Pub Date : 2005-07-15DOI: 10.1002/047147844X.GW301
E. Holzbecher
Classical papers by Badon Ghijben and Herzberg, dealing with the saltwater–freshwater interface in an unconfined coastal aquifers—are presented in some detail first, including the historical context. What follows is a discussion of the conditions that have to be fulfilled for the Ghijben–Herzberg equilibrium (GHE) to be valid. Moreover, generalized formulations and findings, which have been developed during the century, are presented. It is shown that the GHE can be a useful rule of a thumb for confined aquifers, for general two-phase fluid situations, for saltwater upconing below wells, and for situations without a sharp interface. The GHE can even be included successfully in computer models. Finally, a precursor of the classical papers is mentioned. Keywords: Ghyben–Herzberg equilibrium; water density; density-driven flow; sharp interface; seawater intrusion; saltwater upconing; coastal aquifer
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Pub Date : 2005-04-15DOI: 10.1002/047147844X.SW356
R. Viadero
Acid mine drainage (AMD) results when metal pyrites come in contact with water and/or air, to form dilute sulfuric acid. For instance, iron pyrite (FeS2) is the major iron-sulfur impurity found in mined earth, particularly in the eastern United States where coal mining is prevalent. Typically, AMD waters contain elevated concentrations of SO4, Fe, Mn, Al, and other metal ions. As an example, representative AMD water quality parameters from the Roaring Creek-Grassy Run Watershed, located in Elkins, West Virginia, include pH from 2.4 to 3.3, mineral acidities from 2.4 to 980 mg/L as CaCO3, dissolved iron between 35 and 260 mg/L, and sulfate concentrations from 190 to 740 mg/L. In contrast, copper and arsenic sulfide compounds associated with “hard rock” mining operations are common in the western United States; such compounds are generally much less prevalent in the east. In such instances, sulfide containing minerals such as pyrrhotite (FeS), arsenopyrite (FeAsS), and chalcopyrite (CuFeS2) can produce acidic drainage when oxidized. Keywords: acid mine drainage; AMD; acidity; alkalinity; cations; precipitation–dissolution; metal pyrite; sulfur; microbially mediated oxidation; carbonate equilibrium
{"title":"The Geochemistry of Acid Mine Drainage","authors":"R. Viadero","doi":"10.1002/047147844X.SW356","DOIUrl":"https://doi.org/10.1002/047147844X.SW356","url":null,"abstract":"Acid mine drainage (AMD) results when metal pyrites come in contact with water and/or air, to form dilute sulfuric acid. For instance, iron pyrite (FeS2) is the major iron-sulfur impurity found in mined earth, particularly in the eastern United States where coal mining is prevalent. Typically, AMD waters contain elevated concentrations of SO4, Fe, Mn, Al, and other metal ions. As an example, representative AMD water quality parameters from the Roaring Creek-Grassy Run Watershed, located in Elkins, West Virginia, include pH from 2.4 to 3.3, mineral acidities from 2.4 to 980 mg/L as CaCO3, dissolved iron between 35 and 260 mg/L, and sulfate concentrations from 190 to 740 mg/L. \u0000 \u0000 \u0000 \u0000In contrast, copper and arsenic sulfide compounds associated with “hard rock” mining operations are common in the western United States; such compounds are generally much less prevalent in the east. In such instances, sulfide containing minerals such as pyrrhotite (FeS), arsenopyrite (FeAsS), and chalcopyrite (CuFeS2) can produce acidic drainage when oxidized. \u0000 \u0000 \u0000Keywords: \u0000 \u0000acid mine drainage; \u0000AMD; \u0000acidity; \u0000alkalinity; \u0000cations; \u0000precipitation–dissolution; \u0000metal pyrite; \u0000sulfur; \u0000microbially mediated oxidation; \u0000carbonate equilibrium","PeriodicalId":190339,"journal":{"name":"Encyclopedia of Water","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114968730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-04-15DOI: 10.1002/047147844X.OC128
G. Nürnberg
Hypoxic conditions (dissolved oxygen, DO, concentration below saturation) are widely spread in freshwater and saline environments. Especially in recent years, anthropogenic impacts have led to severe increases in estuarine and coastal anoxia [e.g., Gulf of Mexico and European coast-lines]. Diaz describes 44 marine areas of moderate to severe hypoxia worldwide. Hypoxia and anoxia (lack of oxygen or zero concentration of DO) may even be more established in the freshwater environment, where it can occur naturally in lakes or not and where recent increases in organic and nutrient loading and changes in water flow have increased oxygen depletion in lakes, reservoirs, and large rivers. Keywords: quantification of anoxia and hypoxia; oxygen depletion; oxygen deficit; lakes; reservoirs; marine bays; oxygen standards or criteria or guidelines; TMDL-total maximum daily loads; climate change
{"title":"Quantification of Anoxia and Hypoxia in Water Bodies","authors":"G. Nürnberg","doi":"10.1002/047147844X.OC128","DOIUrl":"https://doi.org/10.1002/047147844X.OC128","url":null,"abstract":"Hypoxic conditions (dissolved oxygen, DO, concentration below saturation) are widely spread in freshwater and saline environments. Especially in recent years, anthropogenic impacts have led to severe increases in estuarine and coastal anoxia [e.g., Gulf of Mexico and European coast-lines]. Diaz describes 44 marine areas of moderate to severe hypoxia worldwide. Hypoxia and anoxia (lack of oxygen or zero concentration of DO) may even be more established in the freshwater environment, where it can occur naturally in lakes or not and where recent increases in organic and nutrient loading and changes in water flow have increased oxygen depletion in lakes, reservoirs, and large rivers. \u0000 \u0000 \u0000Keywords: \u0000 \u0000quantification of anoxia and hypoxia; \u0000oxygen depletion; \u0000oxygen deficit; \u0000lakes; \u0000reservoirs; \u0000marine bays; \u0000oxygen standards or criteria or guidelines; \u0000TMDL-total maximum daily loads; \u0000climate change","PeriodicalId":190339,"journal":{"name":"Encyclopedia of Water","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114729063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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