首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
The study area covers an about 100 km2 of the middle Ganga plain in Uttar Pradesh, experiencing intensive groundwater extraction. In order to recognize the arsenic contamination zones of the Varanasi environs, sixty eight groundwater samples have been collected and analyzed for major ions, iron and arsenic. Twenty one sediment samples in the four boreholes were also collected to deduce the source of arsenic in the groundwater. The preliminary survey reports for the first time indicates that part of rural and urban population of Varanasi environs are drinking and using for irrigation arsenic contaminated water mostly from hand tube wells (<70 m). The study area is a part of middle Ganga plain which comprises of Quaternary alluvium consists of an alternating succession of clay, clayey silt and sand deposits. The high arsenic content in groundwater samples of the study area indicates that 14% of the samples are exceeding the 10 μg/l and 5% of the samples are exceeding 50 μg/l. The high arsenic concentration is found in the villages such as Bahadurpur, Madhiya, Bhojpur, Ratanpur, Semra, Jalilpur, Kateswar, Bhakhara and Kodupur (eastern side of Ganga River in Varanasi), situated within the newer alluvium deposited during middle Holocene to Recent. The older alluvial aquifers situated in the western side of the Ganga River are arsenic safe (maximum As concentration of 9 μg/l) though the borehole sediments shows high arsenic (mean 5.2 mg/kg) and iron content (529 mg/kg) in shallow and medium depths. This may be due to lack of reducing conditions (i.e organic content) for releasing arsenic into the groundwater. Rainfall infiltration, organic matter from recently accumulated biomass from flood prone belt in the newer alluvium plays a critical role in releasing arsenic and iron present in sediments. The main mechanism for the release of As into groundwater in the Holocene sandy aquifer sediments of Varanasi environs may be due to the reductive dissolution of Fe oxyhydroxide present as coatings on sand grains as well as altered mica content. The high societal problems of this study will help to mitigate the severity of arsenic contamination by providing alternate drinking water resources to the people in middle Ganga plain and to arrange permanent arsenic safe drinking water source by the authorities.  相似文献   

2.
The concentration of arsenic measured in groundwater from three aquifers in the study area located in the Eastern Tucuman province, Argentina, mostly depends on the lithology, but the spatial and temporal variations of concentrations seem to be also controlled by pH changes, climatic factors, and human perturbations. The highest concentrations of As (more than 1,000 μg L−1) were found in the shallow aquifer, made of As-rich loess, while the lowest concentrations were measured in the deep confined aquifer, consisting of alternating layers of alluvial sands/gravels and clays. Intermediate values were measured in the semiconfined aquifer made of the fluvial sediments deposited in the Salí River valley, that alternate in the upper part of the sedimentary sequence with layers of loess. Because most of As in the loess is considered to be adsorbed onto Fe-oxyhydroxide coatings, the increase of pH in the flow direction (west-east) leads to increasing arsenic concentrations towards the eastern border of the study area. The decomposition of organic wastes poured into the Salí River or associated with local and diffuse sources of contamination in the eastern part of the study area depletes dissolved oxygen, which leads to the reductive dissolution of Fe and Mn oxyhydroxides, and to the subsequent release of the adsorbed and co-precipitated As. This process mainly affects shallow groundwater and the upper part of the semiconfined aquifer. Geochemical and hydrological data also suggest that rising water table levels at the end of the wet season may also lead to reductive dissolution of As-rich Fe oxyhydroxides in the shallow aquifer.  相似文献   

3.
Chemical analyses of 21 water samples from the Firehole and Gibbon Rivers, which combine to form the Madison River, gave arsenic and fluoride values above the Environmental Protection Agency Interim Primary Drinking Water maximum contaminant levels (0.05 mg/l arsenic and 2.0 mg/l fluoride). On 18 October, 1975, during a period of moderate flow (16,600 l/s), the Madison River at West Yellowstone contained 0.23 mg/l arsenic and 6.2 mg/l fluoride. Below Hebgen Lake the Madison River during periods of high flow (56,000 liter/s at West Yellowstone and 708,000 liter/s below Hebgen Lake) would contain 0.05 mg/l arsenic at both stations and 1.5 and 4.0 mg/l fluoride at West Yellowstone and below Hebgen Lake, respectively. The strong correlations of arsenic and fluoride with other chemical constituents of the river water at the sampling sites demonstrate the conservative nature of each element after it reaches the Madison River system. Calculations indicate that water from three sampling sites is above saturation with respect to fluorite.  相似文献   

4.
Manipur State, with a population of 2.29 million, is one of the seven North-Eastern Hill states in India, and is severely affected by groundwater arsenic contamination. Manipur has nine districts out of which four are in Manipur Valley where 59% of the people live on 10% of the land. These four districts are all arsenic contaminated. We analysed water samples from 628 tubewells for arsenic out of an expected total 2,014 tubewells in the Manipur Valley. Analyzed samples, 63.3%, contained >10 μg/l of arsenic, 23.2% between 10 and 50 μg/l, and 40% >50 μg/l. The percentages of contaminated wells above 10 and 50 μg/l are higher than in other arsenic affected states and countries of the Ganga–Meghna–Brahmaputra (GMB) Plain. Unlike on the GMB plains, in Manipur there is no systematic relation between arsenic concentration and the depth of tubewells. The source of arsenic in GMB Plain is sediments derived from the Himalaya and surrounding mountains. North-Eastern Hill states were formed at late phase of Himalaya orogeny, and so it will be found in the future that groundwater arsenic contamination in the valleys of other North-Eastern Hill states. Arsenic contaminated aquifers in Manipur Valley are mainly located within the Newer Alluvium. In Manipur, the high rainfall and abundant surface water resources can be exploited to avoid repeating the mass arsenic poisoning that has occurred on the GMB plains.  相似文献   

5.
The Zlata Idka village is a typical mountainous settlement. As a consequence of more than 500 years of mining activity, its environment has been extensively affected by pollution from potentially toxic elements. This paper presents the results of an environmental-geochemical and health research in the Zlata Idka village, Slovakia. Geochemical analysis indicates that arsenic (As) and antimony (Sb) are enriched in soils, groundwater, surface water and stream sediments. The average As and Sb contents are 892 mg/kg and 818 mg/kg in soils, 195 mg/kg and 249 mg/kg in stream sediments, 0.028 mg/l and 0.021 mg/l in groundwater and 0.024 mg/l and 0.034 mg/l in surface water. Arsenic and Sb concentrations exceed upper permissible limits in locally grown vegetables. Within the epidemiological research the As and Sb contents in human tissues and fluids have been observed (blood, urine, nails and hair) in approximately one third of the village’s population (120 respondents). The average As and Sb concentrations were 16.3 μg/l and 3.8 μg/l in blood, 15.8 μg/l and 18.8 μg/l in urine, 3,179 μg/kg and 1,140 μg/kg in nails and 379 μg/kg and 357 μg/kg in hair. These concentrations are comparatively much higher than the average population. Health risk calculations for the ingestion of soil, water, and vegetables indicates a very high carcinogenic risk (>1/1,000) for as content in soil and water. The hazard quotient [HQ=average daily dose (ADD)/reference dose (RfD)] calculation method indicates a HQ>1 for groundwater As and Sb concentrations.  相似文献   

6.
 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   

7.
The study region covers 1,650 km2 of the Mid-Ganga Basin in Bihar, experiencing intensive groundwater draft. The area forms a part of the Gangetic alluvial plain where high incidence of arsenic groundwater contamination (>50 μg/l) has recently been detected. Seventy-seven groundwater samples have been collected and analysed for major ions, iron and arsenic. Arsenic contamination (max 620 μg/l) is confined in hand pump zones (15–35 m) within the newer alluvium deposited during Middle Holocene to Recent age. The older alluvial aquifers are arsenic-safe and recorded maximum concentration as 9 μg/l. Out of 12 hydrochemical facies identified, four have been found arsenic-affected: Ca–HCO3, Mg–HCO3, Ca–Mg–HCO3 and Mg–Ca–HCO3. The geochemical evolution of groundwater, as investigated by graphical interpretation and statistical techniques (correlation, principal component analysis) revealed that dissolution of detrital calcite, dolomite and infiltration of rainwater are the major processes shaping the groundwater chemistry in the newer alluvium. Arsenic and iron showed strong positive correlation. Rainfall infiltration, carrying organic matter from recently accumulated biomass from this flood-prone belt, plays a critical role in releasing arsenic and iron present in the sediments. Geochemical evolution of groundwater in older alluvium follows a different path, where cation-exchange has been identified as a significant process.  相似文献   

8.
This thesis focuses Arsenic(As) distribution and occurrence in groundwater of Yangtze River Delta economic region, East China. 2019 groundwater samples were collected to analyze 26 chemical compositions, including As. The Principal Component Analysis(PCA) was used to find out As source in groundwater. The results show that average As concentration in groundwater of this study is 9.33 μg/l, and maximum As concentration is up to 510 μg/l. The variation coefficient is 314.34%. High arsenic phreatic water(10 μg/l) distributes along the Yangtze River and its estuary. Weak hydrodynamic conditions, wide p H value variation range and deteriorating environment are dominating factors, especially in Yangtze River Delta. The PCA suggests that arsenic in phreatic water is mainly of natural origin. Part of arsenic may directly originate from sediment organics and be related to organics decomposition.  相似文献   

9.
Evaluation of major ion chemistry and solute acquisition process controlling water chemical composition were studied by collecting a total of fifty-one groundwater samples in shallow (<25 m) and deep aquifer (>25 m) in the Varanasi area. Hydrochemical facies, Mg-HCO3 dominated in the largest part of shallow groundwater followed by Na-HCO3 and Ca-HCO3 whereas Ca-HCO3 is dominated in deep groundwater followed by Mg-HCO3 and Na-HCO3. High As concentration (>50 μg/l) is found in some of the villages situated in northeastern parts (i.e. adjacent to the concave part of the meandering Ganga river) of the Varanasi area. Arsenic contamination is confined mostly in tube wells (hand pump) within the Holocene newer alluvium deposits, whereas older alluvial aquifers are having arsenic free groundwater. Geochemical modeling using WATEQ4F enabled prediction of saturation state of minerals and indicated dissolution and precipitation reactions occurring in groundwater. Majority of shallow and deep groundwater samples of the study area are oversaturated with carbonate bearing minerals and under-saturated with respect to sulfur and amorphous silica bearing minerals. Sluggish hydraulic conductivity in shallow aquifer results in higher mineralization of groundwater than in deep aquifer. But the major processes in deep aquifer are leakage of shallow aquifer followed by dominant ion-exchange and weathering of silicate minerals.  相似文献   

10.
High As contents in groundwater were found in Rayen area and chosen for a detailed hydrogeochemical study. A total of 121 groundwater samples were collected from existing tube wells in the study areas in January 2012 and analyzed. Hydrogeochemical data of samples suggested that the groundwater is mostly Na–Cl type; also nearly 25.62 % of samples have arsenic concentrations above WHO permissible value (10 μg/l) for drinking waters with maximum concentration of aqueous arsenic up to 25,000 μg/l. The reducing conditions prevailing in the area and high arsenic concentration correlated with high bicarbonate and pH. Results show that arsenic is released into groundwater by two major phenomena: (1) through reduction of arsenic-bearing iron oxides/oxyhydroxides and Fe may be precipitated as iron sulfide when anoxic conditions prevail in the aquifer sediments and (2) transferring of As into the water system during water–acidic volcanic rock interactions.  相似文献   

11.
The Guadalupe Valley aquifer is the only water source for one of the most important wine industries in Mexico, and also the main public water supply for the nearby city of Ensenada. This groundwater is monitored for major ion, N-NO3, P-PO4, Fe, As, Se, Mo, Cd, Cu, Pb, Zn and Sb concentrations, as well as TDS, pH, dissolved oxygen and temperature. High concentrations of N-NO3 (26 mg l−1), Se (70 μg l−1), Mo (18 μg l−1) and Cu (4.3 μg l−1) suggest that groundwater is being polluted by the use of fertilizers only in the western section of the aquifer, known as El Porvenir graben. Unlike the sites located near the main recharge area to the East of the aquifer, the water in El Porvenir graben has low tritium concentrations (<1.9 TU), indicating a pre-modern age, and thus longer water residence time. No significant variations in water quality (generally <10%) were detected throughout 2001–2002 in the aquifer, suggesting that reduced rainfall and recharge during this dry period did not significantly affect water quality. However, the wells nearest to the main recharge area in the Eastern aquifer show a slight but constant increase in TDS with time, probably as a result of the high (∼200 L S−1) uninterrupted extraction of water at this specific recharge site. Relatively high As concentrations for the aquifer (10.5 μg l−1) are only found near the northern limit of the basin associated with a geological fault.  相似文献   

12.
Groundwater arsenic distribution in South-western Uruguay   总被引：1，自引：0，他引：1  
This is the first specific information regarding arsenic distribution of groundwater in SW Uruguay. Twenty-eight wells were sampled on the aquifers of Mercedes, Raigón and Chuy in five localities. The pH, specific conductivity and temperature were determined in the field. The hydrochemical characterization (major and trace elements) was carried out by both inductively coupled plasma-optical emission spectrometry and inductively coupled plasma-mass spectrometry. The occurring arsenic concentrations exceed the recommended threshold for drinking water of the World Health Organization (10 μg/l of As) in 22 samples, with more than 50 μg/l of As in two cases. The median, minimum and maximum concentrations were 0.1, 16.9 and 58.0 μg/l of As, respectively. The studied aquifers present a horizontal and a vertical variation of the concentrations as a whole as well as individually. The highest values were observed in the Mercedes Aquifer in the areas near the Uruguay River.  相似文献   

13.
The chemical and microbiological characteristics of groundwater from two provinces of central Spain were studied. In some zones of this area, the concentrations of As in groundwater exceed the guideline concentrations, set internationally between 10 g/l and 50 g/l, reaching levels over 100 g/l. A narrow correlation between the contents of arsenic and HCO3– was observed. These data suggest a possible mechanism of the As mobilization from aquifer sediments to groundwater: the bicarbonate ions could displace HAsO42– adsorbed on aquifer oxyhydroxides. Sediments containing relatively high contents of adsorbed arsenic are deposited in surface water environments with low carbonate concentrations. Subsequently, the sediments become exposed to groundwater with highly dissolved carbonate content, and arsenic can be mobilized by displacement from mineral surfaces. In addition, the presence of Pseudomonas genera bacteria, which secrete siderophores (Fe chelating agents) could mobilize As adsorbed on Fe oxides through their dissolution. These combined microbiological and chemical processes might have increased the natural mobility of As.  相似文献   

14.
Arsenic in groundwaters of the alluvial aquifer of Bardsir plain, SE Iran   总被引：1，自引：1，他引：0  
Bardsir plain is located in the central part of Kerman Province of Iran. The relative prevalence of arsenic-related cancers, the high concentration of arsenic in nearby plains, as well as the recharge of this aquifer through the mountains composed of high-sulfide volcanic rocks have been motivations of the authors to study the concentration of this element in Bardsir plain. Arsenic concentration was measured in 63 groundwater samples using inductively coupled plasma mass spectrometry method. The results were evaluated through iso-concentration maps, correlation diagrams, and multivariate statistical methods. Accordingly, the concentration of arsenic ranges from 1.3 to 464.5 μg/l with an average value of 134.2 μg/l. So, the groundwaters are enriched with arsenic to much higher levels than permitted for than drinking water acceptable level (10 μg/l). The high arsenic levels in groundwaters of Bardsir plain are ascribed to joint influence of decomposition of sulfides present in mountainous volcanic rocks and the mixing with hydrothermal waters in some locations. Supposedly, the prevalence of higher than 8 pH values has enhanced the release of arsenic from Fe-hydroxides generated during sulfide weathering process.  相似文献   

15.
Arsenic and fluoride in a loess aquifer in the central area of Argentina   总被引：3，自引：0，他引：3  
The objective of this study is to analyze the geochemical conditions associated with the presence of arsenic (As) and fluoride (F) in the phreatic aquifer of Coronel Moldes, in the central sector of the Argentine Chacopampean plain. The studied aquifer is composed of silty sand sediments of aeolian origin, typically loess-like sediments. The geochemical composition of water varies from sodium bicarbonate to sodium sulfate-chloride water. As contents range from low concentrations, below detection level, to 250 μg/l. High values of F (up to 12 mg/l) were recorded. A high As–F correlation was found (R 2 = 0.84). The pH varied from 7.31 to 8.85 and the nitrates reached concentrations up to 200 mg/l, indicating an oxidant environment. The highest values of As and F agreed with sodium bicarbonate waters as well as with the highest values of pH recorded. There was a high correlation between As and F− as well as between As and the Na/Ca ratio. The composition and texture of loess, low permeability and hydraulic gradients together with the geochemical features of sodium bicarbonate waters are proper conditions for the mobilization of As and F in groundwater in the central area of Argentina.  相似文献   

16.
Arsenic concentrations surpassing potability limit of 10 μg/L in the groundwater supplies of an extensive area in the Duero Cenozoic Basin (central Spain) have been detected and the main sources of arsenic identified. Arsenic in 514 samples of groundwater, having mean values of 40.8 μg/L, is natural in origin. Geochemical analysis of 553 rock samples, assaying arsenic mean values of 23 mg/kg, was performed. Spatial coincidence between the arsenic anomaly in groundwater and the arsenic lithogeochemical distribution recorded in the Middle Miocene clayey organic-rich Zaratan facies illustrates that the rocks of this unit are the main source of arsenic in groundwater. The ferricretes associated to the Late Cretaceous–Middle Miocene siliciclastics also constitute a potential arsenic source. Mineralogical study has identified the presence of arsenic in iron oxides, authigenic pyrite, manganese oxides, inherited titanium–iron oxides, phyllosilicates and organomineral compounds. Arsenic mobilization to groundwater corresponds to arsenic desorption from iron and manganese oxides and from organic matter.  相似文献   

17.
The influx of Sr responsible for increase in marine Sr has been attributed to rise of Himalaya and weathering of the Himalayan rocks. The rivers draining Himalaya to the ocean by the northern part of the Indian sub-continent comprising the Ganga Alluvial Plain (GAP) along with Central parts of the Himalaya and the northern part of the Indian Craton are held responsible for the transformation of Sr isotopic signature. The GAP is basically formed by the Himalayan-derived sediments and serves as transient zone between the source (Himalaya) and the sink (Bay of Bengal). The Gomati River, an important alluvial tributary of the Ganga River, draining nearly 30,500 km2 area of GAP is the only river which is originating from the GAP. The river recycles the Himalayan-derived sediments and transport its weathering products into the Ganga River and finally to Bay of Bengal. 11 water samples were collected from the Gomati River and its intrabasinal lakes for measurement of Sr isotopic composition. Sr concentration of Gomati River water is about 335 μg/l, which is about five times higher than the world’s average of river water (70 μg/l) and nearly three times higher than the Ganga River water in the Himalaya (130 μg/l) The Sr isotopic ratios reported are also higher than global average runoff (0.7119) and to modern seawater (0.7092) values. Strong geochemical sediment–water interaction appearing on surface is responsible for the dissolved Sr isotopic ratios in the River water. Higher Sr isotopic rations found during post-monsoon than in pre-monsoon season indicate the importance of fluxes due to monsoonal erosion of the GAP into the Gomati River. Monsoon precipitation and its interaction with alluvium appear to be major vehicle for the addition of dissolved Sr load into the alluvial plain rivers. This study establishes that elevated 87Sr/86Sr ratios of the Gomati River are due to input of chemical weathering of alluvial material present in the Ganga Alluvial Plain.  相似文献   

18.
《Applied Geochemistry》1993,8(5):447-471
Ground water is the main source of domestic and public supply in the Carson River Basin. Ground water originates as precipitation primarily in the Sierra Nevada in the western part of Carson and Eagle Valleys, and flows down gradient in the direction of the Carson River through Dayton and Churchill Valleys to a terminal sink in the Carson Desert. Because radionuclides dissolved in ground water can pose a threat to human health, the distribution and sources of several naturally occurring radionuclides that contribute to gross-alpha and gross-beta activities in the study area were investigated. Generally, alpha and beta activities and U concentration increase from the up-gradient to down-gradient hydrographic areas of the Carson River Basin, whereas222Rn concentration decreases. Both226Ra and228Ra concentrations are similar throughout the study area. Alpha and beta activities and U concentration commonly exceed 100 pCi/l in the Carson Desert at the distal end of the flow system. Radon-222 commonly exceeds 2,000 pCi/l in the western part of Carson and Eagle Valleys adjacent to the Sierra Nevada. Radium-226 and228Ra concentrations are <5pCi/l. Four ground water samples were analyzed for210Po and one sample contained a high concentration of 21 pCi/l. Seven samples were analyzed for210Pb; six contained <3pCi/l and one contained 12 pCi/l. Thorium-230 was detected at concentrations of 0.15 and 0.20 pCi/l in two of four samples.Alpha-emitting radionuclides in the ground water originated from the dissolution of U-rich granitic rocks in the Sierra Nevada by CO2, oxygenated water. Dissolution of primary minerals, mainly titanite (sphene) in the granitic rocks, releases U to the water. Dissolved U is probably removed from the water by adsorption on Fe- and Mn-oxide coatings on fracture surfaces and fine-grained sediment, by adsorption on organic matter, and by coprecipitation with Fe and Mn oxides. These coated sediments are transported throughout the basin by fluvial processes. Thus, U is transported as dissolved and adsorbed species. A rise in the water table in the Carson Desert because of irrigation has resulted in the oxidation of U-rich organic matter and dissolution of U-bearing coatings on sediments, producing unusually high U concentration in the ground water.Alpha activity in the ground water is almost entirely from the decay of U dissolved in the water. Beta activity in ground water samples is primarily from the decay of40K dissolved in the water and ingrowth of238U progeny in the sample before analysis. Approximately one-half of the measured beta activity may not be present in ground water in the aquifer, but instead is produced in the sample after collection and before analysis. Potassium-40 is primarily from the dissolution of K-containing minerals, probably K-feldspar and biotite. Radon-222 is primarily from the decay of226Ra in the aquifer materials. Radium in the ground water is thought to be mainly from alpha recoil associated with the decay of Th in the aquifer material. Some Ra may be from dissolution (or desorption) or Ra-rich coatings on sediments.  相似文献   

19.
Historically, the arid conditions of La Rioja, Argentina have been the main controlling factor in its development. The shortage of surface water, which is fully used, makes groundwater a potential source for development. The government encouraged investment in early 1979, resulting in a 20-fold increase of groundwater extraction by 1998 (0.076–1.450 m3/s, respectively) to cover related needs of agriculture, industry and population growth. This extraction created unjustified uncertainties derived from negative results obtained in hydrological balances. However, a 0.5 m lowering of the water-table surface was experienced. A knowledge of groundwater functioning was required to establish a reliable frame of reference for development and, at the same time, to find possible scenarios of feasible economic activities in harmony with accessible water resources and aptitude of the environment. The flow regime was found to be composed of three main systems: a regional, an intermediate and several local. The intermediate system provides water for the extraction boreholes, and discharges naturally in Salina La Antigua. From the chemical perspective the intermediate system has three groundwater groups. Group I has an outstanding fluoride concentration (1.98–3.10 mg/l) defined to the north of the City of la Rioja and the highest temperature (26.8–33.0°C), the lowest lithium content (0.029–0.059 mg/l) and moderate arsenic (≤0.038 mg/l). Group II has the moderate arsenic content (≤0.38 mg/l) detected to the south of the City of La Rioja and high lithium (0.024–0.085 mg/l), Group III has the lowest TDS (456–931 mg/l) and arsenic (0.007–0.012 mg/l) and the highest lithium (0.067–0.141 mg/l). to A regional flow is represented by Group IV with one order of magnitude higher strontium (4.870 mg/l), lead (0.021 mg/l) and uranium (0.362 mg/l) content than the other groups. Results provide evidence to eliminate several well-established hydro-myths such as “the boreholes are getting dry” and “boreholes are getting saline water”. The aquifer (granular Tertiary and Quaternary material) thickness (≈750m) was defined with the aid of the geological framework, geothermometers and Modflow modelling. The aquifer extent extends far beyond the limits of the study area. Several economic activities were found to be feasible with available groundwater resources and without bordening the environment (fish farming, bottled-water marketing, SPA activities and farming of endangered species).  相似文献   

20.
Environmental geochemistry of high arsenic groundwater at Hetao plain was studied on the basis of geochemical survey of the groundwater and a core sediment. Arsenic concentration in groundwater samples varies from 76 to 1093 μg/L. The high arsenic groundwater mostly appears to be weakly alkaline. The concentrations of NO3− and SO42− are relatively low, while the concentrations of DOC, NH4+, dissolved Fe and sulfide are relatively great. Analysis of arsenic speciation in 21 samples shows that arsenic is present in the solution predominantly as As(III), while particulate arsenic constitutes about 10% of the total arsenic. Methane is detected in five samples with the greatest content being 5107 μg/L. The shallow aquifer in Hangjinhouqi of western Hetao plain is of strongly reducing condition. The arsenic content in 23 core sediment samples varies from 7.7 to 34.6 mg/kg, with great value in clay and mild clay layer. The obvious positive relationship in content between Fe2O3, Mn, Sb, B, V and As indicates that the distribution of arsenic in the sediments may be related to Fe and Mn oxides, and the mobilization of Sb, B and V may be affected by similar geochemical processes as that of As.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号