Download or read book The Impact of Small Organic Acids on Iron and Manganese Mineral Transformations and the Fate of Trace Metals written by Elaine Denise Flynn and published by . This book was released on 2018 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Iron and manganese oxides are ubiquitous in soils and sediments and play a critical role in the geochemical distribution of trace elements and heavy metals through adsorption and coprecipitation. At redox interfaces, biogeochemical processes generate conditions with coexisting dissolved Fe(II) and solid-phase Fe(III). In such systems, Fe(II) induces the recrystallization of iron oxides through coupled mineral growth and dissolution due to electron transfer as oxidative adsorption of Fe(II) and reductive dissolution of Fe(III) occur. Aqueous Mn(II) adsorption onto Mn(III/IV) oxides also likely involves oxidation although likely through different mechanisms than that of the Fe system because of the potential for Mn(II)-Mn(IV) comproportionation reactions. During reactions between reduced and oxidized forms of Fe and Mn, trace metals may be redistributed among the mineral bulk, mineral surface, and aqueous solution. Many metals, including Ni and Zn, are important micronutrients but are also toxic at higher concentrations. It is important to identify the processes controlling the fate and availability of trace metals in the environment and this requires understanding the behavior and stability of Fe and Mn oxides. Small organic acids, produced as root exudates or by decomposition of organic matter in aerated soils, may potentially alter reactions involving Fe and Mn oxide minerals and trace metals through a series of cooperative or competitive processes: solution complexation, ternary surface complexation, surface site competition, ligand-promoted dissolution, and reductive dissolution. The effects of organic acids on trace metal fate in such systems is unclear because these processes may involve both trace metals and Fe or Mn oxides, and multiple processes may co-occur. The main objective of this dissertation is to determine how organic acids interacting with Fe and Mn oxides affect structural transformations of these minerals, including dissolution and recrystallization, and the resulting impact on trace metals micronutrient and contaminant fate. Three main research projects were conducted to meet this objective. First, the cooperative and competitive interactions between oxalate and Ni during adsorption to Fe oxide minerals were identified. Next, the effects of oxalate on Ni incorporation into and release from Fe oxides at pH 4 and 7 was investigated during Fe(II)-promoted recrystallization of these minerals. Finally, reductive transformations of layered Mn oxides by oxalate, citrate, and 4-hydroxybenzoate at pH 4, 5.5, and 7 were characterized as well as the associated changes in Ni and Zn adsorption extent and mechanisms. The addition of oxalate in macroscopic adsorption studies suppresses Ni uptake by goethite and hematite at pH 7. Aqueous speciation modelling indicates that this is dominantly the result of oxalate complexing and solubilizing Ni. Comparison of the Ni surface coverage to the concentration of free (uncomplexed) Ni2+ in solution suggests that oxalate also alters Ni adsorption affinity. Extended X-ray absorption fine structure and attenuated total reflectance Fourier transform infrared spectroscopies indicate that these changes in binding affinity are due to the formation of Ni-oxalate ternary surface complexes. When Ni is initially structurally-incorporated into hematite and goethite, oxalate and dissolved Fe(II) each promote the release of Ni to aqueous solution at pH 4 and 7. With the co-addition of both species, the effects on Ni release are synergistic at pH 7 but inhibitory at pH 4. This suggests that cooperative and competitive interactions vary with pH. In contrast, oxalate suppresses Ni incorporation into goethite and hematite during Fe(II)-induced recrystallization. Mn oxides may undergo redox and structural changes which can weaken trace metal binding and promote metal mobility. The conditions studied to date involve Mn(II) and are most similar to those found at redox interfaces which are limited in spatial extent in nature. Aging e-MnO2 and hexagonal birnessite in the presence of small organic acids was investigated using powder X-ray diffraction and X-ray absorption fine structure spectroscopic measurements. Organic acids caused partial Mn reduction but did not substantially alter the phyllomanganates sheet structure nor result in transformations to Mn(III) oxyhydroxides or mixed-valent minerals. All organic acids were fully consumed, producing solid-phase Mn(II) and Mn(III) as well as dissolved Mn(II), the latter favored under acidic pH conditions. Citrate caused the greatest reduction, with its oxidation products continuing to react and near-complete mineralization observed at pH 4. These redox reactions improved stacking of the phyllomanganate sheets for e-MnO2 at pH 7 and enhanced capping of vacancy sites by cations occurred for both minerals under all conditions studied. As a result of this mineral alteration, Ni and Zn adsorption behaviors were also modified. Net metal uptake did not change substantially at pH 7 where nearly all of the Ni and Zn in the system were adsorbed to the mineral surface. However, at pH 4, adsorption of Ni and Zn decreased in the presence of the organic acids. Ni adsorption mechanisms transitioned from binding above vacancy sites to at sheet edges in the presence of citrate and 4-hydroxybenzoate, while oxalate increased binding above and in vacancy sites; citrate inhibited Ni incorporation into vacancies. Zn adsorption also transitioned to binding at weaker sites on the particle edges. The adsorption behaviors of Ni and Zn suggest that during reaction with organic acids, phyllomanganate mineral reactivities towards metals are altered by organic acids via a decrease in the vacancy content of Mn oxides. This work improves our understanding of the effect of Fe and Mn oxides in soils and aquatic systems on micronutrient availability and heavy metals sequestration. Oxalate largely enhances trace metal mobility through multiple processes occurring in solution and on Fe oxide surfaces. Similarly, phyllomanganates structural changes in the presence of oxalic, citric, and 4-hydroxybenzoate alter the reactivity of Mn oxides through Mn reduction and subtle structural changes. Overall, this dissertation demonstrates that complex interactions at Fe and Mn oxide surfaces with organic acids must be considered when evaluating micronutrient availability and contaminant sequestration in the environment.

Download or read book Ion Interactions at the Mineral water Interface During Biogeochemical Iron and Manganese Cycling written by Margaret A. G. Hinkle and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The biogeochemical cycling of iron and manganese involves the reductive dissolution and oxidative precipitation of Fe(III) and Mn(IV/III) oxides. Biogenic Fe(III) and Mn(IV/III) oxides are often characterized by high surface areas and therefore high sorptive capacities. As a result, these minerals can substantially alter the chemistry of natural waters and the availability of micronutrients in soils and sediments by scavenging trace metals. Recent research indicates that the adsorption of aqueous Fe(II) onto Fe(III) oxides involves oxidative adsorption, electron transfer, and subsequent reductive dissolution at another surface site [a process collectively referred to as 'electron transfer-atom exchange' (ET-AE)]. Aqueous Mn(II) adsorption onto Mn(IV/III) oxides likely also involves oxidation, but because of the potential for Mn(II) Mn(IV) comproportionation reactions and the accessibility of nearly all atoms in Mn(IV/III) oxide sheets to reaction with aqueous solution, aqueous Mn(II)-solid Mn(IV/III) interactions are expected to differ substantially from the analogous Fe system. These complex interactions between reduced and oxidized forms of Fe (and Mn) occur at redox interfaces and can exert substantial effects on trace metal fate. These processes may, in turn, be affected by ions common in natural systems. The main objective of this dissertation is to determine how interactions between ions commonly present during biogeochemical Fe or Mn cycling in natural systems [e.g., phosphate, sulfate, Ni, Zn, Fe(II), or Mn(II)] alter one another's interactions with Fe and Mn oxide surfaces. This research specifically seeks to (1) identify the mechanisms through which the oxoanions phosphate and sulfate alter Fe(II) adsorption onto Fe oxides; (2) determine how oxoanion-Fe(II) interactions alter trace metal partitioning between the mineral surface, bulk mineral structure, and aqueous phase; (3) characterize the effect of Mn(II) on phyllomanganate sheet structures; and (4) examine the effect of Mn(II) on trace metal sorption on phyllomanganates. Macroscopic adsorption edges show that Fe(II) cooperatively co-adsorbs with sulfate and phosphate on Fe(III) oxide surfaces. Both attenuated total reflectance Fourier transform infrared spectroscopy and surface complexation modeling indicate that this cooperative adsorption behavior arises from a combination of ternary complexation and electrostatic interactions. The formation Fe(II)-oxoanion ternary complexes suggests that processes associated with Fe(II) Fe(III) ET-AE reactions may be altered in the presence of oxoanions, depending on the stability and identity of the ternary complex that forms. The effect of these oxoanions on one such process, trace metal repartitioning, was investigated in detail. Sulfate and, to a larger degree, phosphate suppress Ni cycling through hematite during Fe(II)-catalyzed recrystallization by altering Ni adsorption, structural incorporation, and release back into solution. Conversely, Ni cycling through goethite is unaffected or enhanced by phosphate and sulfate. This dissertation also investigated Mn(II) effects on phyllomanganate structure and the fate of associated trace metals. Powder X-ray diffraction and X-ray absorption fine structure spectroscopic measurements indicate that Mn(II) causes distortion of the sheet structure of Mn(IV/III) oxides and alters sheet stacking at low pH, but has a minimal effect on phyllomanganate structures at circumneutral pH. As a result, Ni and Zn adsorption mechanisms on phyllomanganates are altered in the presence of aqueous Mn(II) at pH 4, but exhibit few changes at pH 7. The Ni and Zn adsorption behaviors with aqueous Mn(II) suggests that Mn(II) alters phyllomanganate reactivities by decreasing phyllomanganate vacancy content. These results emphasize the importance of understanding adsorbate interactions in systems with coexisting reduced and oxidized Fe or Mn, as under such conditions Fe and Mn oxide minerals undergo dynamic structural transformations. Trace metal uptake and partitioning between Fe oxide surfaces can be altered in systems with appreciable amounts of phosphate or sulfate (e.g., riparian zones, estuaries, or marine sediments). The complex interactions at iron oxide surfaces must be considered when evaluating trace metal fate at redox interfaces or interpreting trace metal proxies in the rock record to reconstruct ancient water compositions. The Mn(II)-induced phyllomanganate structural changes observed here suggest a relationship between water composition and the reactivity of Mn oxides as adsorbent materials. The identified phyllomanganate restructuring may also modify the capacity of Mn oxides to serve as oxidants of inorganic and organic compounds in aquatic systems. This dissertation highlights the complex structural and chemical processes that occur via cooperative and competitive interactions of ion at iron and manganese oxide surfaces.

Download or read book Diet and Health written by National Research Council and published by National Academies Press. This book was released on 1989-01-01 with total page 765 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diet and Health examines the many complex issues concerning diet and its role in increasing or decreasing the risk of chronic disease. It proposes dietary recommendations for reducing the risk of the major diseases and causes of death today: atherosclerotic cardiovascular diseases (including heart attack and stroke), cancer, high blood pressure, obesity, osteoporosis, diabetes mellitus, liver disease, and dental caries.

Download or read book Biomineralization written by H. Catherine W. Skinner and published by . This book was released on 1992 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Iron manganese biomineralization; Iron minerals in surface environments; Manganese minerals in surface environments; Crystal structures of manganese oxide minerals; Microbial biomineralization of iron and manganese; Microbial oxidation of organic matter coupled to the reduction of fe (III) and Mn(IV) oxides; Microbial accumulation of iron and manganese in different aquatic environments: an electron optical study; Magnetotactic bacteria: biomineralization, ecology, sediment magnetism, environmental indicator; Production of iron sulfide minerals by magnetotactic bacteria in sulfidic environments; Manganese oxides producec by fungal oxidation of manganese from siderite and rhodochrosite; Biogenic ferrihydrite: effect of B-thalassemia/ hemoglobin E disease onthe structure of ferrihydrite present in ferritins isolated from iron-loaded human heart and spleen tissue; Manganese nodules and microbial oxidation of manganese in the huntley meadows wetland, Virginia, USA; Iron sulfidization in tidal marsh soils; Mineralogy of precipitates formed by the biogeochemical oxidation of Fe(II) in mine drainage; Natural iron precipitates in a mine retention pond near Jabiru, Northern Territory, Australia; Iron deposits and microorganisms in saline sulfidic soils with altered soil water regimes in South Australia; Transformations of iron, manganese and aluminium during oxidation of a sulfidic material from an acid sulfate soil; Deposition and accumulation of biogenic magnetite in low oxygen facies ...

Download or read book Introduction to Environmental Mineralogy written by Anhuai Lu and published by Springer Nature. This book was released on 2023-05-22 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the environmental property of minerals including mineralogical record of environmental changes, mineralogical influence on the environmental quality, mineralogical evaluation of the environment, mineralogical processing of environmental pollutants and interaction between minerals and microbes. Understanding of the environmental property of minerals is a good supplement to the traditional concept of “mineral”. By demonstrating plenty of case studies with easy-to-understand figures and tables, this book introduces the environmental effects of interaction between minerals and microbes, physiological and ecological effects of biomineralization, reductive precipitation property of iron sulfide minerals, photocatalytic reduction property of sphalerite, photocatalytic oxidation property of rutile, tubular structure property of chrysotile, tunnel structure property of K-feldspar tetrahedron, tunnel structure property of cryptomelane octahedron, nano property of cryptomelane, crystallization property of jarosite, interaction between semiconducting minerals and microbes, pathological mineralization of human body, mineralogical processing of inorganic pollutants, mineralogical degradation of organic pollutants, mineralogical purification of smoke-type pollutants, mineralogical evaluation of soil environmental quality, mineralogical prevention and control of waste pollutants and mineralogical processing of mine tailings. The book is written for environmental mineralogist as well as postgraduates majoring in environmental science.

Download or read book Occurrence and Distribution of Iron Manganese and Selected Trace Elements in Ground Water in the Glacial Aquifer System of the Northern United States written by and published by . This book was released on 2009 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved trace elements, including iron and manganese, are often an important factor in use of ground water for drinking-water supplies. Concentrations of these trace elements can very over several orders of magnitude across local well networks as well as across regions of the United States.

Download or read book Effect of PH and Organic Acids on Nitrogen Transformations and Metal Dissolution in Soils written by Minhong Fu and published by . This book was released on 1989 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Acid Oxides Upon Desulfurization in the Iron manganese System written by Miles Benjamin Royer and published by . This book was released on 1948 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1991 with total page 884 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Impact of Organic Acids and Mineral Properties on Microbial Iron Oxide Reduction written by Juliane Braunschweig and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transactions written by and published by . This book was released on 1968 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1989 with total page 1310 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Low Temperature Geochemistry written by Tu Guangzhi and published by VSP. This book was released on 1996-12 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-temperature geochemistry -- a 'hot topic' in geochemistry at present -- deals with geological and chemical processes and the geochemical evolution of elements in nature below 200C, including the geochemical behaviour of elements in the processes of their extraction, remobilization, transport and mineralization at room temperature and below 0C. This book focuses on the low-temperature geochemical behaviour of precious metals, REE, some individual dispersed elements and some non-metallic elements and their minergenesis at low-temperatures. The book deals with the following topics: 1) geochemistry of selected low-temperature deposits or prospects (horizons); 2) geochemistry of elements during diagenesis, buried metamorphism and low-grade metamorphism; 3) remobilization, transport and precipitation of some ore-forming elements under low-temperature conditions; 4) water/rock interactions in low-temperature open systems

Download or read book Effects of Root derived Organic Acids on Metal Speciation in Soil Solution and Bioavailability written by Carlos Alberto Bissani and published by . This book was released on 2000 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Trace Element Cycling During Iron II activated Recrystallization of Iron III Oxide Minerals written by Andrew James Frierdich and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biogeochemical iron cycling initiates secondary abiotic reactions between aqueous Fe(II) and Fe(III) oxide minerals, which results in dynamic recrystallization via simultaneous Fe(II) oxidative adsorption and Fe(III) reductive dissolution. Fe(III) oxide minerals are abundant in soils, sediments, and groundwater systems, and often control the fate and transport of trace elements. A robust understanding of their reactivity with Fe(II) and how associated trace elements are affected during Fe(II)-activated recrystallization is required to predict the effect of biogeochemical processes on contaminant fate and micronutrient availability. The main objective of the research presented in this dissertation is to characterize how Fe(II)-activated recrystallization of iron oxide minerals affects the cycling and fate of associated trace elements. The specific foci are to: 1) obtain a general description of redox-inactive trace element cycling through iron oxide minerals, 2) examine the chemical controls on net trace element release from goethite and hematite, 3) explore surface passivation and trace element release inhibition during Fe(II)-activated recrystallization of iron oxides containing insoluble elements, and 4) determine the fate of redox-sensitive metals that are structurally incorporated in iron oxides during reaction with Fe(II). Compositional measurements and spectroscopic results show that Ni is cycled through the minerals goethite and hematite during Fe(II)-activated recrystallization. Adsorbed Ni becomes progressively incorporated into the minerals while Ni pre-incorporated into iron oxides is released to solution. The kinetics of Ni and Zn release to solution are primarily controlled by the amount of Fe(II) sorption. Furthermore, these structurally-incorporated trace elements are mobilized from iron oxides into fluids without net iron reduction. The Fe(II)-activated release of Ni and Zn from goethite and hematite is substantially inhibited when the insoluble elements Al, Cr, and Sn are co-substituted within the mineral structures. Incorporation of Al into goethite substantially decreases the amount of Fe atom exchange between aqueous Fe(II) and Fe(III) in the mineral and, consequently, the amount of Ni release from the structure. This implies that the mechanism for trace element release inhibition, following substitution of insoluble elements, is a decrease in the amount of mineral recrystallization. Reaction of Cu(II)-, Co(III)-, and Mn(III, IV)-substituted goethite and hematite with Fe(II) results in the reduction and release of Cu, Co, and Mn to solution. This work suggests that important proxies for ocean composition on the early Earth may be invalid, identifies new processes that affect micronutrient availability, contaminant transport, and the distribution of redox-inactive trace elements in natural and engineered systems, and shows that redox-sensitive elements are susceptible to reduction and release to solution despite being incorporated within a stable mineral structure. Furthermore, this work illustrates that naturally occurring iron oxides that contain insoluble impurities are less susceptible to Fe(II)-activated recrystallization and exhibit a greater retention of trace elements and contaminants than pure mineral phases. These discoveries demonstrate that, in the presence of Fe(II), iron oxide minerals are not passive surfaces that merely adsorb ions but rather their entire volume equilibrates with fluids. Such advances expand our view on the potential impacts of iron cycling on the fate of trace elements and contaminants.

Download or read book Research Study on the Effect of Dispersion Settling and Resedimentation on Migration of Chemical Constituents During Open water Disposal of Dredged Materials written by Kenneth Y. Chen and published by . This book was released on 1976 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Remediation Engineering written by Suthan S. Suthersan and published by CRC Press. This book was released on 1996-10-24 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: In many cases, the application of in situ technologies evolved as a necessity from a cost perspective. However, the basic understanding of the mechanisms and theory behind these technologies was treated as a "black box." Although we have seen some tremendous successes in the application of remediation technologies over the past several years, we have also seen many cases in which a technology has been incorrectly or inappropriately applied. In most cases, this misapplication has been the result of a poor understanding of the basic concepts and mechanisms behind the technologies. Without proper understanding, the potential for misapplication of technologies remains a serious economic and technical threat.