The characteristics and stages of collapse–filling in paleo-underground rivers vary in recharge–runoff–discharge zones, constraining the associated fracture-caved reservoirs in carbonate strata. This paper comprehensively uses core, fluid inclusion, and carbon–oxygen isotope to probe the evolution process and migration of collapse–filling in paleo-underground rivers in the Northern Uplift of the Tarim Basin. The results show that 1) more than three stages of collapse–filling were identified in recharge–runoff–discharge zones, and a four-stage differential collapse–filling process was proposed to summarize the evolution of paleo-underground rivers. 2) The collapse–filling process varies spatiotemporally in the recharge, runoff, and discharge zones. Hydrodynamic strength and filling capacity migrate gradually from the recharge zone to the discharge zone. 3) Collapse–filling mechanisms, including gravity, suffusion, and suction–erosion mechanisms, also vary along with the collapse–filling evolution process of paleo-underground rivers. The research provided a new insight to recognize and interpret the differential planar distribution and vertical filling of the paleo-underground river system, which can be further applied to investigate the fracture-caved karst reservoirs.

Karst fracture-cavity of Ordovician Yingshan Formation is the main carbonate reservoir in Tahe oilfield. The development of karst fracture-cavity shows strong heterogeneity. The complex diversification of filling types, types of filling materials and filling characteristics leads to the complexity of karst fracture-cavity reservoirs, which has a direct impact on the development of oil reservoirs. Understanding the characteristics of karst fracture-cavity filling is conducive to finding the optimal reservoir, which is of great significance to the study of petroleum geology in this area. In this study, the Ordovician Yingshan Formation cores from several wells in Tahe oilfield were observed, and the karst fracture-cavity fillings and limestone bedrock of typical drilling of Yingshan Formation were collected. Combined with the characteristics of fracture-cavity filling, the carbon and oxygen isotope characteristics are analyzed, and the sedimentary paleoenvironment is clarified, which provides a new geochemical basis for inversion of reservoir formation process. Based on the core observation, description and filling type statistics of 31 drillings in Tahe oilfield, it is found that the fillings of karst fracture-caves of Ordovician Yingshan Formation in Tahe area are mainly characterized by mechanical fillings and chemical deposits, followed by slump fillings. The slump fillings mainly filling in caves and seven boreholes—A8, T615, T502, S64, S70, T403 and T624—can show the most typical characteristics. We collected 35 filling samples of the karst fracture-cavity in these seven typical drillings of Ordovician Yingshan Formation, including calcareous argillaceous, sandy, calcite, breccia and limestone bedrock filled in the dissolution pores. Then, we tested and analyzed δ13C and δ18O of the filling samples. The results show that the variation range of carbon and oxygen isotopes of the backfill is large, with δ13C from 0.75 ‰ to −10.14 ‰ and δ18O from −5.94 ‰ to −14.14 ‰. Compared with the carbon and oxygen isotope of bedrock, the values of δ13C and δ18O of 80% of the backfill are negative, and the calcite is the most negative. The values of δ13C and δ18O of calcium mud filling were significantly positive. There are four different types of formation environment for karst fracture-cavity fillings in Ordovician Yingshan Formation. The first type is the contemporaneous or early diagenetic karst environment. The δ13C and δ18O of the karst fracture-cavity fillings are from −2.29‰ to 0.75‰ and from −5.94‰ to −8.57‰, respectively, which are similar to the carbon and oxygen isotope characteristics of the marine limestone of the Yingshan Formation. This finding indicates that the fracture-cavity fillings are formed in the contemporaneous or early diagenetic marine karst environment, which may be the result of the joint filling of mud carried by flowing water and carbonate rock deposition in the contemporaneous karst period. The second type is Late Caledonian-Early Hercynian weathering crust karst, with the most obvious negative values of carbon and oxygen isotopes: δ13C from −10.14‰ to −8.57 ‰, and δ18O from −14.14‰ to −13.44 ‰, respectively. The negative δ18O value is mainly caused by the low δ18O value of atmospheric freshwater, which leads to the negative δ18O value of precipitated calcite. There are two main reasons for the negative δ13C value. One is the exposure environment of late Caledonian-early Hercynian affected by low δ13C CO2 in atmospheric fresh water, and the negative δ13C value of calcite precipitated after reaction with carbonate rocks. The other is that the content of organic matter overlying on the weathering crust in the Silurian clastic strata is high, and the δ13C value is low due to the oxidation of CH4 by organic matter. The third type is buried karst environment. Both the negative values of δ13C (from −6.54‰ to −3.07‰) and δ18O (from −13.11‰ to −12.43‰) indicate that the fillings are affected by different degrees of atmospheric freshwater in buried karst environment. The fourth type is the late to modern karst environment. The values of δ13C (from −5.24‰ to −0.79‰) and δ18O (from −11.15‰ to −8.77‰) are quite different from those of the carbon and oxygen isotopes in terms of bedrock background values. Most of the filling materials are calcareous argillaceous mechanical filling, mainly filling in karst caves and dissolved structural joints. The filling process is slow and long, and is affected by organic matter to varying degrees. Karst fracture-cavity filling are the product of the formation of karst reservoir in the transformation process. The analysis of carbon and oxygen isotopes of carbonate rocks and karst fracture-cavity fillings is one of the important means for the study of paleokarst oil and gas reservoirs. It is helpful to understand the formation environment, development and evolution of karst and its relationship with the development of oil and gas reservoirs, which is of great significance for the prediction of karst reservoirs and oil and gas exploration.

[研究目的]由于人类活动的影响,地下水硝酸盐(NO3-)污染越来越严重.[研究方法]利用水化学和硝酸盐氮氧同位素(δ15NNO3与δ18ONO3)研究云南昭通盆地地下水NO3-来源与转化过程,用SIAR模型定量计算泉水和民井中不同NO3?来源的比例.[研究结果]结果表明:(1)研究区钻孔水水质良好,但19％的泉水NO3?超过生活饮用水标准限值,13％的民井因NO3?超标而不适宜灌溉;(2)泉水和民井中δ15NNO3值分别介于2.4‰～18‰和?4.5‰～39.7‰,平均值为7.9‰和17.3‰,δ18ONO3值介于?8.8‰～39.3‰和?16.4‰～26.7‰,平均值为2.5‰和0‰,同位素组成和水化学指示硝化作用主导着研究区氮循环;(3)粪肥污水、土壤氮和铵态氮肥料是地下水中NO3-主要来源,其对泉水的NO3-平均贡献率分别为48％、28％和24％,对民井的NO3-平均贡献率分别为87％、6％和7％.[结论]居住区和耕地区地下水中NO3-的粪肥污水源分别高达89％和72％,林地地下水仅为27％,表明受人类活动影响越强烈的地区地下水NO3-污染越严重.

In recent years, deep karst caves are commonly met in deep resource exploration and engineering construction. However, the deep-buried caves lead to the insufficient research on the genesis and development mechanism of deep karst caves. As good research samples, a large amount of complete drilling cores in deep karst caves are founded in Huanjiang sag in Guangxi. The karst morphology analysis of the drilling core in Well HD1-4 reveals that the deep karst in Huanjiang area is mainly composed of net cracks and holes expanding along cracks and dolomite honeycomb pores, and large karst caves are also developed, with the maximum height of 20 m. The types of fillings in deep karst caves are diverse. Through the observation of the whole well core, it is found that the deep karst cave fillings are of four characteristics. (1) Calcification growth,the mixed growth pattern of chemical and argillaceous substances reflects periodic growth in the cave, which may be associated with surface hydrological systems. (2) Flower-like growth pattern,white calcite with multi-stage growth can be identified in pores, but the growth direction and growth environment of each stage are different, hence forming flower-like growth pattern. (3) Primary chemical fillings of the hole,the hole is filled with calcite or dolomite, and the crystal form of calcite in part of the hole is good. (4) Argillaceous fillings in the cave, argillaceous fillings can be seen at 230 m, 432 m, 880 m and even 1,132 m in Well Huandi 1-4, which are far lower than the local discharge datum or the sea level. These argillaceous fillings may come from the surface mud seepage along the fracture or the mud beneath the ancient exposed surface. In this paper, the carbon and oxygen isotope analyses of deep karst cave fillings and surface karst cave fillings in Well HD1-4 drilling show the wide distribution of carbon and oxygen isotope of deep karst fracture. δ13C values are between −5.2‰ and −2‰ with the average value of −0.33‰. δ18O values are between −16.78‰ and −5.3‰ wtih the average value of −11.45‰. The values show the general negative skewness. The negative skewness of carbon and oxygen isotope of calcite fillings in the pores is the largest, and that of dolomite is the smallest. The carbon and oxygen isotope values of calcareous mudstone are the closest to those of modern atmospheric freshwater.Based on the analysis of geological conditions, four large-scale paleokarst processes and filling periods are founded in the formation and filling stages of deep karst in the Huanjiang area. (1) In the karst environment in contemporaneous period and penecontemporaneous peiord, the distribution range of δ18O is the same as the background value of the bedrock of carbonate rock, but δ13C changes greatly. The results show that the karst environment is similar to the sedimentary environment of carbonate rocks, which reflects the short-term exposure of karst after the deposition of carbonate rocks in the contemporaneous period, and the filling shows the characteristics of early precipitation. Karst space is mainly characterized by dissolution pores, which provides the basis for further karst development. (2) The karst environment of atmospheric fresh water in the hypergene period is affected by atmospheric fresh water δ13C, and the δ18O value shows a significant negative skewness. The fact that δ13C is less than −2.5‰ and δ18O is between −13 and −8.2‰ indicates the karst environment is an open system, and a large number of argillaceous substances infiltrate with surface water and fill karst caves, making a certain impact on the preservation of deep resources. (3) In the shallow-buried karst environment, the δ18O value of the filling is negative, which is more negatively skewed than that of Type I bedrock. The δ13C value is basically consistent with the bedrock value, and there is no obvious negative skewness. The δ13C value is between −2.0‰ and 2.5‰, and the δ18O is between −13.0‰ and −9.0‰. Due to the increase of temperature and pressure in the closed system during the burial peirod, there gradually precipitates and forms dolomite. (4) In the deep-buried or hydrothermal karst environment, the δ18O value of fillings is obviously negative, and high-temperature fluid flows up along the fault to form the karst dissolution space which becomes the reservoir place of various deposits. The hydrothermal karst with high temperature and the atmospheric freshwater karst are the main periods of the formation of deep karst fracture-cavity filling in Huanjiang area. The research results are of great significance for deep karst reservoir prediction and deep resource exploration in the later stage.

The nitrate (NO3- ) contamination of karst aquifers as an important drinking water reservoir is increasing globally. Understanding the behavior of nitrogen (N) in karst aquifers is imperative for effective groundwater quality management. This study combined multiple stable isotopes (82H-H2O, 818O-H2O, 813C-DIC, 815N-NO3, and 818O-NO3), including hydro-chemical data, with a tracer test and a Bayesian isotope mixing (SIAR) model to elucidate the NO3- sources and N cycling within the Babu karst aquifer in Guizhou Province, Southwest China. Nitrate isotopes and SIAR model revealed that manure and sewage, nitrogen fertilizer, and soil organic nitrogen were the three dominant NO3- sources in winter, contributing to 37%, 32%, and 31% to spring NO3-, and 38%, 31%, and 31% to surface water NO3-, respectively. The 818O-NO3 values of sampled waters ranging from 0.3%o to 13.7%o (mean of 7.7 +/- 3.0%o; N = 63) and the significant negative correlations between 815N-NO3 and 813CDIC in the spring waters (P < 0.01) revealed that nitrification was the primary N transformation process in the Babu watershed. Whereas, denitrification might still occur locally, confirmed by the enriched values of 815N-NO3 (14.3 +/- 7.6%o; N = 6) and high denitrification extent (46.6 +/- 22.2%; N = 6) in the springs from residential areas, and by elevated 813C-DIC (-11.2 +/- 0.6%o; N = 26) and 815N-NO3 values (18.9 +/- 5.2%o; N = 26) in the boreholes. During the base flow period, point-inputs of the AMD-impacted stream and sewage waters, and short transit time (<5 days) were conducive to nitrification processes in the karst conduit, resulting in elevated NO3- concentration and NO3-/Cl- ratio at the watershed outlet. Approximately 50% of NO3- flux at the outlet was derived from nitrification, indicating that a significant extent of nitrification occurred in the NH4+-contaminated karst conduit, which may be a new NO3- source to receiving rivers and lakes. This study provided an integrated method for exploring the N dynamics in contaminated karst aquifers. Moreover, the study highlighted that the point N sources control required particular attention for groundwater protection and restoration.

会仙喀斯特湿地分布于漓江流域和柳江流域的分水岭地带.该湿地仅由地下水补给,地下水水位对维持该湿地生态系统起着决定性的作用.2019年,在会仙湿地具有代表性的6个水位观测点(4个地下水水位观测点,2个地表水水位观测点),利用压力传导型水位计,自动记录了一个水文年的地下水和地表水水位.研究结果表明,雨季与枯季会仙湿地的地下水水位存在明显差异,地下水水位的变化幅度最大可达2.5 m;核心区的地下水分水岭具有可移动性,在雨季降水量增加时,其向东移动,在雨季降水量减小和枯季水位下降时,其向西移动;暴雨过后,地下水和地表水水位都迅速回落至暴雨前的水平,地表水体和会仙湿地地下水系统都没有起到储蓄洪水的作用;枯水期地下水水位继续下降,并且低于149 m,导致枯水期会仙湿地严重萎缩;在枯水期,通过外部输水补给,保持会仙湿地的地下水水位不低于149 m,是减缓该湿地退化的关键措施.

Hypogene karst is a special manifestation of karst development in spatial scale. Intensive study of its development mechanism has significant meaning for engineering construction, shale gas and geothermal exploitation. To reveal the developing pattern of hypogene karst in Huanjiang syncline, karst groundwater at different depths in wells HD1-2 and HD1-4 and karst springs was selected as the research object. Through the analysis of geochemistry and stable isotopes of karst groundwater, it was revealed that the circulation pattern of deep karst water came from the common recharge of meteoric water and fossil water hosted in karst caves, runoff of deep faulting belts and discharge of large karst springs, over Huanjiang syncline, which provides good hydrodynamic conditions for hypogene karst development. Meanwhile, the widely developed faulting belts and structural fissures provide primitive dissolution space. Through the above analysis, the paper constructs a hypogene karst development pattern controlled by the deep cycle of groundwater in Huanjiang syncline.

Multiple isotopes (C, N, and O) and hydrochemical data were used to trace the sources and fate of nitrate in ground and surface waters of the Babu subterranean stream watershed in Guizhou Province. The origin of nitrate in the water samples was also quantitatively analyzed by the SIAR model. Approximately 38% of the groundwater samples were not drinkable because the nitrate exceeded the drinking water standard, thereby indicating that the groundwater was seriously polluted by nitrate. The ranges of δ15N-NO3, δ18O-NO3, and δ18O-H2O in groundwater were 2.30‰-30.33‰ (mean of 9.68‰), 2.65‰-13.73‰ (mean of 6.64‰), and -8.83‰﹣-7.37‰ (mean of -8.18‰), respectively. Based on the stable isotopic compositions (δ15N-NO3, δ18O-NO3, and δ18O-H2O), nitrification was the dominant process in the basin. The nitric acid produced by nitrification promoted the dissolution of carbonate rocks, thereby leading to a significantly negative correlation (P<0.001) between the carbon isotope of dissolved inorganic carbon (δ13CDIC) and δ15N-NO3 and indicating that δ13CDIC, combined with δ15N-NO3, is effective in exploring the fate of nitrate in karst groundwater. The nitrate in the ground and surface waters mainly originated from soil N, manure and sewage, and ammonium nitrogen fertilizer. The results of the SIAR model showed that the contributions of soil N, manure and sewage, and ammonium nitrogen fertilizer were 36.19%, 33.71%, and 30.10% in groundwater, respectively, and 39.15%, 36.08%, and 24.77% in surface water, respectively. Therefore, it would be more effective to reduce the nitrate recharge flux in groundwater by simultaneously removing nitrate and ammonium nitrogen during wastewater treatment and by adopting scientific fertilization technology in agricultural areas.

Karst water, which provides approximately 25% of the world's drinking water, is especially vulnerable to anthropogenic pollutants. To determine the variations between high and low flow periods and the sources of dissolved sulfate (SO42-) in small karst basins, SO42- concentrations, stable sulfur and oxygen isotopes (δ34S-SO4 and δ18O-SO4), and oxygen isotopes of water (δ18O-H2O) were investigated in surface and groundwaters, during the high and low flow seasons, within the Babu subterranean stream basin. Analysis showed that: ① the water samples that were directly impacted by acid mine drainage exhibited high SO42- concentrations (≥250 mg·L-1) and significant seasonal variation, while the seasonal variation of non-AMD-impacted water with low SO42- concentrations was not significant. ② During the high flow season, the mean δ34S-SO4 and δ18O-SO4 values of surface water were -10.5‰ and 4.7‰, respectively, and -11.5‰ and 1.3‰ during the low flow period; the mean values of δ34S-SO4 and δ18O-SO4 in groundwater samples were -2.9‰ and 7.1‰ during the high flow period, respectively, and -3.2‰ and 6.2‰ during the low flow period. Both surface and groundwater samples exhibited higher δ34S-SO4 and δ18O-SO4 values during the high flow period than during the low flow period. ③ The values of δ34S-SO4 in the surface and groundwater samples were relatively stable, indicating that the sources of SO42- at specific sampling sites were stable.④ The main sources of SO42- in surface and groundwaters were rain, sulfide, and gypsum, accounting for 13%, 40%, and 47%, respectively, of SO42- in samples taken from the basin outlet during the high flow season, and 18%, 39%, and 43%, respectively, in samples obtained during the low flow season.

The pollution of karst aquifers by acid mine drainage (AMD) waters is increasing. Major and minor ions (Ca2+, Mg2+, HCO3−, SO42−, F−, and Fe), stable sulfur and oxygen isotopes of dissolved sulfates (δ34SSO4 and δ18OSO4) and oxygen isotope of water (δ18OH2O), were analyzed in rainwater, surface water, groundwater, and AMD water sampled from the Babu subterranean stream watershed, in Southwest China. The principal aim of this study was to explore the impact of AMD waters on the evolution of karst aquifers. Based on hydrogeochemistry and stable isotopes (δ18OH2O, δ18OSO4 and δ34SSO4): (1) the chemistry of AMD waters was primarily controlled by pyrite oxidation, karst conduit water by AMD waters and mixing with calcite and dolomite dissolution, and spring water by atmospheric precipitation and carbonate dissolution; (2) contamination of the karst conduit water was mainly attributed to the input of AMD waters, resulting in a shift of δ34SSO4 towards more negative values (from 3.4‰ to −13.2‰); (3) the quality of karst conduit water changed from suitable to unsuitable for irrigation and drinking, particularly due to the increase in total Fe, SO42−, and F− concentrations, reflecting the cumulative effect of AMD waters derived from tailings dumps; this influence was enhanced during rainstorm/drought and anthropogenic activities; and (4) the flow of contaminated groundwater through the conduit promoted the dissolution of carbonates, especially during the dry season due to the greater proportion of AMD in the groundwater. This released more CO2 to the atmosphere. We believe that analysis of stable isotopes (δ18OH2O, δ18OSO4, and δ34SSO4), combined with hydrogeochemistry, is effective for exploring the impact of AMD on karst aquifers. Therefore, reasonable treatment methods should be taken to reduce the negative impacts of tailings dumps on karst aquifers.

Based on the seasonal characteristics of groundwater hydrochemistry and the carbon isotopes (δ13C) of dissolved inorganic carbon (DIC) in the Hongjiadu Basin, Guizhou Province, this paper discusses the natural processes and anthropogenic factors affecting the characteristics of δ13CDIC in karst groundwaters under different land use types. The results show that the main sources of DIC in groundwater are carbonate weathering and soil CO2. In winter, the δ13CDIC values for groundwater ranged from -14.8‰ to -4.1‰ with an average of -10.1‰ and, in summer, ranged from -14.5‰ to -6.3‰ with an average of -10.2‰. Sulfuric acid from sulfide oxidation in coal-bearing strata and acid rain is involved in carbonate weathering, resulting in the enrichment of groundwater with heavy carbon isotopes. Due to the soil CO2 effect, the δ13CDIC values of woodland groundwater experiencing less disturbance from human activities are lower in summer than in winter. The degradation of organic matter input from residential areas is a significant contributor of DIC to groundwater. The average values of δ13CDIC in winter and summer were -11.9‰ and -11.6‰, respectively, and the seasonal difference was relatively small in residential areas. During different seasons and for different types of land use, human activities could lead to differences in groundwater δ13CDIC values and hydrochemistry. Therefore, δ13CDIC can reflect the impact of human activities on karst aquifers, which has important ecological significance.

泉水是洪家渡盆地居民的重要饮用水源,近些年随着人类活动的增强,泉水水质呈恶化趋势.为查明泉水中污染物来源及其地球化学过程,采集15组具有代表性的水样分析水化学、溶解无机碳(dissolved inorganic carbon,DIC)碳同位素(δ13CDIC)特征.结果 显示泉水组分以Ca2、Mg2和HCO3为主,富集SO42--,硫酸、硝酸与碳酸共同参与了研究区碳酸盐岩风化.泉水Na+、Cl、K+和NO3-主要来源于肥料(如化肥、粪肥)和污水,SO42--主要来源于煤层中硫化物氧化、雨水和污水.S01和S09泉因NO3-超标已不可直接饮用.泉水δ13CDIC值主要受碳酸盐岩溶解和土壤CO2的控制,但硫酸、硝酸参与碳酸盐岩风化使泉水δ13CDIC值偏正,且SO42-、NO3-浓度上升;而硫酸盐细菌还原作用和反硝化作用及人为输入污染物中有机质的降解导致泉水δ13CDIC值偏负.诸多因素导致泉水δ13CDIC值在-17.72‰～-8.74‰之间,平均值为-11.58‰.研究证实δ13CDIC与水化学相结合是探讨碳的生物地球化学过程及示踪岩溶区地下水污染物来源行之有效的方法.

为确定会仙岩溶湿地不同介质中抗生素的污染特征及来源,利用液相色谱串联质谱联用仪分析了磺胺类(SAs)、氟喹诺酮类(FQs)和四环素类(TCs)三大类20种抗生素的含量.结果表明,研究区内水土介质监测的抗生素中共检出12种,检出浓度范围为n.d～106 ng· L-1,其中,甲氧苄氨嘧啶(TMP)的浓度最高.各环境介质中,以养殖用水和地表河水中检出的抗生素种类相对较多,分别为10种和8种,溶潭水和土壤中则检出的抗生素种类较少.因子分析结果显示,会仙湿地水体中的典型抗生素来源可归为两类,一类以受外源污染为主,从而导致地表河水中磺胺氯达嗪(SCP)、磺胺嘧啶(SDZ)、磺胺甲恶唑(SMZ)、诺氟沙星(NOR)、氧氟沙星(OFL)检出浓度较高,一类受湿地内养殖污染,从而造成水土介质中磺胺二甲基嘧啶(SMD)、甲氧苄氨嘧啶(TMP)和金霉素(CTC)检出.水体中检出的抗生素主要受溶解氧(DO)影响,此外,甲氧苄氨嘧啶(TMP)、恩诺沙星(ENR)和强力霉素(DOX)与NH4+存在一定的协同污染关系.风险评估结果表明,恩诺沙星(ENR)处于高风险的范围内,磺胺甲恶唑(SMZ)、诺氟沙星(NOR)和氧氟沙星(OFL)处于中等风险,中等风险的抗生素主要集中在地表河水中,高风险抗生素则在养殖用水中.整体来看,研究区水体中抗生素存在一定的风险.因此,针对这一现象应减少存在生态风险抗生素的使用,并对有潜在风险的抗生素加以防范.

研究湖南新田富锶地下水水化学特征及成因,为富锶地下水的可持续利用与开发提供理论依据.对研究区21个下降泉、30个机井富锶地下水样品的水化学类型、化学成分含量特征、成分间相关性以及离子比值的研究.结果表明:下降泉水化学类型全部为HCO3-Ca型,机井水化学类型以HCO3-Ca、HCO3-Ca·Mg型为主.相关分析表明,下降泉和机井中SO42-与Ca2+、Mg2+均表现显著相关或极显著相关,HCO3-与Ca2+、SO42-与NO3-在下降泉与机井中的相关性具有差异,下降泉、机井Sr与Ca2+、Mg2+、HCO3-均表现为极显著相关.Gibbs图表明下降泉和机井的水化学组成主要受水-岩相互作用的控制,下降泉、机井c(Ca2+)/c(Mg2+)、c(HCO3-)/c(SO42-+Cl-)、c(Na+)/c(Cl-)、c(Cl-)/c(Ca2-)系数比值具有差异.结果表明富Sr地下水的形成受碳酸盐岩成分影响显著,赋存条件的差异导致富锶地下水在下降泉、机井中的水化学特征、相关性以及离子系数比值的差异.