Manganese complexes mobilization

Little is known concerning the chemistry of nickel in the atmosphere. The probable species present in the atmosphere include soil minerals, nickel oxide, and nickel sulfate (Schmidt and Andren 1980). In aerobic waters at environmental pHs, the predominant form of nickel is the hexahydrate Ni(H20)g ion (Richter and Theis 1980). Complexes with naturally occurring anions, such as OH, SO/, and Cf, are formed to a small degree. Complexes with hydroxyl radicals are more stable than those with sulfate, which in turn are more stable than those with chloride. Ni(OH)2° becomes the dominant species above pH 9.5. In anaerobic systems, nickel sulfide forms if sulfur is present, and this limits the solubility of nickel. In soil, the most important sinks for nickel, other than soil minerals, are amorphous oxides of iron and manganese. The mobility of nickel in soil is site specific pH is the primary factor affecting leachability. Mobility increases at low pH. At one well-studied site, the sulfate concentration and the... 

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... 

The ESR spectrum of Mn in sodium azide [28] shows a remarkable similarity to that of Mn in sodium chloride. In both cases the divalent manganese ion is located substitutionally at a monovalent sodium ion site, and the extra positive charge is compensated by a cation vacancy. The same mobility and coagulation effects are seen for both materials, and multiple sets of Mn —cation vacancy complexes are also observed. Vacancy hopping, which produces lifetime broadening of the resonance lines, is observed in NaNa (as well as in potassium and rubidium azides). As mentioned earlier. Miller and King [13] used the ESR spectrum of Mn " to observe the phase transition at 19°C. 

The ability of organisms to create conditions to form organic Fe or Mn complexes and increase the mobility of iron and manganese... 

Several other complexing reagents are effective masking agents when added to the sample but not to the mobile phase. Nitrilotriacetic acid (NTA) masks a 10- to 100-fold excess of aluminum] 111), copper]II), nickel]II) or iron]III) when magne-sium]II), calcium and manganese] ) are to be determined by IC. Analysis of rare-... 

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