Abiotic catalysis natural environments

The rates of Mn(II) oxidation in natural waters, although slow, are typically orders of magnitude faster than the rate of oxidation of Mn(II) in solution (8,12). It has been suggested that the enhanced rate of Mn(II) oxidation in natural waters is due either to bacterial oxidation (13-16) or to the "catalytic" effects of surfaces such as metal oxides (8, 17-19). The existing evidence suggests that in certain environments bacterial mediation of the reaction is important (13-15). But in many cases the relative importance of bacterial and abiotic "catalysis" in natural waters has not been clearly defined. 

Little is known on the catalysis of the Maillard reaction and especially the integrated polyphenol-Maillard reaction by natural soils and sediments. Further work is warranted on this subject matter to advance our understanding of the role of abiotic catalysis in the formation of humic substances and related C turnover and N transformations in the environment. 

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