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1.
《中国地球化学学报》2006,25(B08):60-60
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2.
Fluoride poisoning is the most widespread and serious endemic disease in the inland river basins of northern China, where igneous rocks containing F-rich minerals of the Yanshan stage (Jurassic-Cretaceous) are extensively exposed in mountainous area. In I…  相似文献   

3.
The Bet She’an and Harod Valleys are regional recipients and mixing zones for groundwater draining to these valleys from a multiple aquifer system. This aquifer system includes two different carbonate aquifers, several groundwater-bearing basalt flows and deep-seated pressurized brine, the upflow of which causes salinization of fresh groundwater bodies. These aquifers drain through two groups of springs. Due to lack of information on the subsurface structure of the valley the flow-paths of groundwater feeding the springs, the initial distribution of salinities along the valley and particularly, the inflow-paths of the brines, have never been understood but were assumed to be fault-controlled. The interpretation of seismic profiles and analysis of gravity anomalies revealed the subsurface structure of the valley and namely the occurrence of a dense network of faults which branch out from those delineating the Jordan-Dead Sea Rift. The faults formed a series of uplifted and down-warped horst-and-graben structures. By joint analysis of structural, hydrological and geochemical evidence, it occurs that groundwater flow-paths leading to the springs emerging in the middle of the Bet She’an Valley are determined by structural elements such as major faults and fault-controlled structures. The penetration of the pressurized Ca-chloride Rift brines and their inflow into fresh groundwater bodies occurs prevalently along the faults outlining the western margins of the Dead Sea Rift Valley and at their intersection with outbranching NW–SE-striking faults.  相似文献   

4.
Water management in semiarid and arid catchments such as the Poopó Lake Basin requires improved understanding of the complex behavior of the various contaminants, which affect the drinking water quality and considered as crucial for sustainable development of the region. Mechanisms of arsenic (As) release in the surface and groundwater were studied. Hydrochemical data for surface water (4 samples) and groundwater (28 samples) were collected in a small watershed in the Poopó catchment at the highland of the Bolivian Andes (Altiplano). All of them show high electrical conductivity values and moderately oxidizing conditions. The surface water contains high concentration of sulfate and the trace elements As, Zn and Pb in the zone affected by acid mine drainage. There is a large variability of the concentration of As and of the trace elements in the groundwater in the five different regions within the Poopó catchment. The metal concentrations sensitive to changes of redox state and results of speciation modeling suggest that As (V) is a predominant aqueous species, which conforms to the prevailing oxidizing conditions in the shallow groundwater environment. Two generalized trends for As distribution were identified in groundwater: (a) high concentrations are found in the arid zone (100–250 μg/L) in the southern (region III) and in the northwestern (region V) regions, and (b) low concentrations (<50 μg/L) are found in the remaining part of the basin (region I, II and IV). However, the spatial distribution within these regions needs to be investigated further. A conclusion from the present study is that there are multiple sources of As as well as other trace elements (such as Cd, Mn and Zn) in the Poopó Lake Basin. Among the sources and the processes which led to the mobility of As and other trace metals in the region are: (a) weathering of sulfide minerals, (b) oxidation of pyrite and/or arsenopyrite in mineralized areas and (c) desorption from hydrous ferric oxide (HFO) surfaces. In non-mining areas, volcanic ash is suggested to be a significant source of As.  相似文献   

5.
Ground water levels and quality in Chhatna Block of West Bengal were studied based on different indices for irrigation and drinking purposes. A detailed hydrogeological investigation was carried out to have an overall idea of the aquifer system of the area. The ground water occurs under shallow to moderately deep water table condition. The groundwater is stored mostly in the weathered residuum and fractured — hard rock. Sodium absorption ratio (SAR), soluble sodium percentage (SSP), residual sodium bi-carbonate (RSBC), electrical conductance (EC), magnesium adsorption ratio (MAR) Kelly’s ratio (KR), total hardness (TH), permeability index (PI) were calculated as derived parameters, to investigate the ionic toxicity. From the results of chemical analysis, it was revealed that the values of Sodium Adsorption Ratio indicate that, ground water of the area falls under the category of low sodium hazard. So, there was neither salinity nor toxicity problem of irrigation water, and hence the ground water can safely be used for long-term irrigation. Plotting of analytical results of the groundwater collected from different areas in Piper’s trilinear diagram (1944) indicate that, the waters of the study area fall under fresh and sulphate rich region of the rhombus.  相似文献   

6.
In this paper, we present an original methodology for recovering boundary conditions and hydraulic parameters in an aquifer domain. Boundary data are identified from the knowledge of over-specified boundary data on another part of the boundary. Then parameters, here wells’ positions and fluxes, are recovered by the use of the reciprocity principle (Andrieux and Ben Abda, Mech Res Commun 20:415–420, 1993; Andrieux and Ben Abda, Inverse Probl 12:553–564, 1996). The boundary recovering method is based on the minimization of an energy-like error functional (Andrieux et al., Inverse Probl 22:115–133; Baranger and Andrieux, 2010).  相似文献   

7.
The US High Plains aquifer, one of the largest freshwater aquifer systems in the world, continues to decline, threatening the long-term viability of the region’s irrigation-based economy. The eight High Plains States take different approaches to the development and management of the aquifer based on each state’s body of water laws that abide by different legal doctrines, on which Federal laws are superposed, thus creating difficulties in integrated regional water-management efforts. Although accumulating hydrologic stresses and competing demands on groundwater resources are making groundwater management increasingly complex, they are also leading to innovative management approaches, which are highlighted in this paper as good examples for emulation in managing groundwater resources. It is concluded that the fragmented and piecemeal institutional arrangements for managing the supplies and quality of water are inadequate to meet the water challenges of the future. A number of recommendations for enhancing the sustainability of the aquifer are presented, including the formation of an interstate groundwater commission for the High Plains aquifer along the lines of the Delaware and Susquehanna River Basins Commissions in the US. Finally, some lessons on groundwater management that other countries can learn from the US experience are outlined.  相似文献   

8.
The hydrodynamic processes and impacts exerted by river–groundwater transformation need to be studied at regional and catchment scale, especially with respect to diverse geology and lithology. This work adopted an integrated method to study four typical modes (characterized primarily by lithology, flow subsystems, and gaining/losing river status) and the associated hydrodynamic processes and ecological impacts in the southern part of Junggar Basin, China. River–groundwater transformation occurs one to four times along the basin route. For mode classification, such transformation occurs: once or twice, controlled by lithological factors (mode 1); twice, impacted by geomorphic features and lithological structures (mode 2); and three or four times, controlled by both geological and lithological structures (modes 3 and 4). Results also suggest: (1) there exist local and regional groundwater flow subsystems at ~400 m depth, which form a multistage nested groundwater flow system. The groundwater flow velocities are 0.1–1.0 and?<0.1 m/day for each of two subsystems; (2) the primary groundwater hydro-chemical type takes on apparent horizontal and vertical zoning characteristics, and the TDS of the groundwater evidently increases along the direction of groundwater flow, driven by hydrodynamic processes; (3) the streams, wetland and terminal lakes are the end-points of the local and regional groundwater flow systems. This work indicates that not only are groundwater and river water derived from the same source, but also hydrodynamic and hydro-chemical processes and ecological effects, as a whole in arid areas, are controlled by stream–groundwater transformation.  相似文献   

9.
In southern Rocky Mountains, catchments characterized by acidic, metalliferous waters that are relatively unaffected by human activity usually occur within areas that have active or historical mining activity. The US Geological Survey has utilized these mineralized but unmined catchments to constrain geochemical processes that control the surface- and ground-water chemistry associated with near surface acid weathering as well as to estimate premining conditions. Study areas include the upper Animas River watershed, Lake City, Mt. Emmons, and Montezuma in Colorado and Questa in New Mexico. Although host-rock lithologies range from Precambrian gneisses to Cretaceous sedimentary units to Tertiary volcanic complexes, mineralization is Tertiary in age and associated with intermediate to felsic composition, porphyritic plutons. Pyrite is ubiquitous. Variability of metal concentrations in water is caused by two main factors： mineralogy and hydrology. Parameters that potentially affect water chemistry include： host-rock lithology, intensity of hydrothermal alteration, sulfide mineralogy and chemistry, gangue mineralogy, length of flow path, precipitation, evaporation, and redox conditions. Springs and headwater streams have pH values as low as 2.5, sulfate up to 3700 mg/L and high dissolved metal concentrations （for example： Al up to 170 mg/L; Fe up to 250 mg/L; Cu up to 3.5 mg/L and Zn up to 14 mg/L）. With the exception of evaporative waters, the lowest pH values and highest Fe and Al concentrations occur in water draining the most intense hydrothermally altered areas consisting of the mineral assemblage quartz-sericite-pyrite. Stream beds tend to be coated with iron floc, and some reaches are underlain by ferricrete. When iron-rich ground water interacts with oxygenated waters in the stream or hyporheic zone, ferrous iron is oxidized to ferric iron, which is less soluble, leading to the precipitation of iron oxyhydroxides.  相似文献   

10.
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11.
The leaching processes along the flow path and over abstraction of the alluvial aquifer, the principal aquifer in delta Tokar, by the agricultural and domestic sectors and natural factors, have led to its salinization which may be due to interaction between geological formations and adjacent brackish and saline water bodies as well as seawater transgression. The main objectives of this study are to assess the hydrochemical characteristics of the groundwater and to delineate the locations and the sources of aquifer salinization. Water samples in the project area were chemically analyzed for major cations and anions at the laboratory by the standard analytical procedures. Chemical data and water level measurements were manipulated using GIS techniques for hydro chemical and flow direction maps and piper diagram for chemical facies and SPSS software for statistical analyses such as basic statistics (mean and standard deviation) and Spearman’s correlation matrix. The general flow direction of the groundwater is from Southwest towards East and Northeast. The hydraulic gradient is relatively steeper at the apex of the delta (0.06) and amounts to 0.005 at the distal part of the delta. The average transmissivity value of the water bearing formations was found to be about 4.5?×?103 m2/s, whereas, the storage coefficient was about 0.28. A hydrochemical study identified the locations and the sources of aquifer salinization and delineated their areas of influence. The investigation indicates that the aquifer water quality is significantly modified as groundwater flows from the southwestern parts of the study area, where the aquifer receives its water by lateral underflow from Khor Baraka flood plain, to the central and northeastern parts, with few exceptions of scattered anomalous concentration pockets in the deltaic plain. Significant correlation between TDS and/or EC with the major components of Na+, Cl?, and SO 4 ?2 ions is an indication of seawater influence on the groundwater salinity. Moreover, Cl?, SO 4 2? , and Na+ are predominant ions followed by Ca2+ and HCO 3 ? . Hence, four types of groundwater can be chemically distinguished: Na–Ca–SO4–Cl– facies, Na–Cl–SO4–HCO3– facies, Na–Ca–Mg–SO4–Cl–HCO3 facies, and Na–Ca–Mg–Cl–SO4 facies. The processes that govern changes in groundwater composition as revealed by chemical and statistical analyses are mainly associated with over-abstraction, biodegradation, marine intrusions, and carbonate saturation.  相似文献   

12.
The present study is the first attempt to determine the suitability of groundwater for drinking and irrigation in the Baga–Calangute stretch of Goa. The suitability of groundwater for potable use was assessed by comparing observed values against standards prescribed by the Bureau of Indian Standards, and the quality was classified based on the Weighted Arithmetic Water Quality Index. Most of the groundwater samples (90%) were found to be suitable for drinking except for hardness, chlorides, and nitrates. The percent sodium (%Na), residual sodium carbonate, soluble sodium percentage, sodium adsorption ratio, Kelly’s ratio, and Permeability Index were found to be within the prescribed limits for irrigation purposes. The major mechanism controlling groundwater chemistry, i.e., rock–water interaction, was also studied, and it was found that silicate weathering plays a major role in the dissolution of minerals. Based on the hydrochemical characterization, the water was observed to be of the Ca–Na–SO4 composition type except for one sample which was of the Na–Cl composition type. Classification of the meteoric genesis suggested that the groundwater in surficial aquifers in the region had a deep meteoric percolation, and its chemistry is regulated by rock–water interaction.  相似文献   

13.
The characteristics of arsenic-contaminated groundwater were investigated and the potential risks from groundwater were evaluated in Vietnam. Arsenic contamination in groundwater was found in Ha Nam Province in the northern part of Vietnam. Since groundwater has been used as one of the main drinking water sources in this region, groundwater （n=10） and hair （n=15） samples were collected in the Vinh Tru district, Ha Nam Province, during February of 2006. At the site, the concentrations of anions and silica were analyzed and As（Ⅲ） and As（Ⅴ） species in groundwater were separated with disposable arsenic speciation cartridge. The concentrations of arsenic in groundwater ranged from 13 to 582 μg/L （mean=366 μg/L）. According to the results of arsenic speciation, approximately 90% of arsenic in groundwater existed as As（Ⅲ） species. Average concentrations of iron and manganese were 18 and 0.7 mg/L, respectively. All samples exceeded the Vietnamese drinking water standard of 10μg/L for arsenic and 0.5 mg/L for iron. Also 70% of the groundwater samples were above the Vietnamese drinking water standard of 0.5 mg/L for manganese. However, a real intake of arsenic to human is less than analyzed arsenic concentration because sand filtration units are used to remove iron and arsenic in groundwater in this region. After treatment, arsenic concentrations decreased from 〈1 to 82 μg/L （mean=33 μg/L）. The concentrations of arsenic in hair samples and treated groundwater were compared. Especially, arsenic concentrations in female hair samples and treated groundwater had significantly positive correlation with the Spearman correlation of 0.88 and the P-value of 0.001. Based on the arsenic concentrations in treated groundwater, the assessment of human health risks was conducted.  相似文献   

14.

The Mio-Pliocene aquifer of the coastal sedimentary basin of Benin is the most exploited aquifer for water supply to the urbanised region in the southern part of the country. The population explosion is putting increasing pressure on quantitative and qualitative aspects of the groundwater resources. Preventing groundwater contamination caused by surface waters requires a thorough understanding of surface-water/groundwater interactions, especially the interactions between the Mio-Pliocene aquifer and surface waters. This study aimed to investigate the interactions between groundwater and surface waters along the major rivers (Sô River and Ouémé Stream) and brooks in the Ouémé Delta. Field campaigns identified 75 springs located in the valleys which feed the rivers, and thus maintain their base flow. The piezometric results indicated, through flow direction assessment, that the Mio-Pliocene aquifer feeds Ouémé Stream and Sô River. Chemical analyses of groundwater and surface waters show similar chemical facies, and changes in the chemical composition in groundwater are also observed in the surface waters. Moreover, the isotopic signatures of surface waters are similar to those of the groundwater and springs, which led to the identification of potential groundwater discharge areas. As a result of groundwater discharge into surface waters, the fraction of groundwater in the surface water is more than 66% in the brooks, regardless of the season. In the Ouémé Stream and Sô River, the fraction of groundwater is 0–21% between June and September, while from October to March it is 47–100%.

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15.
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16.
Small quantities of groundwater interact with hydrothermal surface water to drive in-stream geochemical processes in a silica-armored hot-spring outflow channel in Yellowstone National Park, USA. The objective of this study was to characterize the hydrology and geochemistry of this unique system in order to (1) learn more about the Yellowstone Plateau’s subsurface water mixing between meteoric and hydrothermal waters and (2) learn more about the chemical and physical processes that lead to accumulation of streambed cements, i.e., streambed armor. A combination of hydrological, geochemical, mineralogical, microscopic, and petrographic techniques were used to identify groundwater and surface-water exchange. Interaction could be identified in winter because of differences in surface water and groundwater composition but interaction at other times of the year cannot be ruled out. Dissolved constituents originating from groundwater (e.g., Fe(II) and Mg) were traced downstream until oxidation and/or subsequent precipitation with silica removed them, particularly where high affinity substrates like cyanobacterial surfaces were present. Because the stream lies in a relatively flat drainage basin and is fed mainly by a seasonally relatively stable hot spring, this system allowed study of the chemical processes along a stream without the obscuring effects of sedimentation.  相似文献   

17.
We collected groundwaters in and around a large (313 Mt at 1.08% Cu and 0.3% cutoff) undisturbed porphyry copper deposit (Spence) in the hyperarid Atacama Desert of northern Chile, which is buried beneath 30–180 m of Miocene piedmont gravels. Groundwaters within and down-flow of the Spence deposit have elevated Se (up to 800 μg/l), Re (up to 31 μg/l), Mo (up to 475 μg/l) and As (up to 278 μg/l) concentrations compared to up-flow waters (interpreted to represent regional groundwater flow). In contrast, Cu is only elevated (up to 2036 μg/l) in groundwaters recovered from within the deposit; Cu concentrations are low down gradient of the deposit. The differential behavior of the metals/metalloids occurs because the former group dissolves as anions, enhancing their mobility, whereas the base metals dissolve as cations and are lost from solution most likely through adsorption to clay surface exchange sites and through formation of secondary copper chlorides, carbonates, and oxides. Most groundwaters within and down-flow of the deposit have Eh–pH values around the FeII/FeIII phase boundary, limiting the impact of Fe-oxyhydroxides on oxyanions mobility. Se, Re, Mo, and As are all mobile (with filtered/unfiltered samples ～ 1) to the limit of sampling 2 km down gradient from the deposit. The increase in ore-related metals, metalloids, and sulfate and decrease in sulfate–S isotope ratios (from values similar to regional salars, + 4 to + 8‰ δ34SCDT to lower values closer to hypogene sulfides, + 1 to + 4‰ δ34SCDT) is consistent with active water–rock reactions between saline groundwaters and the Spence deposit. It is likely that hypogene and/or supergene sulfides are being oxidized under the present groundwater conditions and mineral saturation calculations suggest that secondary copper minerals (antlerite, atacamite, malachite) may also be actively forming, suggesting that supergene and exotic copper mineralization is possible even under the present hyperarid climate of the Atacama Desert.  相似文献   

18.
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19.
Changes in the climatic system introduce uncertainties in the supply and management of water resources. The Intergovernmental Panel on Climate Change(IPCC) predicts an increase of 2 to 4 °C over the next 100 years. Temperature increases will impact the hydrologic cycle by directly increasing the evaporation of surface water sources. Consequently, changes in precipitation will indirectly impact the flux and storage of water in surface and subsurface reservoirs(i.e., lakes, soil moisture, groundwater, etc.). In addition, increases in temperature contribute to increases in the sea level, which may lead to sea water intrusions, water quality deterioration, potable water shortages, etc. Climate change has direct impacts on the surface water and the control of storage in rivers, lakes and reservoirs, which indirectly controls the groundwater recharge process. The main and direct impact of climate change on groundwater is changes in the volume and distribution of groundwater recharge. The impact of climate change on groundwater resources requires reliable forecasting of changes in the major climatic variables and accurate estimations of groundwater recharge. A number of Global Climate Models(GCMs) are available for understanding climate and projecting climate change.These GCMs can be downscaled to a basin scale, and when they are coupled with relevant hydrological models, the output of these coupled models can be used to quantify the groundwater recharge, which will facilitate the adoption of appropriate adaptation strategies under the impact of climate change.  相似文献   

20.
Hydrochemical and isotopic study of Miocene and Mio-Plio-Quaternary (M-P-Q) aquifers in Wadi El Hechim?CGaraa Hamra basin, Central Tunisia was undertaken in order to investigate recharge mode and processes leading to mineralization of groundwater as well as interaction between both systems. The results revealed striking differences between the two aquifer systems. While the Miocene aquifer contains recently recharged waters with generally low mineralization (around 0.5?g?L?1), stemming mainly from dissolution of carbonate minerals, the M-P-Q aquifer reveals TDS values reaching 3?g?L?1, controlled mainly by dissolution of evaporitic minerals. Isotopic data indicate that the Miocene aquifer contains water recharged in past several decades (bomb tritium and bomb radiocarbon detected). The M-P-Q system appears to be much slower, with time scales of groundwater flow possibly reaching some thousands of years. Sharp discontinuity of hydrochemical and isotope characteristic of groundwater observed across the major tectonic fault separating the Miocene and M-P-Q aquifers supports the idea of very limited (if any) hydraulic interconnection between both studied systems. This in turn calls for revision of existing conceptual models of groundwater flow in the region postulating significant groundwater fluxes crossing the fault in the direction of M-P-Q aquifer and adjacent aquifers in the Wadi al Fakka plain.  相似文献   

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