SOLUTION 1 temp 25 pH 5.1 pe 4 redox pe units mg/l density 1 Ca 0 Fe(2) 33.2 Fe(3) 186.8 Mn(2) 67.6 S(6) 200 charge -water 1 # kgEQUILIBRIUM_PHASES 1 CO2(g) -3.5 0 O2(g) -6.7 0SOLUTION_MASTER_SPECIES C(0) CH2O 0 CH2O 12SOLUTION_SPECIESCH2O = CH2O log_k 0CH2O + 6OH- = CO3-2 + 4e- + 4H2O log_k 103PHASESOrganic_C SO4-2 + 2CH2O = 2CO3-2 + 3H+ + HS- log_k 100KINETICS 1Organic_C -formula Organic_C -m 1 -m0 1 -tol 1e-08-steps 100 in 100 steps # seconds-step_divide 1-runge_kutta 3-bad_step_max 500RATES Organic_C-start 1 REM Additive Monod kinetics for SOC (sediment organic carbon) 2 REM Electron acceptors: O2, NO3, and SO4 10 if (M <= 0) THEN GOTO 200 20 mO2 = MOL("O2") 30 mNO3 = TOT("N(5)") 40 mSO4 = TOT("S(6)") 50 k_O2 = 1.57e-9 60 k_NO3 = 1.67e-11 70 k_SO4 = 1.e-13 80 rate = k_O2 * mO2/(2.94e-4 + mO2) 90 rate = rate + k_NO3 * mNO3/(1.55e-4 + mNO3)100 rate = rate + k_SO4 * mSO4/(1.e-4 + mSO4)110 moles = rate * M * (M/M0) * TIME200 SAVE moles-endUSE equilibrium_phases 1USE kinetics 1USE solution 1USER_GRAPH 1 -headings C SO4 S(-2) -axis_titles "Carbon added, mol/L" "S(6) Concentration, mol/L" "S(2) Concentration, mol/L" -initial_solutions true -connect_simulations true -plot_concentration_vs x -start10 graph_x TOTAL_TIME20 graph_y tot("S(6)")30 GRAPH_SY tot("S(-2)") -end -active trueUSER_GRAPH 2 -headings C Fe(2) Fe(3) -axis_titles "Carbon added, mol/L" "Fe(2) Concentration, mol/L" "Fe(3) Concentration, mol/L" -initial_solutions true -connect_simulations true -plot_concentration_vs x -start10 graph_x TOTAL_TIME20 graph_y tot("Fe(2)")30 GRAPH_SY tot("Fe(3)") -end -active trueUSER_GRAPH 3 -headings C Mn -axis_titles "Carbon added, mol/L" "Concentration, mol/L" "" -initial_solutions true -connect_simulations true -plot_concentration_vs x -start10 graph_x TOTAL_TIME20 graph_y tot("Mn(2)") -end -active trueUSER_GRAPH 4 -headings C Goethite Pyrolusite Mackinawite Manganite -axis_titles "Carbon added, mol/L" "Concentration, mol/L" "" -initial_solutions true -connect_simulations true -plot_concentration_vs x -start10 graph_x TOTAL_TIME20 graph_y EQUI_DELTA("Goethite"),EQUI_DELTA("Pyrolusite"),EQUI_DELTA("Mackinawite"), EQUI_DELTA("Manganite") -end -active trueEND