# Find 13C when gypsum is added to calcite/dolomite equilibrated solution RATES Gypsum # Add 1 mmol gypsum in 1 s -start 10 save 1e-3 * time -end Calcite # rate is for 13C integration only... -start 10 moles = 1e-1 * (1 - sr("Calcite")) * time 20 put(moles, 1) # ...for C13 kinetics 30 save moles -end Dolomite # rate is only for 13C integration... -start 10 moles = 1e-1 * (1 - sr("Dolomite")) * time 20 put(moles, 2) # ...for C13 kinetics 30 save moles -end Carbon13 # Distribute 13C among solute species 1= CO2aq, 2= HCO3-, # 3=CO3-2, and in calcite. -start # Define alpha's from Clark and Fritz, 1997, p. 121 ... 4 T = TK 10 aa_1_2 = exp(24.29e-3 - 9.925 / T) 20 aa_3_2 = exp(20.7e-3 - 9.552 / T + 870 / T^2) 30 aa_cc_2 = exp(26.561e-3 - 17.2183 / T + 2988.0 / T^2) # Find H12CO3- and H13CO3-... 50 aH = act("H+") 60 K1 = aH * act("HCO3-") / act("CO2") / act("H2O") 70 K2 = aH * act("CO3-2") / act("HCO3-") 80 m12C = (tot("C(4)")) / (aH/K1 + 1 + K2/aH) 90 m13C = m / (aa_1_2 * aH/K1 + 1 + aa_3_2 * K2/aH) # and the ratio 13C/12C in HCO3-... 100 R2 = m13C / m12C # Fractionate 13C into calcite... 110 d13C_cc = aa_cc_2 * -get(1) * R2 # Add 13C from dolomite with d13C = -2 permil ... 120 d13C_dol = get(2) * 2 * 0.0112145 # Integrate... 130 save d13C_cc - d13C_dol -end KINETICS 1 Gypsum; Calcite; Dolomite Carbon13; -formula C 0; -m0 0.0366E-3# d13C = -13 for TIC = 3.3e-3 -step 1 # only 1 step in 1 second SOLUTION 1 -temp 15; pH 7 charge; S(6) 0.1; Ca 1 Calcite; Mg 1 Dolomite; C(4) 3.3 USER_PRINT -start 10 Rst = 0.011237 20 print 'd13C of solution : ', (kin("Carbon13") / tot("C(4)") / Rst - 1) * 1e3 -end END