chemical fertilizer, and sewage, contributing 19.6%, 63.5%, 9.4%, and 7.5%, respectively. In the covered area, the main sources were atmospheric precipitation, sulfide oxidation, soil sulfate, and gypsum dissolution, with contributions of 16.5%, 58.7%, 15.9%, and 8.9%, respectively. In the buried area, the sulfate primary originated from atmospheric precipitation, sulfide oxidation, and gypsum dissolution, contributing 11.6%, 78.5%, and 9.9%, respectively. This study provides critical insights into the sulfate sources in different environments, enhancing the understanding of groundwater sulfate pollution in the study area. These findings provide a scientific foundation for managing groundwater pollutants and resources in the karst regions of northern China. Full article

The Ordovician dolomite in the Ordos Basin is an important natural gas reservoir. Exploring dolomite genesis and the factors influencing reservoir characteristics is essential for deep carbonate rock exploration. This study offers a comprehensive analysis of dolomite evolution using methods such as thin-section petrography, isotope analysis, and trace and rare earth elements. The analysis shows that: Based on petrographic observations of the Majiagou Formation in the study area, the dolomite in the study area can be divided into residual oolitic dolomite of synsedimentary or metasomatic origin, micritic dolomite of secondary metasomatism or recrystallization origin, powder crystal dolomite, and fine crystal dolomite. Reservoir pores mainly develop intergranular pores, mold pores, dissolved pores, and fractures. Combined with the characteristics of major elements, trace elements, carbon and oxygen isotopes, rare earth elements, and inclusions in the study area, it can be concluded that the fifth member dolomite of the Majiagou Formation is of shallow–medium burial origin. The diagenetic evolution sequence from the penecontemporaneous period to the middle–deep burial period in the study area is penecontemporaneous dolomite, anhydrite dissolution → seepage silt filling, freshwater dolomite, calcite, and gypsum filling, pressure solution compaction, calcite partial dissolution → gypsum filling, karst cave, buried hydrothermal dolomite, dolomite partial dissolution → calcite complete dissolution, pore dissolution expansion, and quartz pyrite filling. In the early stage of compaction and pressure solution, the primary pores are rapidly reduced, and in the later stage, sutures are generated to provide channels for reservoir fluid migration. The recrystallization reduces the porosity during the middle–deep burial period. Full article

The Sangu Spring Basin is located in an important economic area, and groundwater is the main source of water for local life and industry. Understanding the sources of chemical components in groundwater is important for the development and utilization of groundwater. In this paper, we analyzed the origin of the chemical components of groundwater and their evolution in the Sangu Spring Basin using statistical analysis, Piper diagrams, Gibbs diagrams, ion ratios, and combined hydrochemistry–isotope analyses. The results show that the groundwater in the Sangu Spring Basin is mainly derived from atmospheric precipitation, that the groundwater in stagnant and confined environment zones was formed under colder climatic conditions, and that the surface water (SW) has a close hydraulic relation with the groundwater. Water–rock interaction is the main factor controlling the composition of groundwater. The compositions of groundwater are mainly derived from carbonate weathering, silicate weathering, and dissolution of gypsum. Na⁺ and K⁺ in groundwater mainly come from the dissolution of albite and potassium feldspar, rather than rock salt. Ion exchange occurs in karst groundwater (KGW) and fissure groundwater (FGW), and ion exchange is dominated by the exchange of Mg²⁺ and Ca²⁺ in the groundwater with Na⁺ and K⁺ in the rock or soil. Sulfate in groundwater is derived from dissolution of gypsum, infiltration of atmospheric precipitation, and leakage of SW. Groundwaters with the highest sulfate content are located in the vicinity of SW, as a result of receiving recharge from SW seepage. Groundwaters with higher sulfate contents are located in the stagnant and deeply buried zones, where sulfate is mainly derived from the dissolution of gypsum. SW seepage recharges groundwater, resulting in increased levels of Cl⁻, NO₃⁻ and SO₄²⁻ in groundwater. These insights can provide assistance in the protection and effective management of groundwater. Full article

The Arabian Desert is characterised by very low rainfall and high evaporation, yet over 210 springs are on its northeastern edge in central Iraq along the Abu Jir lineament, which represents the western depositional margin of a foreland basin infilled by the floodplain sediments of the Tigris and Euphrates Rivers; there is little evidence of faulting. The springs discharge from gently east-dipping Paleocene–Eocene limestones, either where groundwater flowpaths intersect the ground surface or where groundwater flow is forced to the surface by confining aquitards. Calculated annual recharge to the aquifer system across the Arabian Desert plateau (130–500 million m³) is significant, largely due to rapid infiltration through karst dolines, such that karst porosity is the primary enabler of groundwater recharge. The recharge is enough to maintain flow at the Abu Jir springs, but active management of groundwater extraction for agriculture is required for their long-term sustainability. The hydrochemistry of the springs is determined by evaporation, rainfall composition (high SO₄ concentrations are due to the dissolution of wind-blown gypsum in rainfall), and plant uptake of Ca and K (despite the sparse vegetation). Limestone dissolution has relatively little impact; many of the springs are undersaturated with respect to calcite and lack tufa/travertine deposits. The springs at Hit-Kubaysa contain tar and high levels of H₂S that probably seeped upwards along subvertical faults from underlying oil reservoirs; this is the only location along the Abu Jir lineament where deep-seated faults penetrate to the surface. The presence of hydrocarbons reduces the Hit-Kubaysa spring water and converts the dissolved SO₄ to H₂S. Full article

Jinan, renowned as the “Spring City” in China, relies significantly on karst groundwater as an indispensable resource for socio-economic development, playing a crucial role in ecological regulation, tourism, and historical and cultural aspects. The Yufu River basin, situated within Jinan’s karst region, represents a vital riverine leakage zone. Therefore, investigating the evolutionary characteristics and causative mechanisms of surface water and groundwater at different aquifer levels in the Yufu River basin can provide a scientific foundation for the protection of Jinan’s springs. This study, based on hydrogeochemical and isotopic data from the river water, shallow groundwater, deep groundwater, and springs in the Yufu River basin, explored the hydrogeochemical evolution in this region. The findings revealed significant spatial variations in the hydrochemical parameters of the Yufu River basin. Groundwater received contributions from surface water, while springs represented a mixture from both surface water and various recharge aquifers. Dominant ions include Ca²⁺ and HCO₃⁻, with prevailing hydrochemical types being HCO₃·SO₄-Ca and HCO₃-Ca. Atmospheric precipitation served as the primary source of recharge for surface water and groundwater in the Yufu River basin, albeit influenced by pronounced evaporation processes. The hydrochemical composition in the Yufu River basin was primarily attributed to water–rock interactions, mainly driven by the combined effects of carbonate rock, silicate rock, and gypsum weathering and dissolution. Among these, the weathering and dissolution of carbonate rocks played a dominant role, with human activities exerting a relatively minor influence on the hydrochemistry of the Yufu River basin. Full article

This study investigates the processes leading to karst development in the southeastern part of Riyadh city extending up to Al Kharj. Numerous solution features such as sinkholes, collapsed dolines, and solution caverns are common in the area. The role of water in the development of the karst features was investigated using an integrated geological and hydrochemical approach. Geological investigations included the petrographic analysis of rock samples collected from zones of intense karstification with special emphasis on mineral dissolution. The study showed that the Sulaiy Formation is commonly fractured, brecciated, foliated, and contains numerous cavities, vugs, and openings. These features have formed by mineral dissolution by circulating groundwater, which has removed anhydrite beds from the underlying Arab–Hith sequence. Karstification likely started from the tectonically weak zones when there was more groundwater recharge. Studies show that during the early to mid-Holocene period, the climate in the Arabian Peninsula was humid, promoting groundwater recharge and subsequent mineral dissolution, though the process of karstification must have started much earlier. Hydrochemical findings reveal that mineral dissolution (halite and calcium sulfate) is the main process affecting groundwater chemistry. The Piper plot revealed two main hydrochemical facies: the (Ca²⁺ + Mg²⁺)–(Cl+ SO₄²⁻) Type (Type A) and the (Na⁺ + K⁺)–(SO₄²⁻ + Cl) Type (Type B). Most of the samples belong to Type B, typical of groundwater facies affected by dissolution of halite and anhydrite mineral. The absence of the (Ca²⁺ + Mg²⁺)–(CO₃²⁻ + HCO₃⁻) type of groundwater facies indicates a lack of recent groundwater recharge and the removal of carbonate minerals from the system through precipitation, as evidenced by the saturation indices. Plots of the major ionic pairs (cations vs. anions) in groundwater indicate strong halite and gypsum/anhydrite dissolution. Of the three carbonate minerals, calcite has the highest average saturation index followed by aragonite and dolomite. This suggests significant past rock–water interaction leading to carbonate dissolution. Presently, any additional calcium or carbonate ions introduced into the water lead to calcite precipitation. The study indicates that the process of karst development may not be active today. Currently, groundwater chemistry is mainly influenced by rock–water interaction leading to gypsum/anhydrite dissolution, which has resulted in a high concentration of Na⁺, Ca²⁺, Cl⁻ and SO₄²⁻ ions in groundwater. The dissolution of gypsum and halite from the Hith Formation weakens the structural integrity of the overlying Sulaiy Formation, creating large underground cavities. These cavities increase the risk of roof collapse, leading to cover-collapse sinkholes as the roof becomes too thin to support the weight above. Full article

In various areas of the Ebro valley in Spain, including the region discussed here, the risk of sinkholes is becoming particularly severe, particularly impacting urban areas and roadways where land subsidence from karstic processes is common. However, knowledge of the area, its geological–geotechnical configuration, and the carrying out of specific research studies are allowing solutions to be tested in an attempt to resolve these situations. A case in point is the examination of settlement issues along a stretch of the access road leading to the city of Gallur from the east (known as Camino Real) in the Zaragoza province, Spain. Numerous surface manifestations of recent subsidence and/or collapse activities have been observed, manifesting as craters and ground undercuts, some several meters in diameter. The prevalence of highly karstifiable materials in the area, evident from the existence of subsidence pockets and collapse dolines, poses significant safety concerns, particularly for traffic and town access, prompting the closure of Camino Real for several years. Local and provincial authorities have embarked on studies to try to recognise this type of situation. Reports aimed at defining karstification processes, conducting geomechanical analyses of subsidence and cavity collapses, and proposing technical measures to mitigate risks have been prepared. Finally, a consolidation solution was proposed based on injections at column-depth of mortar with special characteristics, combined with the replacement and reinforcement of the most superficial soil by means of high-tensile-strength geotextile meshes. Full article

The hydrogeological conditions of Huainan Coalfield are complex. The Taiyuan formation limestone water (Taihui water) in this area is a direct threat to the water source of the 1# coal mining floor. In order to prevent and control water disasters, Gubei Coal Mine adopted ground high-pressure grouting with fly ash cement to block the hydraulic connection between the Taiyuan formation limestone aquifer and the Ordovician limestone aquifer. However, the injected slurry will destroy the original hydrochemical balance of Taihui water and change its hydrochemical characteristics. Taking the influence area of the 2# karst collapse column in the Beiyi 1# coal mining area of Gubei Coal Mine as an example, a total of 25 Taihui water samples were collected. The hydrochemical characteristics and evolution law of Taihui water before and after grouting are studied via the multivariate statistical method. The research methods include constant index statistics, Piper diagram, correlation analysis, ion combination ratio, and saturation index analysis. The results show that after grouting, the concentrations of Na⁺ + K⁺, Ca²⁺, Mg²⁺, and Cl⁻ in Taihui water decrease, while the concentrations of SO₄²⁻ and HCO₃⁻ increase. The average values of PH and TDS become larger. The hydrochemical types of Taihui water are more concentrated, mainly HCO₃-Na and Cl-Na. The correlations between conventional indicators decrease. According to the analysis of ion combination ratio, dissolution, cation exchange, and pyrite oxidation mainly occur in Taihui water, and these effects are enhanced after grouting. The saturation index results show that after grouting, the saturation index of dolomite, calcite, and gypsum is significantly reduced, and the saturation index of rock salt is slightly increased. The conclusion of this study is that the hydrochemical characteristics of Taihui water are greatly affected by fly ash cement. Moreover, because fly ash cement contains a lower calcium oxide content than ordinary Portland cement, the effect of fly ash cement on the ion concentration of Taihui water and the resulting hydrogeochemical effect are significantly different. Therefore, in the treatment of mine water disasters, the hydrogeochemical evolution law affected by fly ash cement grouting should be identified. Full article

Frequent surface water–groundwater interactions and prevalent anthropogenic inputs make karst water systems vulnerable to human disturbance. As a typical karst region in North China, the Jinan Spring Catchment has become increasingly threatened due to rapid population growth and urban expansion. In this study, the local river–spring interaction and its interference with the hydrogeochemical evolution of groundwater are evaluated based on water stable isotopes and hydrochemistry. Twenty-two karst groundwater, eleven Quaternary pore water, sixteen spring water, and thirty-two surface water samples were collected during low- and high-flow conditions over the course of a year. The isotopic signatures of four different water types display significant differences, reflecting the recharge–discharge relationship of the karst water system. Mountainous springs feature lighter isotopes, whereas urban springs have significantly heavier isotopes. The result of end-member mixing analysis shows that the surface–groundwater interaction varies spatially and temporally within the spring catchment. Urban springs receive considerable replenishment from the surface water, especially after rainy episodes (up to 50%), while mountainous springs show little hydraulic dependence on surface water leakage (4~6%). Local mineral dissolution (including calcite, dolomite, gypsum, and halite), CO₂ dissolution/exsolution, and cation exchange are the main hydrogeochemical processes constraining water chemistry in the spring catchment. The deterioration of water quality can be attributed to anthropogenic influences involving the discharge of domestic effluents, agricultural activities, and irrigation return flow. The findings of this work can improve our understanding of the complex karst water system and serve as a reference for sustainable groundwater management in other karst areas of northern China. Full article

The geochemical characterization and evolution of shallow groundwater in the Zihe River source area is a key issue that needs to be addressed. In this study, a combination of traditional geochemical techniques and geochemical modeling was used to explain the geochemical processes and major ion sources in the chemical evolution of shallow groundwater in the Zihe River source area, Northeast China. Fifty-seven water samples were collected in June 2020 for chemical analysis, and the results showed that the main groundwater chemistry types in the three major aquifers are HCO₃·SO₄-Ca_·Mg-type pore water from loose quaternary rocks, HCO₃·SO₄-Ca_·Mg-type karstic fissure water from carbonate rocks, and HCO₃·SO₄-Ca-type weathered fissure water from massive rocks. Water–rock interactions in alkaline environments were the main causes of changes in groundwater chemistry. Rock weathering dominated the geochemical evolution of each aquifer. The analysis of ion concentration ratios and modeling revealed that the aquifer’s chemical components are mainly derived from the dissolution of dolomite and calcite and partly from the infiltration of pollutants containing ${\mathrm{C}\mathrm{l}}^{-}$ and ${\mathrm{N}\mathrm{O}}_3^{-}$, as well as from the dissolution of quartz. Mg²⁺ is derived from the dissolution of dolomite. ${\mathrm{H}\mathrm{C}\mathrm{O}}_3^{-}$ is primarily derived from the co-dissolution of calcite and dolomite, and to a lesser extent, its content is also influenced by the recharge of rainfall. ${\mathrm{S}\mathrm{O}}_4^{2-}$ has two sources: it mainly originates from the dissolution of gypsum and the anhydrite layer, followed by atmospheric precipitation. The synthesis showed that the groundwater quality in the source area of Zihe River is good, all the indices reached the standard of class III groundwater quality, and the overall degree of human pollution is low. The results of this research will provide a scientific basis for the local authorities to delineate karst groundwater protection zones in the Zihe River source area and to formulate resource management strategies for the development, utilization, and protection of karst groundwater. Full article