Inorganic Geochemistry and Redox Dynamics in Bank Filtration Settings
24 May 2011-Environmental Science & Technology (American Chemical Society)-Vol. 45, Iss: 12, pp 5079-5087
TL;DR: This review presents the four main geochemical processes relevant for inorganic geochemistry, with a focus on iron (Fe) and manganese (Mn), during bank filtration: reduction near the bank, oxidation near the production well, carbonate dissolution, and sorption to aquifer materials.
Abstract: Bank filtration induces flow of surface water through a hydraulically connected aquifer by excess pumping from a production well in the aquifer. This review presents the four main geochemical processes relevant for inorganic geochemistry, with a focus on iron (Fe) and manganese (Mn), during bank filtration: reduction near the bank, oxidation near the production well, carbonate dissolution, and sorption to aquifer materials. Physical and transport processes affect these geochemical processes and influence the redox state of the infiltrate. The presence of Fe and Mn in bank infiltrate is directly related to its redox status and can necessitate drinking water treatment after extraction. Long-term, in situ sequestration of Fe and Mn requires precipitation of oxide or carbonate solids, since a sorption front can breakthrough at the production well.
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01 Jan 2012
216 citations
Cites background from "Inorganic Geochemistry and Redox Dy..."
...Examples of these types of studies are available for many areas of Europe and the United States (Farnsworth and Hering, 2011), including Ohio (Sheets and others, 2002), Missouri (Kelly, 2002; Kelly and Rydlund, 2006), and Oregon (McCarthy and others, 1992)....
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...Natural “bank filtration” of surface-water contaminants as they move from a stream to a pumped well involves geochemical and biological processes that remove nutrients, organic carbon, and microbes from the contaminated water (National Research Council, 2008; Farnsworth and Hering, 2011)....
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TL;DR: The study highlights the efficiency of RBF for water quality improvement as a pre-treatment step for drinking water production, however, it also shows the very persistent behavior of various compounds in groundwater.
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TL;DR: The depth profiles of As and SO4 and the conservative tracers Cl/Br, δ(18)O, and δH show that the As in Pleistocene groundwater beneath deep paleo-channels is relict and does not arise from migration downward of As-polluted groundwater in overlying aquifers.
Abstract: in groundwaters from 145 wells across central West Bengal, India, those from Pleistocene aquifers at depths >70 m beneath paleo-interfluves contain <10 μg/L As. Pleistocene aquifers beneath deep paleo-channels typically host groundwaters containing 10–100 μg/L As at depths between 120 and 180 m. The depth profiles of As and SO4 and the conservative tracers Cl/Br, δ18O, and δ2H show that the As in Pleistocene groundwater beneath deep paleo-channels is relict and does not arise from migration downward of As-polluted groundwater in overlying aquifers. We postulate that the As was liberated in situ by reduction of minimal iron oxyhydroxides in the gray Pleistocene sands by organic matter infiltrating from riverbeds during late Pleistocene or earliest Holocene times. Mitigation of the widespread As-pollution in shallow aquifers through exploitation of deep Pleistocene aquifers would improve if guided by an understanding of the distribution of buried paleo-channels and paleo-interfluves and the knowledge that A...
79 citations
TL;DR: Results from this study indicate land surface-soil-aquifer connections play an important role in producing elevated manganese concentrations in groundwater used for human consumption.
Abstract: Chemical data from 43 334 wells were used to examine the role of land surface-soil-aquifer connections in producing elevated manganese concentrations (>300 μg/L) in United States (U.S.) groundwater. Elevated concentrations of manganese and dissolved organic carbon (DOC) in groundwater are associated with shallow, anoxic water tables and soils enriched in organic carbon, suggesting soil-derived DOC supports manganese reduction and mobilization in shallow groundwater. Manganese and DOC concentrations are higher near rivers than farther from rivers, suggesting river-derived DOC also supports manganese mobilization. Anthropogenic nitrogen may also affect manganese concentrations in groundwater. In parts of the northeastern U.S. containing poorly buffered soils, ∼40% of the samples with elevated manganese concentrations have pH values < 6 and elevated concentrations of nitrate relative to samples with pH ≥ 6, suggesting acidic recharge produced by the oxidation of ammonium in fertilizer helps mobilize manganese. An estimated 2.6 million people potentially consume groundwater with elevated manganese concentrations, the highest densities of which occur near rivers and in areas with organic carbon rich soil. Results from this study indicate land surface-soil-aquifer connections play an important role in producing elevated manganese concentrations in groundwater used for human consumption.
79 citations
TL;DR: The distributions of Fe, Mn, As, V, Mo, U, PO(4), and δ(18)O in groundwater reflect subsurface sedimentology and sources of water and show that organic matter from in situ sanitation may contribute to driving reduction.
Abstract: To reveal what controls the concentration and distribution of possibly hazardous (Mn, U, Se, Cd, Bi, Pb) and nonhazardous (Fe, V, Mo, PO4) trace elements in groundwater of the Bengal delta, we mapped their concentrations in shallow groundwater (<60 mbgl) across 102 km2 of West Bengal. Only Mn is a potential threat to health, with 55% of well water exceeding 0.3 mg/L, the current Indian limit for drinking water in the absence of an alternate source, and 75% exceeding the desirable limit of 0.1 mg/L. Concentrations of V are <3 μg/L. Concentrations of U, Se, Pb, Ni, Bi, and Cd, are below WHO guideline values.The distributions of Fe, Mn, As, V, Mo, U, PO4, and δ18O in groundwater reflect subsurface sedimentology and sources of water. Areas of less negative δ18O reveal recharge by sources of evaporated water. Concentrations of Fe, As, Mo, and PO4 are high in palaeo-channel groundwaters and low in palaeo-interfluvial groundwaters. Concentrations of U, V, and Mn, are low in palaeo-channel groundwaters and high i...
61 citations
References
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TL;DR: In this paper, an analytical procedure involving sequential chemicai extractions was developed for the partitioning of particulate trace metals (Cd, Co, Cu, Ni, Pb, Zn, Fe, and Mn) into five fractions: exchangeable, bound to carbonates, binding to Fe-Mn oxides and bound to organic matter.
Abstract: An analytical procedure involving sequential chemicai extractions has been developed for the partitioning of particulate trace metals (Cd, Co, Cu, Ni, Pb, Zn, Fe, and Mn) into five fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter, and residual. Experimental results obtained on replicate samples of fluvial bottom sediments demonstrate that the relative standard deviation of the sequential extraction procedure Is generally better than =10%. The accuracy, evaluated by comparing total trace metal concentrations with the sum of the five Individual fractions, proved to be satisfactory. Complementary measurements were performed on the Individual leachates, and on the residual sediments following each extraction, to evaluate the selectivity of the various reagents toward specific geochemical phases. An application of the proposed method to river sediments is described, and the resulting trace metal speciation is discussed.
10,518 citations
City College of New York1, University of Wisconsin-Madison2, University of Michigan3, Swiss Federal Institute of Aquatic Science and Technology4, University of Hong Kong5, University of New Hampshire6, Griffith University7, Southern Cross University8, University of Washington9, University of Western Australia10
TL;DR: The first worldwide synthesis to jointly consider human and biodiversity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts is presented.
Abstract: Protecting the world’s freshwater resources requires diagnosing threats over a broad range of scales, from global to local. Here we present the first worldwide synthesis to jointly consider human and biodiversity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts. We find that nearly 80% of the world’s population is exposed to high levels of threat to water security. Massive investment in water technology enables rich nations to offset high stressor levels without remedying their underlying causes, whereas less wealthy nations remain vulnerable. A similar lack of precautionary investment jeopardizes biodiversity, with habitats associated with 65% of continental discharge classified as moderately to highly threatened. The cumulative threat framework offers a tool for prioritizing policy and management responses to this crisis, and underscores the necessity of limiting threats at their source instead of through costly remediation of symptoms in order to assure global water security for both humans and freshwater biodiversity.
5,401 citations
Book•
01 Jan 1980
TL;DR: In this article, Berner developed the mathematical theory of early diagenesis, introducing a general diagenetic equation and discussing it in terms of each major diagenetics process, including diffusion, compaction, pore-water flow, burial advection, bioturbation, adsorption, radioactive decay and especially chemical and biochemical reactions.
Abstract: Diagenesis refers to changes taking place in sediments after deposition. In a theoretical treatment of early diagenesis, Robert Berner shows how a rigorous development of the mathematical modeling of diagenetic processes can be useful to the understanding and interpretation of both experimental and field observations. His book is unique in that the models are based on quantitative rate expressions, in contrast to the qualitative descriptions that have dominated the field. In the opening chapters, the author develops the mathematical theory of early diagenesis, introducing a general diagenetic equation and discussing it in terms of each major diagenetic process. Included are the derivations of basic rate equations for diffusion, compaction, pore-water flow, burial advection, bioturbation, adsorption, radioactive decay, and especially chemical and biochemical reactions. Drawing on examples from the recent literature on continental-margin, pelagic, and non-marine sediments, he then illustrates the power of these diagenetic models in the study of such deposits. The book is intended not only for earth scientists studying sediments and sedimentary rocks, but also for researchers in fields such as radioactive waste disposal, petroleum and economic geology, environmental pollution, and sea-floor engineering.
2,849 citations
TL;DR: The physiological characteristics of Geobacter species appear to explain why they have consistently been found to be the predominant Fe(III)- and Mn(IV)-reducing microorganisms in a variety of sedimentary environments.
2,633 citations
TL;DR: The crystal structures for todorokite and birnessite, two of the more common Mn oxide minerals in terrestrial deposits and ocean nodules, were determined by using powder x-ray diffraction data and the Rietveld refinement method.
Abstract: Manganese oxide minerals have been used for thousands of years—by the ancients for pigments and to clarify glass, and today as ores of Mn metal, catalysts, and battery material. More than 30 Mn oxide minerals occur in a wide variety of geological settings. They are major components of Mn nodules that pave huge areas of the ocean floor and bottoms of many fresh-water lakes. Mn oxide minerals are ubiquitous in soils and sediments and participate in a variety of chemical reactions that affect groundwater and bulk soil composition. Their typical occurrence as fine-grained mixtures makes it difficult to study their atomic structures and crystal chemistries. In recent years, however, investigations using transmission electron microscopy and powder x-ray and neutron diffraction methods have provided important new insights into the structures and properties of these materials. The crystal structures for todorokite and birnessite, two of the more common Mn oxide minerals in terrestrial deposits and ocean nodules, were determined by using powder x-ray diffraction data and the Rietveld refinement method. Because of the large tunnels in todorokite and related structures there is considerable interest in the use of these materials and synthetic analogues as catalysts and cation exchange agents. Birnessite-group minerals have layer structures and readily undergo oxidation reduction and cation-exchange reactions and play a major role in controlling groundwater chemistry.
1,498 citations