# DO input concentration

Title: DO input concentration

David,

I'm a bit confused about the input concentration for DO in mg/l.
If I have 4mgO2/L, should I than enter 4mg/L for O(0)?
I tried to find out, and this gave me the correct result of 1.25e-5molO2/L and 2.5e-5molO(0)/L
is this correct?

This is maybe a stupid question, but I got confused why not entering conc "as O2", but then I get 6.284e-005molO2/l as a result, which is 2mgO2/l.

best regards,
bruno

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Reading input data for simulation 1.
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DATABASE C:\Program Files\Phreeqc\Phreeqc.dat
SOLUTION 1
temp      25
pH        7.92
pe        4
redox     pe
units     mg/l
density   1
O(0)      4.02
Na        19.8
K         4.9
Ca        73.3
Mg        33.5
Cl        78
S(6)      95 as SO4
N(5)      55 as NO3
Alkalinity 140
water    1 # kg
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Beginning of initial solution calculations.
-------------------------------------------

Initial solution 1.

-----------------------------Solution composition------------------------------

Elements           Molality       Moles

Alkalinity       2.799e-003  2.799e-003
Ca               1.830e-003  1.830e-003
Cl               2.201e-003  2.201e-003
K                1.254e-004  1.254e-004
Mg               1.379e-003  1.379e-003
N(5)             8.874e-004  8.874e-004
Na               8.617e-004  8.617e-004
O(0)             2.514e-004  2.514e-004
S(6)             9.894e-004  9.894e-004

----------------------------Description of solution----------------------------

pH  =   7.920
pe  =   4.000
Activity of water  =   1.000
Ionic strength  =  1.079e-002
Mass of water (kg)  =  1.000e+000
Total carbon (mol/kg)  =  2.823e-003
Total CO2 (mol/kg)  =  2.823e-003
Temperature (deg C)  =  25.000
Electrical balance (eq)  = -4.625e-004
Percent error, 100*(Cat-|An|)/(Cat+|An|)  =  -3.26
Iterations  =   7
Total H  = 1.110152e+002
Total O  = 5.552149e+001

---------------------------------Redox couples---------------------------------

Redox couple             pe  Eh (volts)

O(-2)/O(0)          12.6251      0.7469

----------------------------Distribution of species----------------------------

Log       Log         Log
Species            Molality    Activity  Molality  Activity     Gamma

OH-              9.282e-007  8.325e-007    -6.032    -6.080    -0.047
H+               1.320e-008  1.202e-008    -7.880    -7.920    -0.040
H2O              5.551e+001  9.998e-001     1.744    -0.000     0.000
C(4)            2.823e-003
HCO3-            2.656e-003  2.396e-003    -2.576    -2.621    -0.045
CO2              6.462e-005  6.478e-005    -4.190    -4.189     0.001
CaHCO3+          3.731e-005  3.367e-005    -4.428    -4.473    -0.045
MgHCO3+          2.590e-005  2.329e-005    -4.587    -4.633    -0.046
CaCO3            1.725e-005  1.729e-005    -4.763    -4.762     0.001
CO3-2            1.410e-005  9.346e-006    -4.851    -5.029    -0.179
MgCO3            7.389e-006  7.407e-006    -5.131    -5.130     0.001
NaHCO3           1.038e-006  1.041e-006    -5.984    -5.983     0.001
NaCO3-           1.496e-007  1.344e-007    -6.825    -6.871    -0.046
Ca              1.830e-003
Ca+2             1.663e-003  1.101e-003    -2.779    -2.958    -0.179
CaSO4            1.120e-004  1.123e-004    -3.951    -3.950     0.001
CaHCO3+          3.731e-005  3.367e-005    -4.428    -4.473    -0.045
CaCO3            1.725e-005  1.729e-005    -4.763    -4.762     0.001
CaOH+            1.691e-008  1.520e-008    -7.772    -7.818    -0.046
Cl              2.201e-003
Cl-              2.201e-003  1.975e-003    -2.657    -2.704    -0.047
H(0)            2.042e-027
H2               1.021e-027  1.023e-027   -26.991   -26.990     0.001
K               1.254e-004
K+               1.249e-004  1.121e-004    -3.903    -3.950    -0.047
KSO4-            4.510e-007  4.054e-007    -6.346    -6.392    -0.046
KOH              3.224e-011  3.232e-011   -10.492   -10.491     0.001
Mg              1.379e-003
Mg+2             1.246e-003  8.306e-004    -2.905    -3.081    -0.176
MgSO4            9.923e-005  9.948e-005    -4.003    -4.002     0.001
MgHCO3+          2.590e-005  2.329e-005    -4.587    -4.633    -0.046
MgCO3            7.389e-006  7.407e-006    -5.131    -5.130     0.001
MgOH+            2.790e-007  2.508e-007    -6.554    -6.601    -0.046
N(5)            8.874e-004
NO3-             8.874e-004  7.946e-004    -3.052    -3.100    -0.048
Na              8.617e-004
Na+              8.583e-004  7.725e-004    -3.066    -3.112    -0.046
NaSO4-           2.201e-006  1.978e-006    -5.657    -5.704    -0.046
NaHCO3           1.038e-006  1.041e-006    -5.984    -5.983     0.001
NaCO3-           1.496e-007  1.344e-007    -6.825    -6.871    -0.046
NaOH             4.234e-010  4.244e-010    -9.373    -9.372     0.001
O(0)            2.514e-004
O2               1.257e-004  1.260e-004    -3.901    -3.900     0.001
S(6)            9.894e-004
SO4-2            7.755e-004  5.109e-004    -3.110    -3.292    -0.181
CaSO4            1.120e-004  1.123e-004    -3.951    -3.950     0.001
MgSO4            9.923e-005  9.948e-005    -4.003    -4.002     0.001
NaSO4-           2.201e-006  1.978e-006    -5.657    -5.704    -0.046
KSO4-            4.510e-007  4.054e-007    -6.346    -6.392    -0.046
HSO4-            6.644e-010  5.972e-010    -9.178    -9.224    -0.046

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