Iron-manganese oxides

The waste organic acids dissolved carbonate minerals, alumino-silicate minerals, and iron/manganese-oxide coatings on the primary minerals in the injection zone. 

Lion, L. W., Altmann, R. S. and Leckie, J. O. (1982). Trace-metal adsorption characteristics of estuarine particulate matter evaluation of contributions of iron/ manganese oxide and organic surface coatings, Environ. Sci. Technol., 16, 660-666. 

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... 

Table 18.1 Average Compositions of the Earth s Upper Continental Crust, Shale, Iron-Manganese Oxides, Phosphorite, and Various Types of Marine Sediments (All in Units of ppm. Unless Noted otherwise), along with Seawater and a Hydrothermal Vent Solution from the East Pacific Rise (both in Units of 10 g L ). 

Iron-manganese oxides Hydrogenous precipitates composed of iron and manganese oxides. Most of the metals are hydrothermal in origin. 

Nodules Mineral precipitates, such as iron-manganese oxides and glauconites, that form as roundish lumps. 

For standards, see Table 1 (Iron, manganese oxide pigments Methods of analysis Natural, specification Sienna, specification and Umber, specification ). 

Shan and Chen [32] reported that various proportions of metals released from exchangeable, carbonate-bound iron, manganese oxide-bound and organic-bound fractions were readsorbed onto the other solid geochemical phases during sequential extractions. 

It appears unlikely, that lanthanides are mobile. They appear to remain in situ as insoluble precipitates or bound to insoluble materials formed during weathering, as for example, clay minerals [139], iron, manganese oxide minerals [133] and possible soil organic materials. 

K. Ehrensberger, A. Frei, P. Kuhn, H.R. Oswald, and P. Hug, Comparative experimental investigations on the water-splitting reaction with iron oxide Fei-yO and iron manganese oxides (Fei-xMnx) i-yO, Solid State Ionics, 78 151-160 (1995). 

Anion adsorption and then the exchange of anions mainly takes place on the protonated surface sites of silicates and other oxides (e.g., iron, manganese oxides) and hydroxides, as well as on the positive functional group (e.g., protonated amino groups) of humic substances. It is directed by electrostatic forces. The degree of anion exchange of rocks and soils is usually much less than that of cation exchange. 

Weisweiler, W. Environmentally friendly denitrification catalysts based on iron/manganese oxide/sulfate for use in simultaneous denitration and desulphurization of waste gases in a circulating fluidized bed, DECHEMA Monogr., 118 (Katalyse), pp. 81-103 (1989). 

Step 1. Extraction of the acid soluble fraction (i.e., carbonates) with CH3COOH Step 2. Extraction of the reducible fraction (i.e., iron/manganese oxides) with hydroxyl amine hydrochloride... 

Metal contamination of soils is primarily due to the application of sewage sludge, manure, phosphate fertilizers, atmospheric deposition, and traffic emissions. The most common heavy metal ions found in soils are Zn, Cu, Ni, Pb, Cr, and Cd. As mentioned earlier (see Section 6.3.1.4), sequential extraction techniques can differentiate among the metal forms in a soil, typically the acid soluble fraction (e.g., carbonates), the reducible fraction (e.g., iron/manganese oxides), and the ox-idizable fraction (i.e., metals in low oxidation states). 

Step 2. Metals bound to iron/manganese oxides are unstable under reducing conditions. Changes in the redox potential ( ),) could induce the dissolution of these oxides and could also release adsorbed trace metals. 

Stripped Matrix. For use in all LRRs except V, W, X, and Y. A layer starting within 15 cm (6 in.) of the soil surface in which iron/manganese oxides or organic matter have been stripped from the matrix, exposing the primary base color of soil materials. The stripped areas and translocated oxides or organic matter form a faint diffnse splotchy pattern of two or more colors. The stripped zones are 10% or more of the volnme they are rounded and approximately 1-3 cm (0.5-1 in.) in diameter (Figure 3.25). 

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