共查询到20条相似文献，搜索用时 31 毫秒
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Groundwater extraction is rampant in many developing countries and urban areas whereas the natural recharge is decreasing due to covering of Earth's surface for various developmental activities. This leads to declining levels of groundwater and deterioration in groundwater quality. Artificial recharge with rain water harvesting techniques offers an excellent scope to arrest this degradation. This paper presents a study that analyzes the influence of rain water harvesting (RWH) on groundwater storage and quality. Chennai City, India is selected as study area, as major RWH implementation has taken place during 2002–2003 due to Government legislation. Preliminary analysis of groundwater levels were done spatially and temporally. Groundwater table contours were drawn using the GIS software for pre‐ (1999–2000) and post‐RWH (2009–2010) periods. The groundwater levels follow a decreasing trend before implementation of RWH where as a positive increasing trend takes place after construction of RWH structures. “Groundwater Estimation Committee (GEC)” norms of Government of India were used to estimate the change in storage during pre‐ and post‐RWH periods, which are found to be 1.76 × 106 and 32.77 × 106 m3, respectively. The results show that the implementation of RWH has increased the groundwater storage considerably. Also, the influence of RWH on groundwater quality is found to be encouraging in some parts of the studied area. 相似文献
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Dissolved high molecular weight organic substances, like humic substances, can be characterized with regard to their molecular weight distribution using gel filtration chromatography (GFC). In addition, the adsorption properties, for example on activated carbon, can be described, if the substances are separated by hydrophobic interaction chromatography (HIC) in different fractions using a chromatographic column with a hydrophobic matrix. The retention time (Rt) of single chemical substances in this column can be used to characterize the hydrophobicity or hydrophility of each compound as well as of the high molecular weight organic matter. The hydrophobic interaction between the matrix of the column and the dissolved chemical compounds also depends on the hydrophobicity of the gel and the composition of the eluent. Relations between retention times, log P-coefficients (octanol/water partition) and K-values of isotherms on activated carbon (Freundlich equation) were found. 相似文献
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利用核磁共振方法探查岩溶水 总被引：19，自引：4，他引：15
核磁共振（ＮＭＲ）找水方法是目前唯一直接找水的物探新方法,该方法可以探查各种类型的地下水。本文仅论述了在岩溶发育区常规电阻率方法找水时遇到的地质干扰。ＮＭＲ找水方法的原理,仪器的组成,并以实例说明了ＮＭＲ找水方法探查岩溶水的效果。 相似文献
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利用核磁共振方法探查基岩裂隙水 总被引：10，自引：0，他引：10
基岩裂隙水是我国分布最为广泛的地下水类型之一。本文阐述了基岩裂隙水的特点：含水层产状不规则、其赋存空间介质不均匀、同一含水层埋深不同、地下水运动状态复杂等。这些特殊的地质、地球物理特征,给常用的物探找水方法带来许多困难。本文通过对直接找水的新方法一核磁共振（ＮｕｃｌｅａｒＭａｇｎｅｔｉｃ Ｒｅｓｏｎａｎｃｅ,缩写为ＮＭＲ）测深与间接找水的电阻率测深的对比分析,论述了ＮＭＲ测深直接找水的实质。并以实例说明了ＮＭＲ测深在探查基岩裂隙水中的应用效果。 相似文献
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Seasonal and spatial dynamics of the concentrations of major ions, biogenic elements, organic matter, and microelements in Gusinoe Lake water are studied. The economic activity on lake coast has caused an increase in the concentrations of sulfate, sodium, and biogenic and organic matter in areas subject to direct technogenic impact. Lake areas subject to different technogenic impacts were found to differ in water mineralization and pH and the concentrations of microelements. The concentrations of Mo and Sr in lake water are 12–14 and 2–4 times greater than Russian MACs for water bodies used for fishery, respectively. 相似文献
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Water flow in the soil–root–stem system was studied in a flooded riparian hardwood forest in the upper Rhine floodplain. The study was undertaken to identify the vertical distribution of water uptake by trees in a system where the groundwater is at a depth of less than 1 m. The three dominant ligneous species (Quercus robur, Fraxinus excelsior and Populus alba) were investigated for root structure (vertical extension of root systems), leaf and soil water potential (Ψm), isotopic signal (18O) of soil water and xylem sap. The root density of oak and poplar was maximal at a depth of 20 to 60 cm, whereas the roots of the ash explored the surface horizon between 0 and 30 cm, which suggests a complementary tree root distribution in the hardwood forest. The flow density of oak and poplar was much lower than that of the ash. However, in the three cases the depth of soil explored by the roots reached 1·2 m, i.e. just above a bed of gravel. The oak roots had a large lateral distribution up to a distance of 15 m from the trunk. The water potential of the soil measured at 1 m from the trunk showed a zone of strong water potential between 20 and 60 cm deep. The vertical profile of soil water content varied from 0·40 to 0·50 cm3 cm?3 close to the water table, and 0·20 to 0·30 cm3 cm?3 in the rooting zone. The isotopic signal of stem water was constant over the whole 24‐h cycle, which suggested that the uptake of water by trees occurred at a relatively constant depth. By comparing the isotopic composition of water between soil and plant, it was concluded that the water uptake occurred at a depth of 20 to 60 cm, which was in good agreement with the root and soil water potential distributions. The riparian forest therefore did not take water directly from the water table but from the unsaturated zone through the effect of capillarity. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Variations in the key indices of the chemical composition of surface waters are studied in a region where these waters are polluted by mining plant wastes. The forms of metals migration and their distribution in the bottom deposits of watercourses are examined. The possible steps for reducing the pollution of water in a watercourse are discussed. 相似文献
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Biosorption using activated sludge biomass (ASB) as a potentially sustainable technology for the treatment of wastewater containing different metal ions (Cd(II), Pb(II) and Zn(II)) was investigated. ASB metal uptake clearly competed with protons consumed by microbial biomass compared with control tests with non‐activated sludge biomass. Biosorption tests confirmed maximum exchange between metal ions and protons at pH 2.0–4.5. It was revealed by the study that the amount of metal ions released from the biomass increased with biomass sludge concentration. The result showed that maximum absorption of metal ions was observed for Cd(II) at pH 3.5, Pb(II) at pH 4.0, and pH 4.5 for Zn(II) ions. The maximum absorption capacities of ASB for Cd(II), Pb(II) and Zn(II) were determined to be 59.3, 68.5 and 86.5%, respectively. The biosorption of heavy metals was directly proportional to ASB stabilization corresponding to a reduction in heavy metals in the order of Cd < Pb < Zn. The order of increase of biosorption of metal ions in ASB was Zn(II) < Pb(II) < Cd(II), and this was opposite to that of non active sludge. The results indicate that ASB is a sustainable tools for the bioremediation of Cd(II), Pb(II) and Zn(II) ions from industrial sludge and wastewater treatment plants. 相似文献
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J. Cruz-Sanjulián M. Olías M. del Valle J.C. Rubio 《Ground Water Monitoring & Remediation》1992,12(3):188-194
In July 1988, hydrocarbons were detected in wells in the urban area of Albolote, near Granada, Spain, near the border of the "Vega de Granada" alluvial aquifer. According to available hydrogeological data, the contamination was attributed to leaks in the underground pipelines of a nearby (300m) industrial factory, where the loss of 40,000 to 50,000 liters of gasoline had been detected some weeks before. A complete hydrogeological investigation was then undertaken, involving, among other techniques: (a) an inventory of the existing wells in the area; (b) the preparation of piezometric maps; (c) the application of electrical geophysical methods; (d) the drilling of piezometers and new pumping wells between the urbanized area and the leak point; (e) the improvement of the pluviometric and piezometric control by the installation of a pluviograph and several limnigraphs; (f) the sampling, initially daily and finally weekly, in a 20-well observation network, also used for piezometric control; and (g) the geostatistical study of the analytical data. The contamination plume, extended in the direction of the flow lines, has a length of 500m and a width of less than 50m, and appears to have occurred mainly in a paleochannel. Hydrocarbons (1600 liters) were recovered by pumping and by using absorbent blankets, as well as by a gas and liquid suction method. Hydrocarbon concentrations have continuously decreased. However, sporadic increases, associated with rainfall, have been observed suggesting the presence of retained hydrocarbons in the unsaturated zone. The rate of decrease in hydrocarbon concentrations has currently slowed, particularly in the less affected zone. As a means of activating the cleaning up of the unsaturated zone, an artificial recharging method has been designed. 相似文献
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E. Aguilera G. Chiodini R. Cioni M. Guidi L. Marini B. Raco 《Journal of Volcanology and Geothermal Research》2000,97(1-4)
A geochemical survey carried out in November 1993 revealed that Lake Quilotoa was composed by a thin (14 m) oxic epilimnion overlying a 200 m-thick anoxic hypolimnion. Dissolved CO2 concentrations reached 1000 mg/kg in the lower stratum. Loss of CO2 from epilimnetic waters, followed by calcite precipitation and a consequent lowering in density, was the apparent cause of the stratification.The Cl, SO4 and HCO3 contents of Lake Quilotoa are intermediate between those of acid–SO4–Cl Crater lakes and those of neutral-HCO3 Crater lakes, indicating that Lake Quilotoa has a ‘memory’ of the inflow and absorption of HC1- and S-bearing volcanic (magmatic) gases. The Mg/Ca ratios of the lake waters are governed by dissolution of local volcanic rocks or magmas, but K/Na ratios were likely modified by precipitation of alunite, a typical mineral in acid–SO4–Cl Crater lakes.The constant concentrations of several conservative chemical species from lake surface to lake bottom suggest that physical, chemical and biological processes did not have enough time, after the last overturn, to cause significant changes in the contents of these chemical species. This lapse of time might be relatively large, but it cannot be established on the basis of available data. Besides, the lake may not be close to steady state. Mixing of Lake Quilotoa waters could presently be triggered by either cooling epilimnetic waters by 4°C or providing heat to hypolimnetic waters or by seismic activity.Although Quilotoa lake contains a huge amount of dissolved CO2 (3×1011 g), at present the risk of a dangerous limnic eruption seems to be nil even though some gas exsolution might occur if deep lake waters were brought to the surface. Carbon dioxide could build up to higher levels in deep waters than at present without any volcanic re-awakening, due to either a large inflow of relatively cool CO2-rich gases, or possibly a long interval between overturns. Periodical geochemical surveys of Lake Quilotoa are, therefore, recommended. 相似文献
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Keith E. Schilling 《水文研究》2007,21(18):2415-2424
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A lumped water balance model was used to derive a monthly water storage series in the Salado–Juramento southern basin, for the period 1954–1986. The evapotranspiration term was estimated using the Bouchet's complementary relationship. Different evapotranspiration formulas following the concepts of potential evapotranspiration and wet environmental evapotranspiration were used. The regional average groundwater levels and the specific yield were used to tune Bouchet's equation. The extrapolation of the water storage series to a secular period (1901–2002) was achieved using a synthetic annual discharge series. The water storage was deficient for most of the century, i.e. more than 60 years; nevertheless in the last 30 years, the system recovers half of the water previously lost. The singular spectral analysis showed that a significant low‐frequency signal is present in the water storage and precipitation series. The main cause of water storage variability would be given by precipitation, in spite of the vast anthropogenic changes on the basin. Anthropogenic effects would be reflected in the river discharges, where no significant signal is detected before 1970; however, an annual signal is insinuated after that year. The conclusions of this work could be different if we only looked at the 1954–1986 period. The results of that period suggest that the basin is primarily accumulating water instead of being mainly in deficit. Thus, here we demonstrated the importance of the secular analysis to illustrate the complete basin behaviour. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Josip Rubinić 《水文科学杂志》2013,58(10):1908-1924
AbstractVrana Lake in Dalmatia is a karstic kryptodepression connected to the nearby sea through the karstic subsoil and a canal. Due to interactions with the sea, lake water salinity increases greatly during severe dry periods, seriously endangering the ecosystem. Trend analysis (1961–2010) reveals a decrease in precipitation and surface inflow, but an increase in air temperature, and in sea and lake water levels. Lake inflow and water losses are only partially monitored. Average annual inflow from the monitored part of the catchment is 1722 m3 s-1, but total inflow is significantly greater; the average difference between total inflow and cumulative water losses is 3072 m3 s-1. The paper uses modelling to evaluate total inflow into the lake system, taking into consideration projected climate changes/variations till 2100 from the RegCM3 and ALADIN climate models. The analysis indicates marked decrease in discharge values by the end of this century, by as much as 60%.
Editor Z.W. Kundzewicz 相似文献
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Jatin Srivastava Dinesh Shukla Vishal Chand Ram Naraian Harish Chandra Anant R. Nautiyal 《洁净——土壤、空气、水》2010,38(8):771-774
The presence of arsenic (As) in water is of great public concern. Arsenic exists in three common valence states viz., As(0) metalloid arsenic, As(III) (arsenite) and As(V) (arsenate). Arsenite [As(III)] is the most toxic form among arsenicals which, predominates in anaerobic conditions, generally in flooded soils and in the water with high BOD. Experiments were conducted to investigate the effect of As(III) on the mycorrhization in vetiver (Vetiveria zizanioides (L.) Nash) grass in hydroponics. Studies showed significant alteration in the mycorrhizal colonization in the roots of vetiver exposed to higher concentrations of As(III) starting from 1.0, 2.0, 3.0, 4.0 to 5.0 mg/L prepared in 5% Hoagland nutrient solution without addition of phosphate ions. Considerable reduction in the mycorrhizal intensity (M) was observed in all the treatment sets as compared to the control suggesting a negative impact of the As(III) on the mycorrhizal association. Simultaneously, the study also showed that, As(III) is toxic to the vetiver plants having mycorrhizal association however plants with non‐mycorrhizal (cleansed) roots were found to be able to survive for a longer period exposed to As(III). 相似文献