Below about pH 3.5, ferrous iron oxides in streams according to the overall reaction Fe+ + 1/4 0 + H+. > Fe+ + 1/2 HO. The rate law for the inorganic oxidation of ferrous iron under these conditions is given by :d[Fe(11)/dt = -K (Fe (1) PO2 at 20C where k, = 10-3.2/ bar day. Nordstrom (1985) measured the oxidation rate of ferrous iron in an acid mine drainage stream in which the initial Fe+ concentration was 300 mg/L. The stream had a practically constant pH of about 2.5. The ferrous iron concentration dropped to about 5 mg/L after the stream had flowed for about 24 hours at about 0.2 m/s. Nordstrom concluded that the oxidation process was independent of the ferrous iron concentration, but was instead proportional to the concentration of the iron-oxidizing bacteria, T. ferrooxidans, in the stream. (a) Calculate the reduction in ferrous iron concentration expected in the stream during this same 24 hour period due only to inorganic oxidation as expressed in the above rate law and compare it to the reduction in Fe2+ reported by Nordstrom. (b) Using Nordstrom's empirical data for the rate of bacterial oxidation of Fe (II) in the stream, calculate the + apparent rate constant, k, of the pseudo first-order reaction assuming Poz = 0.21 bar, and compare it to the apparent rate constant for the inorganic oxidation reaction.