Manganese oxides enrichments

Two types of metal-rich hydrogenous deposits are formed on the seafloor iron-manganese oxides and polymetallic sulfides. The iron-manganese oxides have been deposited as nodules, sediments, and crusts. They are enriched in various trace elements, such as manganese, iron, copper, cobalt, nickel, and zinc, making them a significant repository for some of these metals. Most of the metals in the polymetallic sulfides are of hydrothermal origin. These sulfides have been deposited as metalliferous sediments aroimd hydrothermal systems and as rocks that infill cracks within former... 

The mechanism of adsorption has been extensively studied in order to evaluate its importance in the regulation of the concentration of certain species in natural waters. In particular, adsorption on iron and manganese oxides has been proposed as the chemical mechanism which controls the concentration of some trace metals in the world s oceans (], 2) and the enrichment of certain trace metals in ferromanganese nodules ( 3). ... 

Ferromanganese nodules and seamount crusts are characterized by distinct alternating layers of iron oxides and manganese oxides in addition to other components such as aluminosilicates (shale), CFA, and sometimes biogenic barite and carbonates in seamount crusts. Iron-oxide phases are enriched in elements that exist in normal seawater mainly as hydroxyl and carbonate complexes of tri- to pentavalent cations (e.g.. As, B, Bi, In, Ir, Rh, REEs, Y, Ti, Th, U, Zr, Hf, Nb, and Ta), oxyanions (e.g., P, Re, Ru, Os, S, Se, Te, V, and W), and divalent cations... 

The high capacity of manganese oxides for the sorption of cations leads to an enrichment of manganese-rich sediments in a number of economically valuable transition metals, particularly copper, nickel, and cobalt. However, the exact mechanism of the incorporation of these metals remains controversial. For example, R. G. Burns and M. Burns (1977a) maintained that these elements substitute within the lattice of the manganese minerals, whereas Glasby (1974)... 

The process of enrichment of trace metals in these non-biologically produced sediments is probably adsorption to the surface of iron and manganese oxides that form on virtually all particle surfaces in the ocean. This is also the process that forms manganese nodules in vast areas of deep-ocean sediments. Manganese nodules actually accrete on the sea floor at a rate of approximately 1 mm per million years, primarily in areas where there is little accumulation of CaCOs and opal-rich sediments, e.g. the vast red clay provinces of the North Pacific Ocean. Manganese nodules are enriched in the same metals that are found authigenically in the sediments (Table 12.4) to such an extreme... 

Humus can hold copper in concentrations of up to 1% of its weight. Indeed some bogs through which copper-enriched artesian waters flow naturally contain up to 100,000 iigig copper probably in their humus as Cu +, as CuOH ", and as occlusions in iron or manganese oxides, and as mixed oxides. It was therefore found that copper applied to the surface soil did not move downward into groundwater except when a single application of 1500... 

It has been observed that organic particles settling through the hypolimnion of lakes become enriched with phosphorus (Gachter and Mares, 1985). The mechanism by which this occurs is still not completely clear, but seems to be related to adsorption of phosphate to mineral surfaces produced by iron-and manganese-oxidizing bacteria (Hupfer... 

Sun Y-K, Lee M-J, Yoon CS et al (2012) The role of AIF3 coatings in improving electrochemical cycling of Li-enriched nickel-manganese oxide electrodes for Li-ion batteries. Adv Mater 24(9) 1192-1196... 

Zinc ligands are soluble in neutral and acidic solutions, so that zinc is readily transported in most natural waters (USEPA 1980, 1987), but zinc oxide, the compound most commonly used in industry, has a low solubility in most solvents (Elinder 1986). Zinc mobility in aquatic ecosystems is a function of the composition of suspended and bed sediments, dissolved and particulate iron and manganese concentrations, pH, salinity, concentrations of complexing ligands, and the concentration of zinc (USEPA 1980). In freshwater, zinc is most soluble at low pH and low alkalinity 10 mg Zn/L of solution at pH 6 that declines to 6.5 at pH 7, 0.65 at pH 8, and 0.01 mg/L at pH 9 (Spear 1981). Dissolved zinc rarely exceeds 40 pg/L in Canadian rivers and lakes higher concentrations are usually associated with zinc-enriched ore deposits and anthropogenic activities. Marine... 

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