Mobility Of Manganese Research Articles

Environmental risks associated with aeration of a freshwater sediment exposed to mine drainage water

The study examined freshwater sediments from a pond receiving waters from an open-pit lignite quarry located in Europe's Black Triangle in the northern part of the Czech Republic. Sediments were studied with respect to chemical changes upon aeration to assess the risks associated with their acidification and release of toxic metals. Three types of sediments were sampled: orange precipitates of ferric oxides, underlying black anoxic material and brown clayey material from the original bottom of the pond. The experiment revealed that only black anoxic sediment presents environmental concerns upon aeration. Its redox potential rose steeply from –124 up to +412 mV within the first 50 h of aeration, afterwards, it increased only slowly and reached a finale value of +663 mV after 362 h of aeration. The redox changes were accompanied by sulphate production. Up to 97,037.8 mg of sulphate was released into the solution from 1 kg of the sediment. Consequently, the pH values dropped from 6.7 down to 3.3 within the first 50 h of aeration and reached a value of 2.7 at the end of the experiment. The decrease of pH values was followed by increased zinc and manganese mobility. Iron solubilisation was not continuous. An initial drop in iron mobility was followed by an increase, after which the mobility decreased again. This fluctuation reflected the changes in iron solubility depending on the oxidation state and pH changes in the sediment suspension.

Fractal analysis to discriminate between biotic and abiotic attacks on chalcopyrite and pyrolusite

In the present paper, a model describing release and mobility of copper and manganese in chalcopyrite and pyrolusite powders due to bacterial bioleaching, i.e. Thiobacillus ferrooxidans and Arthrobacter sp., is proposed. Sites where copper and manganese were released were examined by scanning electron microscopy (SEM). The resulting micrographs were scanned and submitted to a point by point fractal analysis to verify if a discrimination between biological and chemical attack could be established on the basis of the distribution of the fractional part of the fractal dimension over the whole surface. We demonstrate that such a method is able to discriminate among the different attacks.

The Importance of the Manganese‐Oxidizing Microorganism Metallogenium personatum for the Retention of Manganese in the Wahnbach Reservoir

AbstractThe retention of manganese in the water of the Wahnbach reservoir was determined in mass balance calculations. The retention properties for manganese drastically decreased after the phosphorus elimination plant was taken into service. Processes controlling the distribution and mobility of manganese in the reservoir were based on the results of tests conducted to evaluate the role of the microorganism Metallogenium personatum. A substantial retention of manganese in the Wahnbach reservoir was found to be dependent on the presence of this planktonic manganese‐oxidizing bacterium. The test results clearly indicate the importance of Metallogenium spec. as catalyst in the removal and oxidation of dissolved Mn(II).

Lithium Intercalation into Layered LiMnO2

Recently Armstrong and Bruce reported a layered modification of lithium manganese oxide, , isostructural with obtained by ion exchange from synthesized in air is characterized by x‐ray diffraction and by electrochemical insertion and extraction of lithium in a series of voltage ranges between 1.5 and 4.5 V relative to a lithium electrode. During cycling, voltage plateaus at 3.0 and 4.0 V vs., Li develop, indicating that the material is converted from its original layered structure to a spinel structure. This finding is confirmed by x‐ray diffraction. Contrary to expectations based on thermodynamics, insertion of larger amounts of lithium leads to a more complete conversion. We suggest that a relatively high mobility of manganese leaves Li and Mn randomly distributed in the close‐packed oxygen lattice after a deep discharge. This isotropic Mn distribution can relatively easily relax to the Mn distribution characteristic of spinels whereas the anisotropic distribution characteristic of layered structures is not reformed when excess lithium is extracted.

Cycling of Iron and Manganese in a Riparian Wetland

Iron and manganese are common contaminants in waste streams from coal bed methane production and in acid mine drainage resulting from surface mining of coal and metallic ore deposits (Henrot and Wieder, 1990). Wetlands, both natural and artificial, have been proposed as natural filters to remove these and other contaminants from waste waters. There is currently inadequate knowledge of the specific mechanisms that control the mobility of iron and manganese in wetland systems, and of the long-term ability of wetlands to retain these metals. Iron and manganese can exist in waste streams both as dissolved ions or as finely divided particles (colloids). In aerobic environments, dissolved iron and manganese are removed from water primarily through chemical oxidation, although some uptake of metals by wetland vegetation can also occur (deWet et al., 1990). The mobility of iron and manganese can be enhanced in aerobic environments by complexation with bidentate organic ligands such as oxalate (Graustein, 1981). Inorganic oxidation of these metals is slow and the precipitation of iron and manganese oxides can be bacterially mediated. Photoreductive dissolution of colloidal iron oxides in aerobic environments (McKnight et al., 1988), reductive dissolution of iron and manganese by anaerobic bacteria (Portier and Palmer, 1989), and desorption of iron and manganese ions held on sediment cation exchange sites (I-Ienrot and Wieder, 1990) have the potential to remobilize metals that have been removed from waste water by other processes. The possibility of iron and manganese remobilization must be considered when evaluating the long-term ability of wetlands to retain metals from waste streams. The objective of this study is to determine the physical, chemical, and biological processes governing the cycling of iron and manganese in a natural freshwater wetland system. This information will guide efforts to design artificial wetlands for the treatment of waste solutions containing iron and manganese and allow more objective evaluation of the possible effects of the use of natural wetlands as a treatment technology for iron and manganese removal.

Genetic types of manganese oxide deposits in Scotland; indicators of paleo-ocean-spreading rate and a Devonian geochemical mobility boundary

There are over 70 occurrences of manganese oxides throughout Scotland; of these, only 13 are sufficiently well developed to be worthy of description. The deposits are categorized on the basis of the formation processes; eight are supergene ground-water or soil deposits, three formed by weathering, and two are hydrothermal in origin. The chemistry of marine sedimentary exhalative deposits can be related to the paleospreading rate of the once-active ridge and, under favorable conditions of stratigraphic preservation, be used to estimate the halfwidth of the ancient ocean. This approach yields estimates of 5 cm yr (super -1) and about 1,000 km for the spreading rate and maximum half-width of the Ordovician Iapetus ocean, respectively: figures which compare favorably with earlier estimates from faunal migration studies.Several of the Scottish manganese outcrops are associated with Old Red Sandstone (Devonian) sediments--a continental fluvial-lacustrine facies in northern Scotland. Diagenetic remobilization, with subsequent oxidation and deposition, of the manganese within the lacustrine sediments led to the formation of a manganese-rich horizon in the uppermost sections of the Old Red Sandstone sedimentary pile. Previously immobile in the pre-Devonian inorganic reaction-dominant regime, manganese mobility increased dramatically with the introduction of large quantities of organic acids following terrestrial colonization by plants. Climate change from arid to tropical with increased vegetation development promoted the formation of thick, organic-rich soils with the concomitant increase in available manganese-chelating ligands. Organomanganese reactions fundamentally changed the pattern of manganese mobility in the postcolonization surficial environment, making the Devonian a stratigraphic geochemical boundary. These changes in weathering processes would also affect the dispersal patterns of other metals which form organo complexes, gold being an obvious example.

Effects of ocean chemistry, sea level, and climate on the formation of primary sedimentary manganese ore deposits

The mineralogy, geochemistry, and in some cases, the mode of origin of many Phanerozoic sedimentary manganese orebodies are fairly well known, but the effects of the important variables represented by changing ocean chemistry, sea level, and climate on ore formation are only recently being considered. The high degree of mobility of manganese, particularly through redox processes, insures that it can change phase during weathering, transport, deposition, and diagenesis.During chemical weathering, manganese is solubilized in acid, reducing conditions and carried in surface and subsurface waters to the coastal zone, where many of the exploitable deposits can form in slightly reducing (carbonate ores) to oxidizing conditions (oxide ores). Rainfall controls ground-water acidity through fostering vegetation growth. Major deposits at Groote Eylandt, Australia, and the extensive deposits of the Paratethys seaway in eastern Europe and the Soviet Union accumulated as a result of large-scale delivery of dissolved Mn to restricted black shale basins during marine transgressions. The deposits show compositional zoning and display evidence of having been deposited in shallow-marine environments following accumulation of a dilute ore solution in the basin interiors. Manganese was precipitated when the environments of the basin became oxidized, apparently during the early stages of marine regressions.During the Phanerozoic the concentrations of dissolved oxygen and carbon in the oceans varied significantly, in response to large changes in the burial rate of organic carbon. When the rate was high, there was a drawdown of atmospheric CO 2 , which led to global reverse-greenhouse cooling. Later, upon oxidation of sea-floor organic matter, CO 2 was released and greenhouse warming eventuated. Manganese is now known to have precipitated rapidly as crusts in the oceans late in the glacial and early in the interglacial stages of the Quaternary, probably as a result of extensive sea-floor oxidation accompanying the release of CO 2 . This same set of processes, operating over geologic time, may have played a significant role, first, in generating large reservoirs of dissolved manganese in intracratonic basins and in the oceans, and second, by providing the metal for the formation of ore deposits when conditions changed.

Translocation of Manganese in Subterranean Clover (Trifolium subterraneum L. Cv. Seaton Park) I. Redistribution During Vegetative Growth

The mobility of manganese from old leaves and cotyledons during vegetative growth has been examined by following manganese content and radioactive manganese redistribution in parts of subterranean clover plants grown into manganese deficiency. In plants transferred from nutrient solutions with 1 �M Mn2+ to solutions without Mn2+, the amount of manganese in the roots decreased markedly. During the same period there was no net loss of manganese from cotyledons and old leaves, although plants developed severe manganese deficiency symptoms in young leaves. Old leaves of plants given an early supply of 54Mn lost no 54Mn when the plants were transferred to non-radioactive solutions without manganese for 14 days. Silicon, which is known to influence the distribution of manganese within leaves of some plants, had no effect on the loss of total manganese or 54Mn from old leaves. Detached green, mature leaves lost 40% of their manganese within 24 h when aerated in water. If leaching by rain removes substantial amounts of manganese from leaves of plants grown in the field, this may account for reports of manganese mobility in plant phloem. The present results establish that manganese is not mobile in the phloem of subterranean clover plants during vegetative growth.

Translocation of Manganese in Subterranean Clover (Trifolium subterraneum L. Cv. Seaton Park). II. Effect of Leaf Senescence and of Restricting Supply of Manganese to Part of a Split Root System

Split root systems were used to examine the hypothesis that manganese is not mobile in the phloem of subterranean clover plants during vegetative growth. The effect of senescence on manganese mobility was also examined by shading mature leaves. Plants given a luxury supply of radioactive manganese to one half of a split root system failed to translocate any more than a trace of manganese to the other half. Shading and subsequent senescence of a large number of leaves did not cause movement of manganese from them. Omitting an external supply of manganese depressed growth of roots but produced no visual abnormalities even though Mn concentrations decreased to 5 �g/g dry matter of root.

Frittage des melanges pulverulents ternaires fer — chrome — manganese. Role exerce par l'atmosphere de traitement

The sintering behaviour of powder mixtures Fe20 CrxMn (0 ⩽ x ⩽ 25 w %) was considered. In the case of the basic mixture Fe20 Cr (heated under hydrogen) chromium diffuses partially into α-iron, then mainly into austenite, once the surface oxyde is reduced; on the other hand under argon, chromium diffusion is more limited, and operates only at high temperature into γ-iron. Whatever the treatment atmosphere, an addition of manganese leads to a noticeable diffusion of this element, first into iron (T < 730°C), then into chromium and iron (T > 730°C). Due to the greater mobility of manganese, disturbing KIRKENDALL effects are observed during sintering, especially in the case of the higher manganese contents. However, homogeneous and dense alloys can be obtained by sintering at high temperature; according to the manganese content, the structure consists of a single-phase α when x < 6.5 wt % Mn, or of two or three phases when x > 7 wt % Mn.

Steady-state diffusion of zinc and manganese at high concentrations in fcc Cu-Zn-Mn ternary alloys

Diffusion phenomena under substitutional steady-state conditions in a Cu-Zn-Mn system were investigated at 800 °C, using vapor-solid couple, in order to evaluate the atomic mobility of zinc and manganese in the α phase region. The experimental diffusion cell consisted essentially of a thin membrane of copper of negligible vapor pressure and a high-vapor-pressure source of zinc alloy chips that was charged on one side of the copper membrane, while the other side was charged with one of the following: Cu-Mn alloy chips, fine manganese powder, or manganese powder mixed with manganese chloride in order to accelerate the movement of manganese atomic vapor. Five series of steady-state diffusions were obtained by this experiment, and the atomic mobilities of zinc and manganese calculation were made along each of the steady-state diffusion path concentration profiles. From these calculated atomic mobilities, a contour map of the isomobility lines of zinc and manganese was formed in the high-alloy-content region of the α phase in Cu-Zn-Mn ternary alloy system.

Cadmium and manganese flux in eelgrass Zostera marina II. Metal uptake by leaf and root-rhizome tissues

Cadmium and manganese radionuclide uptake by Zostera marina L. tissues and translocation between rootrhizomes and leaves was examined. Cadmium concentrations in root-rhizomes increased with incubation time but appeared to reach saturation levels at 24 h of exposure. Translocation of cadmium between root-rhizomes and leaves occurred in both directions. A greater flux of cadmium downward suggested that root-rhizomes were a cadmium sink. Cadmium flux in either direction could be enhanced by a salt gradient. Cadmium appears to move through eelgrass by diffusion or mass flow through vascular tissues and apparent free spaces. Manganese is less mobile but is more readily fixed by leaves. Manganese mobility is not enhanced by salt gradients. Incorporation of cadmium and manganese into root-rhizomes from labelled anoxic sediments was several orders of magnitude less than that from labelled anoxic seawater media.

Manganese Mobility in Egyptian Soils as affected by Inoculation with Manganese Reducing Organisms

AbstractThe capacity of three active Mn(IV)‐reducing isolates to dissolve Mn in sterilized samples of two Egyptian soils and a pure sand enriched with MnO2 were studied. These isolates were identified as Penicillium variable (P. v.), Aspergillus niger (A. n.) and Streptomyces exfoliatus (S. e.).The data indicated that inoculation with the fungi and actinomycete mentioned increased the soil contents of water soluble + exchangeable manganese (Mnws+ex) but decreased the easily reducible form (Mner). The increase in Mn‐mobility depended on soil type, organism used and time of incubation. The maximum level of Mnws+ex appeared after 14 days in the 3 soil samples. The release of Mn (II) ranged from 19.6 to 49.4 ppm in the sand samples, from 34.8 to 53.3 ppm in samples of a clay loam soil and from 9.9 to 19.8 ppm in samples of a calcareous sandy loam soil. The increase in Mnws+ex was at the expense of Mner but not in stochiometric amounts. The organisms tested can be ranked according to their capacity to reduce MnO2 in the following order (for all soils) Streptomyces exfoliatus &gt; Aspergillus niger &gt; Penicillium variable.Statistical analysis of the data revealed significant differences due to inoculation, soil type, incubation time and their interactions.

The application of regional geochemical reconnaissance data in areas of arable cropping

AbstractCopper, magnesium, manganese and zinc have been studied in stream sediments and soils in five representative areas of arable cropping in southern and eastern England. Results have been assessed on the one hand in relation to the geochemistry of bedrock and soil parent materials, and on the other to crop production. Stream sediment data closely reflected the total concentration of copper, magnesium and zinc in soils and at the same time were proportionately related to “available” levels of copper and magnesium in soils. On the basis of reported problems and field trials, concentrations of less than 7 parts/106 Cu and 600 parts/106 Mg in sediments are likely to delineate areas within which a proportion of soils are deficient in these elements, possibly leading to a reduction in yields in sensitive arable crops. Zinc data for sediments and soils were difficult to evaluate in the absence of recognised deficiencies in field crops in Britain. The marked effect of soil Eh/pH on the mobility of manganese in soils and on its availability to plants limits the use of this technique in predicting deficient areas. The possible importance of marginal soil deficiencies of copper leading to reduced yields in cereals is discussed together with the potential value of regional geochemical maps in delineating areas where such problems may be of economic significance.

Relative Mobility of Iron and Manganese in Sedimentary Processes

Alfsen and Christie1 have used thermodynamics to suggest that under some naturally occurring Eh and pH conditions iron would be reduced and mobilized in solution as the Fe2+ ion whereas manganese would remain relatively immobile in its higher oxidation states in solid compounds. This suggestion, although a minor part of their paper, deserves comment because it contradicts the long standing conclusions of Kraus-kopf2 which have been accepted by others3,4.

Relative Mobility of Iron and Manganese in Sedimentary Processes: Reply

IN our letter1 we reported variations in minor and trace element concentrations in different layers of a sedimentary iron ore pisolith. We have demonstrated that spark source mass spectrometry is a convenient technique for trace element analysis of such layers.

Mobility of manganese in diagenesis of deep-sea sediments

A relatively high content of manganese has been found at the top of several deep-sea sediment cores from the Pacific. The sediments underlying these manganese-rich layers show evidence of reducing conditions. The data suggest that manganese dissolves upon burial in reduced sediments, then slowly migrates and accumulates in the oxidized top strata. Ionic or molecular diffusion in the pore solution appears to be the main mechanism by which such migration takes place. The thickness of the manganese-rich layer increases towards the open ocean, both in the eastern as well as the western Pacific; ultimately it reaches such a thickness that it cannot be penetrated by cores obtainable with present equipment. The existence of reduced strata at depth consequently might also occur in deposits from central oceanic areas of the Pacific, where relatively high oxidizing conditions have generally been envisioned to prevail through the entire sedimentary column. Some geochemical implications of the redistribution of manganese and associated elements in deep-sea sediments are briefly discussed.

Genesis and mineralogenetic trend of the manganese ore bodies at Chikla, Sitasaongi and Dongri Buzurg, Bhandara District, Maharashtra, India

Bedded deposits in metasedimentary rocks of almandine-amphibolite facies contain braunite, hollandite, and hausmannite of two generations, plus bixbyite, vredenburgite, jacobsite, manganite, and hematite. The paragenesis of these minerals suggests that they formed by regional metamorphism of manganiferous sediments. Post-metamorphic lower-temperature dioxide ores with colloidal textures form replacement ore bodies that indicate considerable mobility of manganese.

The Mobility of Manganese in the Wheat Plant

Wheat plants were grown in solution culture at two levels of manganese supply until the second leaves were fully expanded. The supply of manganese was then curtailed and symptoms of deficiency appeared in subsequent growth. Although redistribution of manganese at rates dependent upon initial content occurred in both high- and low-manganese plants, first and second leaves always retained sufficient for normal function, and remained healthy. In a second experiment no redistribution from the second leaves was observed under similar conditions of supply and demand. When second leaves were killed and placed in water, up to 80 per cent, of the manganese diffused out, but extraction of similar leaves with 80 per cent, methanol removed only 15—20 per cent, of that present. These results suggest that the lack of mobility shown by the element is not due to precipitation or complex formation within the tissue, although at high levels of manganese supply the solubility of manganese silicate might be exceeded, and some precipitation may occur.

The Mobility of Manganese in the Wheat Plant

The distribution of manganese in wheat plants grown in solution culture has been studied. Manganese supply from the medium was so arranged that early leaves received sufficient for normal function but subsequent growth was severely restricted by deficiency of the element. Under these conditions little or no redistribution within the plant was observed, so that the early leaves retained most or all of their manganese, and remained healthy. When manganese was applied externally to the second leaves of deficient plants a small but significant amount was translocated to the growing points. The effect was slightly enhanced by repeated rewetting of the treated leaves, but the amount moved was still small in relation to that applied and to the requirement of the plants. It appears that manganese is not readily transported by the phloem under these conditions, but this does not wholly account for the ability of some leaves to retain critical levels when a state of deficiency exists at the growing points. Possible mechanisms for this effect are discussed.