Manganese cycling

Aller, R.C. (1990) Bioturbation and manganese cycling in hemipelagic sediments. Phil. Trans. Royal Soc. London 331, 51-68. 

Slomp, C.P., Malschaert, J.F.P., Lohse, L., and van Raaphorst, W. (1997) Iron and manganese cycling in different sedimentary environments on the North Sea continental margin. Cont. Shelf Res. 17, 1083-1117. 

Pimenov NG, Neretin LN (2006) Composition and activities of microbial communities involved in carbon, sulfur, nitrogen and manganese cycling in the oxic/anoxic interface of the Black Sea. In Neretin LN (ed) Past and present water column anoxia. NATO Sciences Series. Springer, Dordrecht, p 501... 

Example 3.2 In oxic waters, Mn2+ is normally oxidized to MnCfys)- Under certain circumstances, Mn3+ is also produced. In order to better understand manganese cycling at the oxic/anoxic interface, thermodynamics offers its predictive power. From this point of view, and assuming standard conditions and concentrations,... 

Fig. 5.1. Biogeochemical manganese cycle in marine and terrestrial systems. Arrows indicate the mobilization of manganese as Mn(II) by microbial activity, leading to micro-bially-induced deposition of manganese as Mn(IV) under suitable conditions.

Figure 6.5 Electron transfer reactions for sediments (Ruddy, 1993). CHjO.N.P (organic matter) is transformed by bacterial decomposition reactions to bicarbonate in the pore-waters. This is the primary source of electrons (and therefore energy) for the remainder of the sediment redox chemistry. Most of the primary flux of electrons may pass through the sulphur, iron and manganese cycles, but will eventually react with oxygen. Only a small part of the total electron flux will ultimately be buried as reduced minerals.

In the case of Mn, there is evidence for a role of ectoenzymes in both oxidation and reduction reactions (Fig. 6). Manganese cycling in the photic zone of natural waters involves a redox transition between dissolved Mn(II) and particulate Mn(IV). In freshwater, Mn(II) oxidation by algal photosynthetic activity has been reported (Richardson et al., 1988) and may indirectly involve the enzyme carbonic anhydrase, which catalyzes the conversion of bicarbonate to carbon dioxide extracellularly. For bicarbonate utilizing species of algae, a more rapid... 

I ihiiit ft. Manganese cycling ami (lie role of cell surface enzymes. ( onsult the text for an explanation I (Ins eyelc. 

Nealson, K. H. (1983), The Microbial Iron Cycle, and The Microbial Manganese Cycle, in W. E. Krumbein, Ed., Microbial Geochemistry, Blackwell, Oxford, pp. 159-221. 

Egeberg PK, Schaanning M, Naes K, et al. 1988. Modelling the manganese cycling in two stratified Ijords. Marine Chemistry 23 383-391. 

Fig. 7.21 Example of manganese cycling across the sediment/bottom water interface and within the sediment (modified after Sundby and Silverberg (1985). The applied depth-dependent flux model is described in the text. Depo-sitional, burial, and molecular diffusive fluxes as well as the reduction rate within the zone of dissolution were calculated independently.

Johnson, D., Chiswell, B. and O Halloran, K. (1995) Micro-organisms and manganese cycling in a seasonally stratified freshwater dam. Water Research 29, 2 739-2 745. 

FIGURE 10.2 Schematic showing manganese cycling in wetlands and aquatic systems. 

Johnson, C. A., M. Ulrich, L. Sigg, D. M. Imboden, 1991. A mathematical model ofthe manganese cycle in a seasonally anoxic lake. Limnol. Oceanogr. 36 1415-1426. 

FIG. 8.2 Nitrogen cycles and manganese cycles release less energy than oxygen reactions. The energy in a transition from the electron source on the left to the electron sink on the right is depicted as a version of redox potential called pE. 

---