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Groundwater

About: Groundwater is a(n) research topic. Over the lifetime, 59360 publication(s) have been published within this topic receiving 1051258 citation(s). The topic is also known as: ground water & underground water.

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Open accessJournal ArticleDOI: 10.1016/S0883-2927(02)00018-5
Pauline Smedley1, David G. Kinniburgh1Institutions (1)
Abstract: The range of As concentrations found in natural waters is large, ranging from less than 0.5 μg l−1 to more than 5000 μg l−1. Typical concentrations in freshwater are less than 10 μg l−1 and frequently less than 1 μg l−1. Rarely, much higher concentrations are found, particularly in groundwater. In such areas, more than 10% of wells may be ‘affected’ (defined as those exceeding 50 μg l−1) and in the worst cases, this figure may exceed 90%. Well-known high-As groundwater areas have been found in Argentina, Chile, Mexico, China and Hungary, and more recently in West Bengal (India), Bangladesh and Vietnam. The scale of the problem in terms of population exposed to high As concentrations is greatest in the Bengal Basin with more than 40 million people drinking water containing ‘excessive’ As. These large-scale ‘natural’ As groundwater problem areas tend to be found in two types of environment: firstly, inland or closed basins in arid or semi-arid areas, and secondly, strongly reducing aquifers often derived from alluvium. Both environments tend to contain geologically young sediments and to be in flat, low-lying areas where groundwater flow is sluggish. Historically, these are poorly flushed aquifers and any As released from the sediments following burial has been able to accumulate in the groundwater. Arsenic-rich groundwaters are also found in geothermal areas and, on a more localised scale, in areas of mining activity and where oxidation of sulphide minerals has occurred. The As content of the aquifer materials in major problem aquifers does not appear to be exceptionally high, being normally in the range 1–20 mg kg−1. There appear to be two distinct ‘triggers’ that can lead to the release of As on a large scale. The first is the development of high pH (>8.5) conditions in semi-arid or arid environments usually as a result of the combined effects of mineral weathering and high evaporation rates. This pH change leads either to the desorption of adsorbed As (especially As(V) species) and a range of other anion-forming elements (V, B, F, Mo, Se and U) from mineral oxides, especially Fe oxides, or it prevents them from being adsorbed. The second trigger is the development of strongly reducing conditions at near-neutral pH values, leading to the desorption of As from mineral oxides and to the reductive dissolution of Fe and Mn oxides, also leading to As release. Iron (II) and As(III) are relatively abundant in these groundwaters and SO4 concentrations are small (typically 1 mg l−1 or less). Large concentrations of phosphate, bicarbonate, silicate and possibly organic matter can enhance the desorption of As because of competition for adsorption sites. A characteristic feature of high groundwater As areas is the large degree of spatial variability in As concentrations in the groundwaters. This means that it may be difficult, or impossible, to predict reliably the likely concentration of As in a particular well from the results of neighbouring wells and means that there is little alternative but to analyse each well. Arsenic-affected aquifers are restricted to certain environments and appear to be the exception rather than the rule. In most aquifers, the majority of wells are likely to be unaffected, even when, for example, they contain high concentrations of dissolved Fe.

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Topics: Arsenic contamination of groundwater (53%), Groundwater flow (53%), Groundwater (53%) ...read more

6,106 Citations


Open accessBook
C.A.J. Appelo1, Diederik Jan PostmaInstitutions (1)
01 Jan 1993-
Abstract: Groundwater geochemistry is an interdisciplinary science concerned with the chemistry in the subsurface environment. The chemical composition of groundwater is the combined result of the quality of water that enters the groundwater reservoir and reactions with minerals and organic matter of the aquifer matrix may modify the water quality. Apart from natural processes as controlling factors on the groundwater quality, in recent years the effect of pollution, such as nitrate from fertilizers and acid rain, also influences the groundwater chemistry. Due to the long residence time of groundwater in the invisible subsurface environment, the effect of pollution may first become apparent tens to hundreds of years afterwards. A proper understanding of the processes occurring in aquifers is required in order to predict what the effect of present day human activities will be on that scale. This book presents a comprehensive and quantitative approach to the study of groundwater quality. Practical examples of application are presented throughout the text.

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Topics: Groundwater pollution (71%), Groundwater flow (65%), Groundwater (64%) ...read more

4,619 Citations


Open accessBook
23 Jul 1997-
Abstract: The Environmental Isotopes Environmental Isotopes in Hydrogeology Stable Isotopes: Standards and Measurement Isotope Ratio Mass Spectrometry Radioisotopes Isotope Fractionation Isotope Fractionation (a), Enrichment (e), and Separation (D) Tracing the Hydrological Cycle Craig's Meteoric Relationship in Global Fresh Waters Partitioning of Isotopes Through the Hydrological Cycle Condensation, Precipitation, and the Meteoric Water Line A Closer Look at Rayleigh Distillation Effects of Extreme Evaporation Precipitation The T - d18O Correlation in Precipitation Local Effects on T - d18O Ice Cores and Paleotemperature Groundwater Recharge in Temperate Climates Recharge in Arid Regions Recharge from River-Connected Aquifers Hydrograph Separation in Catchment Studies Groundwater Mixing Tracing the Carbon Cycle Evolution of Carbon in Groundwaters Carbonate Geochemistry Carbon-13 in the Carbonate System Dissolved Organic Carbon Methane in Groundwaters Isotopic Composition of Carbonates Chapter 6. Groundwater Quality Sulphate, Sulphide and the Sulphur Cycle Nitrogen Cycles in Rural Watersheds The "Fuhrberger Feld" Study Source of Chloride Salinity Landfill Leachates Degredation of Chloro-organics and Hydrocarbon Sensitivity of Groundwater to Contamination Summary of Isotopes in Contaminant Hydrology Identifying and Dating Modern Groundwaters The "Age" of Groundwater Stable Isotopes Tritium in Precipitation Dating Groundwaters with Tritium Groundwater Dating with 3H -3He Chlorofluorocarbons (CFCs) Thermonuclear 36Cl Detecting Modern Groundwaters with 85Kr Submodern Groundwater Age Dating Old Groundwaters Stable Isotopes and Paleogroundwaters Groundwater Dating with Radiocarbon Correction for Carbonate Dissolution Some Additional Complications to 14C Dating 14C Dating with Dissolved Organic Carbon (DOC) Case Studies for 14C dating with DOC and DIC Chlorine-36 and Very Old Groundwater The Uranium Decay Series Water-Rock Interaction Mechanisms of Isotope Exchange High Temperature Systems Low Temperature Water-Rock Interaction Strontium Isotopes in Water and Rock Isotope Exchange in Gas-Water Reactions High pH Groundwaters-The Effect of Cement Reactions Field Methods for Sampling Groundwater Water in the Unsaturated Zone Precipitation Gases Geochemistry References Index Each chapter has Problems sections.

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3,689 Citations


Open accessBook
01 Jan 1979-
Abstract: Keywords: Ecoulement souterrain Reference Record created on 2004-09-07, modified on 2016-08-08

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Topics: Groundwater (52%)

2,878 Citations


Open accessBook
01 Jan 1990-
Abstract: The Origin of Porosity and Permeability. Ground-Water Movement. Main Equations of Flow, Boundary Conditions, and Flow Nets. Ground Water in the Basin Hydrologic Cycle. Hydraulic Testing: Models, Methods, and Applications. Ground Water as a Resource. Stress, Strain, and Pore Fluids. Heat Transport in Ground-Water Flow. Solute Transport. Principles of Aqueous Geochemistry. Chemical Reactions. Colloids and Microorganisms. The Equations of Mass Transport. Mass Transport in Natural Ground-Water Systems. Mass Transport in Ground-Water Flow: Geologic Systems. Introduction to Contaminant Hydrogeology. Modeling the Transport of Dissolved Contaminants. Multiphase Fluid Systems. Remediation: Overview and Removal Options. In Situ Destruction and Risk Assessment. Answers to Problems. Appendices. References. Index.

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Topics: Groundwater (51%), Hydrogeology (50%)

2,845 Citations


Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202285
20213,336
20203,390
20193,129
20183,143
20172,902

Top Attributes

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Topic's top 5 most impactful authors

Lakshmanan Elango

93 papers, 3.5K citations

Yanxin Wang

72 papers, 2.2K citations

Kazi Matin Ahmed

50 papers, 4K citations

Kristine Walraevens

45 papers, 757 citations

Peter G. Cook

43 papers, 1.9K citations

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