118
Chemical Oceanography, 4th Edition
Sillén (1967) suggested some imaginary experiments to represent the real ocean system.
He visualized the formation of the oceans as the result of mixing water with a number of
minerals. This mixing, performed perhaps by a well- known bartender, took place over a
period of time to ensure equilibrium. The first model he considered is given in Figure 3.33.
The ion exchange reaction
1.5 Al 2 Si 2 O 5 (OH) 4 (s) + K + → KAl 3 Si 3 O 10 (OH) 2 (s) + 1.5 H 2 O + H +
(3.9)
Kaolinite
K- mica
can control the ratio of H + and pH of the oceans.
Applying equilibrium conditions for this reaction (at constant Cl – and temperature) gives
K = [H + ]/[K + ]
(3.10)
[K + ] + [H + ] = [Cl – ] + Kw/[H + ]
(3.11)
Table 3.8
Metals in Atlantic and Pacific
Deep Waters (nM)
Metal
Atlantic
Pacific
P/ A
Cd
0.29
0.94
3.2
Zn
1.5
8.2
5.5
Ni
5.7
10.4
1.8
Cu
1.7
2.7
1.6
Mn
0.6
—
—
Table 3.10
Metals in Central Gyres
Metal
Atlantic
Pacific
Mn
2.4 nM
1.0 nM
Cu
1.2 nM
0.5 nM
Ni
2.1 nM
2.4 nM
Zn
0.06 nM
0.06 nM
Cd
2 pM
2 pM
Table 3.9
Metals on Shelf versus Open
Sea Surface Waters
Metal
Shelf
Open
Mn
21 nM
2.4 nM
Ni
5.9 nM
2.3 nM
Cu
4.0 nM
1.2 nM
Zn
2.4 nM
0.06 nM
Cd
200 pM
2 pM