Download or read book Reactivity of Manganese Oxide Minerals with Soil Organic Matter and Lead written by Christopher J. Matocha and published by . This book was released on 2000 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geochemical and Hydrological Reactivity of Heavy Metals in Soils written by H. Magdi Selim and published by CRC Press. This book was released on 2003-03-26 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydrological and geochemical interactions between clay minerals and organic matter in soils directly influence the reaction, behavior, and mobility of heavy metals in soils. Geochemical and Hydrological Reactivity of Heavy Metals in Soils is one of few books that comprehensively illustrates this cause-and-effect relationship. It highlights anal

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 Some Reactions of Manganese with Montmorillonite and Soil Organic Matter written by Ramon Antonio Rosell and published by . This book was released on 1967 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book INTERACTIONS BETWEEN METAL OXIDES AND OR NATURAL ORGANIC MATTER AND THEIR INFLUENCE ON THE OXIDATIVE REACTIVITY OF MANGANESE DIOXIDE written by Saru Taujale and published by . This book was released on 2015 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mn oxides have high redox potentials and are known to be very reactive, rendering many contaminants susceptible to degradation via oxidation. Although Mn oxides typically occur as mixtures with other metal oxides (e.g., Fe, Al, and Si oxides) and natural organic matter (NOM) in soils and aquatic environments, most studies to date have studied the reactivity of Mn oxides as a single oxide system. This study, for the first time, examined the effect of representative metal oxides (Al2O3, SiO2, TiO2, and Fe oxides) and NOM or NOM-model compounds (Aldrich humic acid (AHA), Leonardite humic acid (LHA), pyromellitic acid (PA) and alginate) on the oxidative reactivity of MnO2, as quantified by the oxidation kinetics of triclosan (a widely used phenolic antibacterial agent) as a probe compound. The study also examined the effect of soluble metal ions released from the oxide surfaces on MnO2 reactivity. In binary oxide mixtures, Al2O3 decreased the reactivity of MnO2 as a result of both heteroaggregation and complexation of soluble Al ions with MnO2. At pH 5, the surface charge of MnO2 is negative while that of Al2O3 is positive resulting in intensive heteroaggregation between the two oxides. Up to 3.15 mM of soluble Al ions were detected in the supernatant of 10 g/L of Al2O3 at pH 5.0 whereas the soluble Al concentration was 0.76 mM in the mixed Al2O3 + MnO2 system at the same pH. The lower amount of soluble Al in the latter system is the result of Al ion adsorption by MnO2. The experiments with the addition of 0.001 to 0.1 mM Al3+ to MnO2 suspension indicated the triclosan oxidation rate constant decreased from 0.24 to 0.03 h-1 due to surface complexation. Fe oxides which are also negatively charged at pH 5 inhibited the reactivity of MnO2 through heteroaggregation. The concentration of soluble Fe(III) ions ( 4 mg-TOC/L or [alginate/PA] > 10 mg/L, a lower extent of heteroaggregation was also observed due to the negatively charged surfaces for all oxides. Similar effects on aggregation and MnO2 reactivity as discussed above were observed for ternary MnO2-Al2O3-NOM systems. HAs, particularly at high concentrations (2.0 to 12.5 mg-C/L), alleviated the effect of soluble Al ions on MnO2 reactivity as a result of the formation of soluble Al-HA complexes. Alginate and PA, however, did not form soluble complexes with Al ions so they did not affect the effect of Al ions on MnO2 reactivity. Despite the above observations, the amount of Al ions dissolved in MnO2+Al2O3+NOM mixtures was too low, as a result of NOMs adsorption on the surface to passivate oxide dissolution, to have a major impact on MnO2 reactivity. In conclusion, this study provided, for the first time, a systematical understanding of the redox activity of MnO2 in complex model systems. With this new knowledge, the gap between single oxide systems and complex environmental systems is much narrower so that it is possible to have a more accurate prediction of the fate of contaminants in the environment.

Download or read book Behavior of Metals in Soils written by Joan E. McLean and published by . This book was released on 1992 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Groundwater Geochemistry written by William J. Deutsch and published by CRC Press. This book was released on 2020-11-25 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Groundwater Geochemistry: Fundamentals and Applications to Contamination examines the integral role geochemistry play s in groundwater monitoring and remediation programs, and presents it at a level understandable to a wide audience. Readers of all backgrounds can gain a better understanding of geochemical processes and how they apply to groundwater systems. The text begins with an explanation of fundamental geochemical processes, followed by a description of the methods and tools used to understand and simulate them. The book then explains how geochemistry applies to contaminant mobility, discusses remediation system design, sampling program development, and the modeling of geochemical interactions. This clearly written guide concludes with specific applications of geochemistry to contaminated sites. This is an ideal choice for readers who do not have an extensive technical background in aqueous chemistry, geochemistry, or geochemical modeling. The only prerequisite is a desire to better understand natural processes through groundwater geochemistry.

Download or read book Plant Effects on Soil Manganese Availability written by Gnahoua Honore Godo and published by . This book was released on 1978 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quality Agriculture written by John Kempf and published by . This book was released on 2020-06-10 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: An increasing number of farmers and scientists believe the foundational ideas of mainstream agronomy are incomplete and unsound. Conventional crop production ignores biology in favor of chemical interventions, leading farmers to buy inputs they don't need. Fertilizer recommendations keep going up, pest pressure becomes more intense, pesticide applications are needed more often, and soil health continues to degrade. However, innovative growers and researchers are beginning to think differently about production agriculture systems. They have developed practices that regenerate soil and plant health and that deliver much better results than mainstream methods. Using these principles, growers are able to decrease fertilizer applications, reduce disease and insect pressure, hold more water in the soil, improve soil health, and grow crops that are more resilient to climatic extremes, increasing farm profitability immediately. As a leading agronomist and teacher, John Kempf has implemented regenerative agricultural systems on millions of acres across many different crop types and growing regions with his team at Advancing Eco Agriculture. In Quality Agriculture, John interviews a group of growers, consultants, and scientists who describe how to think and farm differently in order to produce exceptional results in the field. Their remarkable insights will challenge you, encourage you, and inspire gratitude and joy for the rewards of working with natural systems.

Download or read book Abiotic and Biotic formation of Manganese Oxides and Their Fate in Environmental Systems written by Haesung Jung and published by . This book was released on 2017 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt: Manganese (hydr)oxide (Mn (hydr)oxide) minerals are ubiquitous in aquatic and terrestrial environments. These minerals have high surface areas and are highly sorptive and redox active. From decades of accumulated knowledge about natural redox cycling, we have found that Mn (hydr)oxides play critical roles as electron donors and acceptors in elemental geochemical cycling and biological metabolisms in nature. Thus, Mn (hydr)oxides have garnered increasing interest to understand natural systems. Considering the variety of redox reactions with Mn (hydr)oxides in nature, it is also expected that there should be diverse pathways to form Mn (hydr)oxides through abiotic and biotic processes. Previous studies have focused on biotic oxidation and mineralization, and found that biotic processes are the dominant mechanism, with much faster oxidation of Mn2+ (aq) to Mn(IV) than observed in abiotic processes. Even in biotic processes, however, our understanding of the oxidation and formation mechanisms of Mn (hydr)oxides is limited. And not surprisingly, our understanding of the abiotic oxidation and formation of Mn (hydr)oxides is even more elusive. Therefore, further studies of oxidation of Mn2+ (aq) to Mn(IV) and consequent formation of Mn (hydr)oxides in both abiotic and biotic systems are necessary to reveal how nature forms current shapes of Mn (hydr)oxides, and uses them for natural redox reactions. Specifically, understanding the early nucleation mechanisms and kinetics of Mn (hydr)oxides is important because these nanoparticles can be starting points for bulk mineral formations of interest in both environmental and engineering applications. Therefore, in this dissertation, we have investigated the diverse oxidation and formation mechanisms of Mn (hydr)oxides in aqueous systems through both abiotic and biotic pathways. We have provided an advanced understanding of the Mn (hydr)oxide nucleation and phase transformation process by accomplishing three objectives.First, the nucleation mechanism and kinetics of Mn(OH)2 (s) nanoparticles on quartz surfaces and in solutions were elucidated under varied ionic strength (IS) and pH conditions. Here, we found that varied IS and pH conditions influence the kinetics of Mn(OH)2 (s) formation on quartz, and change in the structural match between Mn(OH)2 (s) and quartz. From this objective, we provided a new quantitative and qualitative understanding of the influence of IS and pH on Mn (hydr)oxide formation, and of the mechanisms of heterogeneous nucleation of Mn (hydr)oxides on quartz substrates.Second, the biomimetic oxidation of Mn2+ (aq) to Mn(III) and the subsequent biomineralization mechanism to [alpha]-Mn(III)OOH nanoparticles were studied using apoferritin, a protein produced by almost all living organisms, including bacteria, plants, and animals. The biotic processes of manganese oxidation by bacteria have been studied widely. However, in the literature, there are only limited explanations of how certain protein molecules mediate the formation of Mn (hydr)oxides inside the proteins' cavity. Using the colorimetric method, we analyzed the kinetics of [alpha]-MnOOH core formation under varied experimental conditions, and found that Mn2+ and OH- are rate-determining agents, with orders of reaction of 2 and 4, respectively. This new information on the protein-mediated oxidation and formation of Mn (hydr)oxide gives important insights into the mechanisms of protein-mediated oxidation and the formation of Mn (hydr)oxides in natural systems.Finally, we investigated the photochemically-assisted fast oxidation of Mn2+ (aq) and consequent formation of Mn(IV) oxides in inorganic abiotic systems. Even in the absence of organic matter and microorganisms, and contrary to prior reports, we found that Mn2+ (aq) is oxidized to Mn(IV) very rapidly under simulated sunlight. We observed Mn oxide nanoparticle formation and characterized the morphology and oxidation state change by reaction with a generated reactive oxygen species (ROS) source under simulated sunlight. The analyses of the oxidation state indicated the formation of Mn(IV) oxide, and in particular, of layered birnessite nanoparticles. We also found that in the presence of an inorganic ligand, pyrophosphate (PP), Mn (IV) oxide phase formation was enhanced and its structural change could be controlled by varying the concentration of PP. Elucidating the fast oxidation rate of Mn2+ (aq) into Mn(IV) oxides in inorganic abiotic systems, facilitated by ROS and a ligand, is a new and original contribution. Our results provide a novel, environmentally friendly, and facile synthetic pathway to make layered birnessite, which can be easily adapted by industry.The advanced findings of this dissertation research provide crucial insights into the redox reactions and nucleation of Mn (hydr)oxides in dynamic natural and engineered environmental systems. They can also help to design environmentally benign nanoparticle synthesis methods and to control the phase identities of Mn (hydr)oxides, promoting their utility in engineered applications, such as Li-ion battery cathodes and heavy metal remediation.

Download or read book Salt induced Release of Soil Manganese and Uptake by Sugar Beet written by Riaz Ahmad Khattak and published by . This book was released on 1986 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigative Strategies for Lead Source Attribution at Superfund Sites Associated with Mining Activities written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2017-12-01 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Superfund program of the US Environmental Protection Agency (EPA) was created in the 1980s to address human-health and environmental risks posed by abandoned or uncontrolled hazardous-waste sites. Identification of Superfund sites and their remediation is an expensive multistep process. As part of this process, EPA attempts to identify parties that are responsible for the contamination and thus financially responsible for remediation. Identification of potentially responsible parties is complicated because Superfund sites can have a long history of use and involve contaminants that can have many sources. Such is often the case for mining sites that involve metal contamination; metals occur naturally in the environment, they can be contaminants in the wastes generated at or released from the sites, and they can be used in consumer products, which can degrade and release the metals back to the environment. This report examines the extent to which various sources contribute to environmental lead contamination at Superfund sites that are near lead-mining areas and focuses on sources that contribute to lead contamination at sites near the Southeast Missouri Lead Mining District. It recommends potential improvements in approaches used for assessing sources of lead contamination at or near Superfund sites.

Download or read book Movement of Hazardous Substances in Soil Selected metals written by Emily D. Copenhaver and published by . This book was released on 1979 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Empirical Models of Pb and Cd Partitioning Using Data from 13 Soils Sediments and Aquifer Materials written by Nicholas T. Loux and published by . This book was released on 2005 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lead (Pb) and cadmium (Cd) are two of the most common toxicants found in contaminated environments. Because solubilization of these metallic elements from the solid phase can influence their fate, transport and bioavailability, the partitioning coefficient (Kd) for these metals between environmental solids and natural waters is a key parameter needed for assessing the risks posed by these two elements when present in environmental solids at elevated concentrations. In common with other ionizable contaminants, theoretical models applicable to all environments for assessing the partitioning behavior of Pb and Cd do not exist. Consequently, empirical partitioning models have been developed by the international technical research community. Using large datasets of Pb and Cd partitioning obtained from 13 aquifer materials, soils and sediments, two improved, commonly applicable, empirical models of extended accuracy and applicability were developed in this work.

Download or read book Movement of hazardous substances in soil written by Emily D. Copenhaver and published by . This book was released on 1979 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2004 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geological Survey Professional Paper written by and published by . This book was released on 1976 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: