8
F. J. Millero
have the same salinity (even though the composition may differ). Since salinity is normally used to determine a physical property like density, this was thought to be the
best method for determining the effect of changes in ionic composition. This is not
always the case since non-electrolytes like Si02 are not detected by conductivity. The
final equation is:
S = ao + aj Rjl2 + a2Rr + a3R~!2 + a4Ri + asRi/2 + ~S
(1.8)
where
~S = [(t - 15) I (1+ k(t - 15))]b o + bj Rjl2 + b 2 R r + b 3 Ri'2 + b4Ri + b s Ri /2
(1.9)
and Rr = C (S, t, 0) I C (35, t, 0) at atmospheric pressure (p = 0). The coefficients are
given in Table 1.2. The scale is valid from S = 2 to 42 and t = 0 to 40°C. Hill et al. (1986)
have formulated equations that can be used in more dilute solutions. The practical
salinity has no units.
1.1.3
Causes of Major Components Not Being Conservative
Although the major components of sea water are relatively constant, a number of factors can cause the waters to be non-conservative. They include processes that occur in
(1) estuaries, anoxic basins, sediments, hydrothermal vents, and evaporated basins, and
(2) by precipitation, dissolution, evaporation, freezing, and oxidation. Some examples
will be briefly discussed.
The finding of hydrothermal vents has led to the discovery that a number of elements can be added (Ca, Cu, Zn, Mn, Si) and taken out (Mg, S04) of ocean waters. The
loss of Mg for hydrothermal vent waters is shown in vent fluids of high Si02 in Fig. 1.5.
The waters coming out of the vent at high temperatures are devoid of Mg. This is related to the formation of Mg silicates when the sea water reacts with molten basalt. As
shown in Fig. 1.6, this deficiency of Mg changes the amount of Mg in deep Pacific waters.
Table 1.2. Coefficients needed
to calculate the practical salinParameter
Value
Parameter
Value
ity of sea water from conductivity measurements
a o
0.0080
b o
0.0005
a 1
-0.1692
b 1
-0.0056
a 2
25.3851
b 2
-0.0066
a 3
14.0941
b 3
-0.0375
a 4
-7.0261
b 4
0.0636
as
2.7081
b s
-0.0144
La;=
35.000
Lbj =
0.0000
k=
0.0162
F. J. Millero
have the same salinity (even though the composition may differ). Since salinity is normally used to determine a physical property like density, this was thought to be the
best method for determining the effect of changes in ionic composition. This is not
always the case since non-electrolytes like Si02 are not detected by conductivity. The
final equation is:
S = ao + aj Rjl2 + a2Rr + a3R~!2 + a4Ri + asRi/2 + ~S
(1.8)
where
~S = [(t - 15) I (1+ k(t - 15))]b o + bj Rjl2 + b 2 R r + b 3 Ri'2 + b4Ri + b s Ri /2
(1.9)
and Rr = C (S, t, 0) I C (35, t, 0) at atmospheric pressure (p = 0). The coefficients are
given in Table 1.2. The scale is valid from S = 2 to 42 and t = 0 to 40°C. Hill et al. (1986)
have formulated equations that can be used in more dilute solutions. The practical
salinity has no units.
1.1.3
Causes of Major Components Not Being Conservative
Although the major components of sea water are relatively constant, a number of factors can cause the waters to be non-conservative. They include processes that occur in
(1) estuaries, anoxic basins, sediments, hydrothermal vents, and evaporated basins, and
(2) by precipitation, dissolution, evaporation, freezing, and oxidation. Some examples
will be briefly discussed.
The finding of hydrothermal vents has led to the discovery that a number of elements can be added (Ca, Cu, Zn, Mn, Si) and taken out (Mg, S04) of ocean waters. The
loss of Mg for hydrothermal vent waters is shown in vent fluids of high Si02 in Fig. 1.5.
The waters coming out of the vent at high temperatures are devoid of Mg. This is related to the formation of Mg silicates when the sea water reacts with molten basalt. As
shown in Fig. 1.6, this deficiency of Mg changes the amount of Mg in deep Pacific waters.
Table 1.2. Coefficients needed
to calculate the practical salinParameter
Value
Parameter
Value
ity of sea water from conductivity measurements
a o
0.0080
b o
0.0005
a 1
-0.1692
b 1
-0.0056
a 2
25.3851
b 2
-0.0066
a 3
14.0941
b 3
-0.0375
a 4
-7.0261
b 4
0.0636
as
2.7081
b s
-0.0144
La;=
35.000
Lbj =
0.0000
k=
0.0162