3. In suboxic soils (i.e., in the absence of O2 ), dissolution is expected for Fe-containing soil particles, which include magnetite (Fe3O4(s)),Fe(OH)3 amorphous, maghemite (Fe2O3(s) ), lepidocrocite (FeOOH(s)), goethite (FeOOH(s)), pyrite (FeS2), and siderite (FeCO3) to generate Fe2+. a. Given (Fe2+)=105M,H2S=105M and pCO2=0.12atm, construct a pEpH diagram with the relationships for the different Fe-containing particles (9 pts). Discuss what the predominant species will be at oxic (pE+12), sub-oxic (+12pE +2), and anoxic (pE 7) sub-oxic soils, the important aqueous species of selenium (Se) are SeO42 and SeO32. The relevant reduction half-reaction: 21SeO42+H++e=21SeO32+21H2O(l) Determine whether SeO32 can be oxidized to SeO42 (the more toxic Se species) through reduction dissolution of the following Fe-Oxide particles: goethite, pyrite, and siderite. Consider (Fe2+)=105M,pH=7.8, and the poised pE for suboxic soils ( 9 pts)