Manganese undergoes dynamic redox cycling between reduced Mn(II) and manganese oxides. These transfers dominate the biogeochemical behavior of manganese in natural waters and sediments. Although the manganese redox cycle is likely to have a major impact on the chemistry of other elements, particularly carbon, such effects have not been widely studied. Thus manganese serves as a redox catalysts for the transfer of electrons between organic matter and molecular oxygen and plays an important role in the overall redox chemistry of sediments. By studying the microbial and abiotic reduction of manganese oxides in sediments, the work fills an important gap in our knowledge of elemental redox cycles in sediments, particularly with respect to understanding the role of manganese in the oxidation of organic carbon. Biogeochemical cycling of manganese in this large freshwater system will provide an understanding of how this element relates to the carbon cycle. Previous notions about how manganese is reduced in anoxic environments have recently been changed by studies in Lake Oneida and the Black Sea. These distinct regions have sulfide in common, however the dominant cause of manganese reduction was due to organisms above the sulfide interface. This rather surprising result adds impact to these studies in Green Bay indicates that the results may be extrapolated to many other freshwater and marine environments. It is important to oceanographers as well as meteorologists to know how carbon is exchanged and cycled throughout the ocean.
