ABSTRACT
The list of elements that can play a controlling role in determining the redox conditions in natural waters is short, and is usually oxygen, nitrogen, iron, sulfur, carbon, and hydrogen. Besides the ClONFeSCH group, other redox-active elements can also be present in natural systems, but usually they are very minor components so that their chemistries tend to “go along for the ride” as established by the dominant redox elements. This chapter considers the pe–pH predominance diagrams of the remaining elements of the ClONFeSCH group, namely nitrogen, iron, sulfur, and carbon, following the order in ClONFeSCH. Solution-phase activity coefficients are assumed to be unity. Nitrogen is in the VA column of the periodic table, so atomic nitrogen has 5 valence electrons. Carbon is in the IVA column of the periodic table, so atomic carbon has 4 valence electrons. Removing 4 electrons takes carbon to the relatively stable state of an empty outer shell, C(VI).
