Manganese deposits, freshwater

Since most major manganese deposits are of sedimentary origin, it is relevant to consider aspects of microbial transformations of manganese in freshwater and marine systems, including the conditions necessary for microbial involvement in the formation of extensive sedimentary manganese deposits. 

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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