Redox-sensitive trace elements, oxidation

The oxidation state of redox-sensitive trace elements such as As(III)/ As(V) and Cr(III)/Cr(VI) is thus affected by the redox conditions, as indicated by the occurrence of major reduced species. Kinetic control of the redox reactions plays an important role. As(III) appears in the anoxic hypolimnion in agreement with the thermodynamic redox sequence together with Fe(II) and sulfide, although the reduction of As(V) is incomplete under these conditions. Whereas the reduced As(III) species can clearly be observed in the... 

Yang W. and Holland H. D. (2002) The redox sensitive trace elements Mo, U, and Re in Precambrian carbonaceous shales indicators of the Great Oxidation Event (abstr.). Geol. Soc. Am. Ann. Mtng. 34, 382. 

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