231
Dissolved Gases Other than CO 2
the integrated van Hoff equation. The final form used by Weiss (1971) is
ln C = A 1 + A 2 (100/T) + A 3 ln(T/100) + S[B 1 + B 2 (T/100) + B 3 (T/100) 2 ]
(6.18)
The coefficients A i are related to the solubility of the gas in water at various temperatures,
while the coefficients B i are related to the solubility of the gas in seawater. The effect of
temperature on the salting coefficient B 2 is not of the proper van Hoff form (Equation
6.17). The B 2 and B 3 terms should be functions of 1/T and ln T, respectively. The values of
A i and B i for various gases when [i] is in units of micromoles per kilogram are given in
Table 6.3. Values of [i] expressed in these units for S = 35 seawater are given in Table 6.4. It
is important to point out that the use of Equation 6.18 smoothes out the variability of gas
Table 6.3
Solubility of Gases in Seawater with the Constants
for Equation 6.18 in Moles per Kilogram Relative
to Air at 1 atm at 100% Relative Humidity
Gas
A 1
A 2
A 3
A 4
N 2
–173.2221
254.6078
146.3611
–22.0933
O 2
–173.9894
255.5907
146.4813
–22.2040
Ar
–174.3732
251.8139
145.2337
–22.2046
Ne
–166.8040
255.1946
140.8863
–22.6290
He
–163.4207
216.3442
139.2032
–22.6202
B 1
B 2
B 3
N 2
–0.054052
0.027266
–0.0038430
O 2
–0.037362
0.016504
–0.0020564
Ar
–0.038729
0.017171
–0.0021281
Ne
–0.127113
0.079277
–0.0129095
He
–0.44781
0.023541
–0.0034266
Source: Data from Kester, D.R., Dissolved gases other
than CO 2 , in Chemical Oceanography, Vol. 1, 2nd
ed., J.P. Riley and G. Skirrow, Eds., Academic
Press, New York, 498–556, 1975.
Table 6.4
Solubility of N 2 , O 2 , Ar, Ne, and He in Seawater
(S = 35) Equilibrated with the Atmosphere
(P = 1 atm) at 100% Humidity
μmol kg –1
nmol kg –1
N 2
O 2
Ar
Ne
He
Kr
Xe
0°C
616.4 349.5 16.98 7.88 1.77 4.1
0.66
5
549.6 308.1 15.01 7.55 1.73 3.6
0.56
10
495.6 274.8 13.42 7.26 1.70 3.1
0.46
15
451.3 247.7 12.11
7.00 1.68 2.7
0.39
20
414.4 225.2 11.03
6.77 1.66 2.4
0.33
25
383.4 206.3 10.11
6.56 1.65 2.2
0.29
30
356.8 190.3
9.33 6.36 1.64 2.0
0.25
Dissolved Gases Other than CO 2
the integrated van Hoff equation. The final form used by Weiss (1971) is
ln C = A 1 + A 2 (100/T) + A 3 ln(T/100) + S[B 1 + B 2 (T/100) + B 3 (T/100) 2 ]
(6.18)
The coefficients A i are related to the solubility of the gas in water at various temperatures,
while the coefficients B i are related to the solubility of the gas in seawater. The effect of
temperature on the salting coefficient B 2 is not of the proper van Hoff form (Equation
6.17). The B 2 and B 3 terms should be functions of 1/T and ln T, respectively. The values of
A i and B i for various gases when [i] is in units of micromoles per kilogram are given in
Table 6.3. Values of [i] expressed in these units for S = 35 seawater are given in Table 6.4. It
is important to point out that the use of Equation 6.18 smoothes out the variability of gas
Table 6.3
Solubility of Gases in Seawater with the Constants
for Equation 6.18 in Moles per Kilogram Relative
to Air at 1 atm at 100% Relative Humidity
Gas
A 1
A 2
A 3
A 4
N 2
–173.2221
254.6078
146.3611
–22.0933
O 2
–173.9894
255.5907
146.4813
–22.2040
Ar
–174.3732
251.8139
145.2337
–22.2046
Ne
–166.8040
255.1946
140.8863
–22.6290
He
–163.4207
216.3442
139.2032
–22.6202
B 1
B 2
B 3
N 2
–0.054052
0.027266
–0.0038430
O 2
–0.037362
0.016504
–0.0020564
Ar
–0.038729
0.017171
–0.0021281
Ne
–0.127113
0.079277
–0.0129095
He
–0.44781
0.023541
–0.0034266
Source: Data from Kester, D.R., Dissolved gases other
than CO 2 , in Chemical Oceanography, Vol. 1, 2nd
ed., J.P. Riley and G. Skirrow, Eds., Academic
Press, New York, 498–556, 1975.
Table 6.4
Solubility of N 2 , O 2 , Ar, Ne, and He in Seawater
(S = 35) Equilibrated with the Atmosphere
(P = 1 atm) at 100% Humidity
μmol kg –1
nmol kg –1
N 2
O 2
Ar
Ne
He
Kr
Xe
0°C
616.4 349.5 16.98 7.88 1.77 4.1
0.66
5
549.6 308.1 15.01 7.55 1.73 3.6
0.56
10
495.6 274.8 13.42 7.26 1.70 3.1
0.46
15
451.3 247.7 12.11
7.00 1.68 2.7
0.39
20
414.4 225.2 11.03
6.77 1.66 2.4
0.33
25
383.4 206.3 10.11
6.56 1.65 2.2
0.29
30
356.8 190.3
9.33 6.36 1.64 2.0
0.25