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1.
 Chemical composition of water inflows in the Zakrzówek quarry, developed in fractured and karstified Upper Jurassic limestones, is controlled by infiltration of polluted water from the Vistula River and by infiltrating meteoric water. The river water TDS value is 2.5 g/dm3. The quarry waters have 0.6–2.0 g/dm3 TDS. Highly mineralised waters belong to Cl-Na type. With decreasing TDS the percentage of sulphates, calcium, magnesium and hydrocarbonates increases. This seems to result from various processes including dilution of polluted river water, leaching of aquifer rocks, and ion exchange. The transfer time of river water to the quarry is about 100–120 days. Concentration of contaminants contained in the river water declines during the migration through limestones to the quarry. Received: 7 March 1997 · Accepted: 7 December 1998  相似文献   

2.
 The Aachen hot springs flow out from Upper Devonian limestones at the Variscan thrust front of the Rhenish Massif. Hydrogeochemical analyses were used to determine the origin of the water and show that sodium, chloride, and sulfate originate from dissolving evaporites that are influenced by meteoric groundwater. The circulation depths of the Aachen thermal water is estimated to be >3500 m using SiO2–geothermometry and the regional geothermal gradient of about 30  °C/km. The deep circulation in Paleozoic sandstones, siltstones and shales and a considerable residence time allow rock water reactions which explain the concentrations of Ba, Sr, F and Si. While the thermal water rises into Upper Devonian limestones carbonates are dissolved. Cooler fresh water from the vicinity contributes to the thermal aquifer depending on the pressure head of the springs. Sulfate reduction coupled with methane oxidation can be observed as soon as the water temperature is below 65  °C. Received: 21 September 1998 · Accepted: 19 May 1999  相似文献   

3.
 A strong geochemical gradient was observed in the thick overburden aquifer of the Asa drainage basin. Different types of groundwater occur at different (downslope) locations and groundwater table depths. The following sequence was noticed with increasing distance downslope or with increasing groundwater table depth: 1. Ca–Mg–HCO3 water at about 390-m groundwater table elevations or upslope locations. 2. Ca–Mg–HCO3–Cl water at middle-slope locations or groundwater table elevations of about 350 m above sea level; 3. Ca–Mg–SO4–Cl water at downslope locations or groundwater table elevations of about 300 m above sea level. In this basin, changes in the type of water are expected at about every 40–50 m depth from the surface. Statistical analysis via the determination of the correlation coefficient (r) and regression analysis shows that about 80–99% of the variation in groundwater chemistry is accounted for by the topography, using the model presented in this paper. The rate of change in the sequence will depend on the permeability of the aquifer, which determines the rate of groundwater flow and the residence time, and the nature of recharge. Received: 4 February 1997 · Accepted: 22 July 1997  相似文献   

4.
 The aim of the study is to investigate the interaction between waters of Lake Girdev and groundwater in the allochthonous limestone units exposed in the area between Lake Girdev and Kazanpınarı Spring, southwestern Turkey. The features analyzed include the flow direction and apparent groundwater velocity, their relationship with Lake Girdev, and the effect of lithological and structural features on the groundwater circulation. The results of a fluorescein tracer test indicate that groundwater flows east-northeast and the apparent flow velocity ranges from 26.2 to 35.6 m h–1 between the injection site and various observation points. Tritium data suggest that the water of Lake Girdev and groundwater are probably similar in age, and oxygen-18 isotope data indicate that water derived from Lake Girdev is the main source of recharge to the aquifer. The aquifer is fed not only by Lake Girdev but also by rainfall percolating through allochthonous limestones; together, these provide the discharge of springs in Elmalı Polje. The permeability of the allochthonous limestone aquifer has been enhanced as a result of jointing and faulting. Received, June 1997 / Revised, June 1998, March 1999 / Accepted, July 1999  相似文献   

5.
 This paper presents hydrogeological problems occurring during municipal water exploitation and mine dewatering. These activities result in groundwater quantity and quality changes in the fissure-karstic aquifer. Increase of nitrate concentration up to 12 mg NNO3/l due to intensive fertilizer use, and high tritium concentration, show water system impact up to 100 m depth. Intensive water exploitation produces large cones of depression with over 40-m water-level depletion in the Opole region. Flow rates of major components and isotopes have been verified by chemical migration history. Some aspects of the protection policy of this type of aquifer are also discussed. Received: 7 March 1997 · Accepted: 17 November 1998  相似文献   

6.
A hydrochemical investigation was conducted in the Ejina Basin to identify the hydrochemical characteristics and the salinity of groundwater. The results indicate that groundwater in the area is brackish and are significantly zonation in salinity and water types from the recharge area to the discharge area. The ionic ration plot and saturation index (SI) calculation suggest that the silicate rock weathering and evaporation deposition are the dominant processes that determine the major ionic composition in the study area. Most of the stable isotope δ18O and δD compositions in the groundwater is a meteoric water feature, indicating that the groundwater mainly sources from meteoric water and most groundwater undergoes a long history of evaporation. Based on radioactive isotope tritium (3H) analysis, the groundwater ages were approximately estimated in different aquifers. The groundwater age ranges from less than 5 years, between 5 years and 50 years, and more than 50 years. Within 1 km of the river water influence zone, the groundwater recharges from recent Heihe river water and the groundwater age is about less than 5 years in shallow aquifer. From 1 km to 10 km of the river water influence zone, the groundwater sources from the mixture waters and the groundwater age is between 5 years and 50 years in shallow aquifer. The groundwater age is more than 50 years in deep confined aquifer.  相似文献   

7.
 The Hadejia–Nguru Wetlands are annually inundated flood plains in semi-arid northeastern Nigeria. The area has a unique ecosystem that forms a natural barrier against the encroachment of the Sahara desert. Both the rich wetland vegetation and local farmers using shallow tube wells depend on a groundwater mound (with a water table less than 6 m below the surface) that is present in the unconfined aquifer under the flood-plain area. Using well records (1991–97) and a hydrogeologic profile based on piezometers that were monitored for two years, it is shown that recharge through the annually inundated flood plains is the source of the groundwater mound. Maintenance of the groundwater-recharge function of the flood plains depends on wet-season releases from two large upstream dams. On the basis of a water-budget method, the mean (1991–97) wet-season unconfined groundwater recharge in the flood-plain area between Hadejia and Nguru and in the immediate vicinity (1250 km2) is estimated to be 132 mm (range, 73–197 mm). Outflow from the unconfined flood-plain aquifer to the unconfined upland aquifer is approximately 10% of the wet-season flood-plain recharge. The unconfined groundwater outflow from the flood-plain area can provide a significant contribution to the present-day rural water supply in the surrounding uplands, but it does not offer much potential for additional groundwater abstraction. In addition to outflow to the upland aquifer (∼14 mm), the distribution of the annually recharged water volume of the shallow flood-plain aquifer is (1) domestic uses (3 mm), (2) small-scale irrigation (∼15 mm), and (3) evapotranspiration ( 1 100 mm). Along the hydrogeologic profile, the recharge in the upland (i.e., outflow from the unconfined flood-plain aquifer and possibly diffuse rain-fed recharge) is in balance with the water uses (i.e., domestic uses, groundwater outflow, and evapotranspiration). The absence of a seasonal water-level trend in the two piezometers in the upland indicates that no rain-fed recharge occurs through preferential path-way (macropore) flow. Received, June 1998 / Revised, November 1998, January 1999 / Accepted, January 1999  相似文献   

8.
 The Heretaunga Plains, Hawke's Bay, New Zealand, is underlain by Quaternary fluvial, estuarine-lagoonal, and marine deposits infilling a subsiding syncline. Within the depositional sequence, river-channel gravels form one of the most important aquifer systems in New Zealand. An interconnected unconfined–confined aquifer system contains groundwater recharged from the Ngaruroro River bed at the inland margin of the plain, 20 km from the coast. At the coast, gravel aquifers extend to a depth of 250 m. In 1994–95, 66 Mm3 of high quality groundwater was abstracted for city and rural water supply, agriculture, industry, and horticulture. Use of groundwater, particularly for irrigation, has increased in the last 5 years. Concern as to the sustainability of the groundwater resource led to a research programme (1991–96). This paper presents the results and recommends specific monitoring and research work to refine the groundwater balance, and define and maintain the sustainable yield of the aquifer system. Three critical management factors are identified. These are (1) to ensure maintenance of consistent, unimpeded groundwater recharge from the Ngaruroro River; (2) to specifically monitor groundwater levels and quality at the margins of the aquifer system, where transmissivity is <5000 m2/d and summer groundwater levels indicate that abstraction exceeds recharge; (3) to review groundwater-quality programs to ensure that areas where contamination vulnerability is identified as being highest are covered by regular monitoring. Received, January 1998 / Revised, August 1998, March 1999 / Accepted, April 1999  相似文献   

9.
 Intensive application of surface water in command areas of irrigation projects is creating water logging problems, and the increase of groundwater usage in agriculture, industry and domestic purposes (through indiscriminate sinking of wells) is causing continuous depletion of water levels, drying up of wells and quality problems. Thus the protect aquifers to yield water continuously at economical cost, the management of water resources is essential. Integrated geological, hydrological (surface and groundwater) and geochemical aspects have been studied for the development and management of water resources in drought-prone Cuddapah district. The main lithological units are crystallines, quartzites, shales and limestones. About 91 000 ha of land in the Cuddapah district is irrigated by canal water. A registered ayacut of about 47 000 ha is irrigated by 1368 minor irrigation tanks. A total of 503 spring channels are identified in the entire district originating from the rivers/streams, which has the capacity of irrigating about 8700 ha. The average seasonal rise in groundwater level is 7.32 m in quartzites, 5.35 m in crystallines, 3.82 m in shales, 2.50 m in limestones and 2.11 m in alluvium. Large quantities of groundwater are available in the mining areas which can be utilised and managed properly by the irrigation department/cultivators for the irrigation practices. Groundwater assessment studies revealed that 584 million m3 of groundwater is available for future irrigation in the district. From the chemical analysis, the quality of groundwater in various rock units is within the permissible limits for irrigation and domestic purposes, but at a few places the specific conductance, chloride and fluoride contents are high. This may be due to untreated effluents, improper drainage system and/or the application of fertilisers. Received: 10 June 1998 · Accepted: 15 November 1998  相似文献   

10.
Development of groundwater modeling for the Azraq Basin, Jordan   总被引：2，自引：1，他引：1  
 The three-dimensional groundwater flow model MODFLOW was applied to simulate water level change in the complex multi-aquifer systems (the Upper and Middle Aquifers) of the Azraq basin. The model was calibrated by matching observed and simulated drawdown for steady and transient states over the period 1970–1992. Drawdown data for the period 1993–1997 were used to test the model's ability to predict the response of the aquifers. The model performed well in representing the water level contours of the Upper and Middle Aquifers for steady state calibration. Agreement between the observed and simulated drawdowns was obtained for transient state calibration. To predict the aquifer system responses for the period of 1997–2025, four different pumping schemes (scenarios) have been investigated. The first scenario (present pumping rate) reveals that there will be approximately a 25 m drop in the water level at the well-field area in 2025. However, the worst scenario (pumping rate at 1.5 times the present rate) reveals an approximate 39 m drop in the water level at the well-field area in 2025. The safe yield for the Upper Aquifer System was found to be about 25 million cubic meters (MCM) yearly. Received: 24 June 1999 · Accepted: 30 November 1999  相似文献   

11.
The study investigates the groundwater evolution and its residence time in the Ejina Basin, northwest China according to isotope and hydrochemical analyses results. The groundwater chemistry is mainly controlled by the dissolution of halite, Glauber’s salt, gypsum, dolomite and calcite, also influenced by other processes such as evaporation, ion exchange, and deposition. Based on tritium content in atmospheric precipitation and by adopting a model with exponential time distribution function, the mean residence time of the unconfined aquifer groundwater with fairly high tritium activities (21–49 TU) is evaluated. The results show that these groundwaters have low residence time (5–120 years) and are renewable. In contrast, the deep confined groundwaters are tritium-free and radiocarbon values range from 18.3 to 26.7 pmc. According to the most commonly used 14C correction models, the radiocarbon groundwater ages were calculated which yield ages of approximately 4,087–9,364 years BP. Isotopic signatures indicate formation of deep confined groundwaters in a colder and wetter climate during the late Pleistocene and Holocene. It is suggested that long-term, rational water usage guide should be set up for the Heihe River Basin as a whole to permit a considerable discharge to the Ejina Basin.  相似文献   

12.
 The aquifer system of the Upper Triassic Keuper Sandstone, an important source of drinking water in northern Bavaria, is affected by elevated arsenic concentrations. Within the study area of 8000 km2, no evidence exists for any artificial source of arsenic. Data from about 500 deep water wells show that in approximately 160 wells arsenic concentrations are 10–150 μg/L. The regional distribution of arsenic in the groundwater shows that elevated arsenic concentrations are probably related to specific lithofacies of the aquifers that contain more sediments of terrestrial origin. Geochemical measurements on samples from four selected well cores show that arsenic has accumulated in the rocks. This indigenous arsenic is the source of arsenic in the groundwater of certain facies of the middle unit of the Keuper Sandstone. Received, June 1998 / Revised, January 1999, May 1999 / Accepted, June 1999  相似文献   

13.
 To accurately measure the pH, Eh, EC and temperature of groundwater retrieved from boreholes, a deep groundwater sampling apparatus was developed which provided sensory measurements both in situ and in a flow-through cell at ground level. Under a pressure of 1×106 Pa the in situ accuracy of the apparatus sensor was within the following limits: pH ±0.2, temperature ±0.1°C, Eh ±10 mV, and EC ±2.4%. The measuring and sampling of deep groundwater from a borehole of more than 1000 m in depth was performed continuously for 30 days. Values of pH were the same for the in situ sensor, the flow-through cell sensor and the laboratory measurements of the sampled water. At the beginning of the sampling period, Eh values of the in situ sensor indicated deep groundwater conditions. The apparatus is particularly useful for Eh measurement. Chemical composition and stable isotope ratios indicated that the groundwater sampled from more than 1000 m depth was a connate water with a chemical composition slightly different from seawater of the present time, and the groundwater retrieved from 800 m depth was a meteoric water. Natural radioactive elements are thought to be the origin of the tritium in the groundwater retrieved from the 1000 m depth. Received: 6 August 1996 / Accepted: 22 October 1996  相似文献   

14.
Tritium is a short-lived radioactive isotope (T 1/2=12.33 yr) produced naturally in the atmosphere by cosmic radiation but also released into the atmosphere and hydrosphere by nuclear activities (nuclear power stations, radioactive waste disposal). Tritium of natural or anthropogenic origin may end up in soils through tritiated rain, and may eventually appear in groundwater. Tritium in groundwater can be re-emitted to the atmosphere through the vadose zone. The tritium concentration in soil varies sharply close to the ground surface and is very sensitive to many interrelated factors like rainfall amount, evapotranspiration rate, rooting depth and water table position, rendering the modeling a rather complex task. Among many existing codes, SOLVEG is a one-dimensional numerical model to simulate multiphase transport through the unsaturated zone. Processes include tritium diffusion in both, gas and liquid phase, advection and dispersion for tritium in liquid phase, radioactive decay and equilibrium partitioning between liquid and gas phase. For its application with bare or vegetated (perennial vegetation or crops) soil surfaces and shallow or deep groundwater levels (contaminated or non-contaminated aquifer) the model has been adapted in order to include ground cover, root growth and root water uptake. The current work describes the approach and results of the modeling of a tracer test with tritiated water (7.3×108 Bq m−3) in a cultivated soil with an underlying 14 m deep unsaturated zone (non-contaminated). According to the simulation results, the soil’s natural attenuation process is governed by evapotranspiration and tritium re-emission. The latter process is due to a tritium concentration gradient between soil air and an atmospheric boundary layer at the soil surface. Re-emission generally occurs during night time, since at day time it is coupled with the evaporation process. Evapotranspiration and re-emission removed considerable quantities of tritium and limited penetration of surface-applied tritiated water in the vadose zone to no more than ∼1–2 m. After a period of 15 months tritium background concentration in soil was attained.  相似文献   

15.
The aim of this study was to determine geochemical properties of groundwater and thermal water in the Misli Basin and to assess thermal water intrusion into shallow groundwater due to over-extraction. According to isotope and hydrochemical analyses results, sampled waters can be divided into three groups: cold, thermal, and mixed waters. Only a few waters reach water–rock chemical equilibrium. Thermal waters in the area are characterized by Na+–Cl−–HCO3−, while the cold waters by CaHCO3 facies. On the basis of isotope results, thermal waters in the Misli basin are meteoric origin. In particular, δ18O and δ2H values of shallow groundwater vary from −10.2 to −12.2‰ and −71.2 to −82‰, while those of thermal waters range from −7.8 to −10.1‰ and from −67 to −74‰, respectively. The tritium values of shallow groundwater having short circulation as young waters coming from wells that range from 30 to 70 m in depth vary from 10 to 14 TU. The average tritium activity of groundwater in depths more than 100 m is 1.59 ± 1.16, which indicates long circulation. The rapid infiltration of the precipitation, the recycling of the evaporated irrigation water, the influence of thermal fluids and the heterogeneity of the aquifer make it difficult to determine groundwater quality changes in the Misli Basin. Obtained results show that further lowering of the groundwater table by over-consumption will cause further intrusion of thermal water which resulted in high mineral content into the fresh groundwater aquifer. Because of this phenomenon, the concentrations of some chemical components which impairs water quality in terms of irrigation purposes in shallow groundwaters, such as Na+, B, and Cl−, are highy probably expected to increase in time.  相似文献   

16.
Mathura oil refinery was commissioned during 1977 and effluent storage ponds were constructed at the same time. These storage ponds receive wastewater from the refinery at a rate of 10000 m3/day. After treatment, waste water is discharged through a 3-km pipeline to a stream leading to the Yamuna river. The groundwater-monitoring as well as water-quality monitoring was carried at 24 observation wells in the refinery site during 1997. The water quality measurements indicated total dissolved chloride and sulphate concentration of native groundwater as 400 mg/l, whereas elevated levels up to 600 mg/l were found at the wells close to polishing ponds. Thus combined transport of chloride and sulphate was simulated in the mass transport model. A three-dimensional flow, pathlines and mass transport model of the aquifer system were constructed to analyze the impact of seepage from polishing ponds contaminating the groundwater regime. The permeability of aquifer varies between 1.5–2.5 m/day. The porosity of formation was assumed as 0.2. The constant head and constant concentration boundaries were assigned to the nodes representing effluent storage ponds. Longitudinal dispersivity of 100 m, horizontal transverse dispersivity of 10 m and vertical transverse dispersivity of 0.01 m were assumed. The mass transport model was calibrated for 20 years by comparing total dissolved chloride and sulphate concentrations from 1997. The model predictions indicate further migration of contaminants on the east of effluent ponds in future. Received: 4 January 1999 · Accepted: 12 July 1999  相似文献   

17.
Groundwater chemistry and tracer-based age data were used to assess contaminant movement and geochemical processes in the middle Claiborne aquifer (MCA) of the Mississippi embayment aquifer system. Water samples were collected from 30 drinking-water wells (mostly domestic and public supply) and analyzed for nutrients, major ions, pesticides, volatile organic compounds (VOCs), and transient age tracers (chlorofluorocarbons, tritium and helium-3, and sulfur hexafluoride). Redox conditions are highly variable throughout the MCA. However, mostly oxic groundwater with low dissolved solids is more vulnerable to nitrate contamination in the outcrop areas east of the Mississippi River in Mississippi and west Tennessee than in mostly anoxic groundwater in downgradient areas in western parts of the study area. Groundwater in the outcrop area was relatively young (apparent age of less than 40 years) with significantly (p < 0.05) higher dissolved oxygen and nitrate–N concentrations and higher detections of pesticides and VOCs compared to water samples from wells in downgradient areas. Oxygen reduction and denitrification rates were low compared to other aquifers in the United States (zero order rate constants for oxygen reduction and denitrification were 4.7 and 5–10 μmol/L/year, respectively). Elevated concentrations of nitrate–N, and detections of pesticides and VOCs in some deep public supply wells (>50 m depth) indicated contaminant movement from shallow parts of the aquifer into deeper oxic zones. Given the persistence of nitrate in young oxic groundwater that was recharged several decades ago, and the lack of a confining unit, the downward movement of young contaminated water may result in higher nitrate concentrations over time in deeper parts of the aquifer containing older oxic water.  相似文献   

18.
 The giant Mercosul aquifer system consists of Triassic-Jurassic eolian-fluvio-lacustrine sandstones confined by Cretaceous basalt flows, and it covers about 1,195,500 km2 (461,583 miles2) in South America. The aquifer system encompasses all of the Paraná Basin and part of the Chaco-Paraná Basin and is one of the world's largest. The eolian Botucatu Sandstone and its equivalents form an important part of this system. Maps of structure, thickness of overlying rocks, and water temperature, and a potentiometric map, all based on 322 wells, define hydrogeologic characteristics and provide the basis for establishing guidelines for the long-term equilibrium use of this important multinational aquifer system. The Mercosul aquifer system is divided into two domains – the larger and better understood Paraná Basin and the smaller and less well understood Chaco-Paraná Basin. Most of the northern part of the Paraná Basin has axially-directed groundwater flow, whereas the southern part of the aquifer discharges mostly to the southwest into the Corrientes Province of Argentina, with negligible discharge into the Atlantic Ocean. The Mercosul aquifer system is conservatively estimated to have been flushed at least 180 times since deposition. Various factors are responsible for this flushing, including appreciable rainfall since the end of the Cretaceous Period, probable uplift of the basins' borders in Late Cretaceous time, simple basin geometry, long-term riverine and groundwater flow to the southwest (ancestral and present Paraná River Systems), and stable cratonic setting. Key hydraulic properties of the Mercosul aquifer system are compared to those of the eolian Jurassic Navajo-Nugget System of the western United States. The results demonstrate the importance of tectonics and climate on the evolution of sub-continental aquifer systems. Received, September 1997 / Revised, December 1998 / Accepted, January 1999  相似文献   

19.
 Salt-water discharges from a fault system in the crystalline basement of the Black Forest into the gravel aquifer of the Kinzig River valley near Ohlsbach, upper Rhine River valley, southwestern Germany. The salt water (TDS, 16 g/kg) ascends from a reservoir at  1 3 km depth. Once discharged into the gravel aquifer, the saline deep water mixes with fresh groundwater and is carried along the groundwater flow path to the middle of the Rhine River valley. There, the natural geogene salt-water plume merges with a man-made chloride-rich infiltration zone along the Rhine River. The plume was mapped using (1) chloride data from groundwater observation wells, and (2) resistivity data from geoelectric sounding. Background chloride is about 7 mg/kg. In the central region of the plume, chloride concentration exceeds 200 mg/kg. A continuous area of Cl  1 50 mg/kg is distinguished from the discharge fault to the Rhine River over a distance of 12 km. Resistivities range from  1 50 Ω in uncontaminated regions to <7 Ω in the 700 m-long central region of the plume. A low resistivity plume (7–10 Ω) stretches for  1 7 km into the Rhine River valley. The two plume maps are in good agreement. Received, April 1998 / Revised, November 1998, January 1999 / Accepted, January 1999  相似文献   

20.
 The Dawu well field, one of the largest in China, supplies most of the water for the Zibo City urban area in Shandong Province. The field yields 522,400–535,400 m3/d from an aquifer in fractured karstic Middle Ordovician carbonate rocks. Much of the recharge to the aquifer is leakage of surface water from Zihe Stream, the major drainage in the area. Installation of the Taihe Reservoir in 1972 severely reduced the downstream flow in Zihe Stream, resulting in a marked reduction in the water table in the Dawu field. Since 1994, following the installation of a recharge station on Zihe Stream upstream from the well field that injects water from the Taihe Reservoir into the stream, the groundwater resources of the field have recovered. An average of 61.2×103 m3/d of groundwater, mostly from the Ordovician aquifer, is pumped from the Heiwang iron mine, an open pit in the bed of Zihe Stream below the Taihe Reservoir. A stepwise regression equation, used to evaluate the role of discharge from the reservoir into the stream, confirms that reservoir water is one of the major sources of groundwater in the mine. Received, May 1998 / Revised, May 1999 / Accepted, June 1999  相似文献   

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