999 resultados para Michigan.
Resumo:
Manganese nodules containing up to 22 percent manganese oxide were found in Green Bay and the western and northern parts of Lake Michigan. The chemical composition of these nodules resembles that of shallow-water lacustrine and marine nodules. The manganese content of interstitial water is in some places enriched as much as 4000 times over that of lake water.
Resumo:
The differential solubility of ferromanganese oxides can lead to stratigraphic separation of iron and manganese. Results of chemical analysis of a sequence of ferromanganese nodules overlying iron-rich crusts in northern Green Bay show that selec¬tive ion transport is important in concentrating manganese and associated trace elements near the oxygenated water-sediment interface. Manganese carbonate, which cements ferromanganese nodules, occurs in dark-gray silty sands that are located adjacent to the organic-rich muds of southern Green Bay. These muds contain an average of approximately 3.5 ppm (6x10-5M) interstitial Mn with 2.8 meq/l carbonate alkalinity. Thermodynamic calculation shows that interstitial water approaches equilibrium with MnCO3 in the upper 10 cm of sediment. This carbonate has a composition (Mn73Ca22Fe5)CO3 and has been identified as rhodochrosite.
Resumo:
1910
Resumo:
25
Resumo:
1876
Resumo:
45
Resumo:
1915
Resumo:
41
Resumo:
1889
Resumo:
1880
