# Kinetic dissolution of quartz
#
RATES
Quartz
# d qu / dt = (A0 / V) * (m / m0)^0.67 * k * (1 - SI_qu)
# Specific rate k from Rimstidt and Barnes, 1980, GCA 44, 1683
# k = 10^-13.7 mol/m2/s (25 C)
# A0, initial surface of quartz (m2) recalc's to mol/s
# V, solution volume in contact with A0
-start
1 A0 = parm(1)
2 V = parm(2)
10 rate = (A0 / V) * (m/m0)^0.67 * 10^-13.7 * (1 - SR("Quartz"))
20 save rate * time
-end
KINETICS
Quartz
-m0 158.8 # moles of quartz
-parms 23.13 0.16
-step 1.5768e8 in 15 # seconds in 10 steps
INCREMENTAL_REACTIONS true

SOLUTION 1
USER_GRAPH
-headings time Si
-chart_title "Quartz dissolution"
-axis_titles Years "mmol / L"
-headings time Si
-axis_scale y_axis 0 0.12 0.02
-axis_scale x_axis 0 5
-initial false
-start
10 graph_x total_time/3.1536e7 # time in years on x-axis
20 graph_y tot("Si") * 1e3 # parameter on y-axis
-end
END