122
Chemical Oceanography, 4th Edition
Mg was found to be a problem, as well as SiO 2 . More recent results on hydrothermal vents
can explain these differences (Chapter 10). Mg is lost from the oceans, and Si is added by
the reactions that take place in hydrothermal vent systems.
Turner et al. (1981) have shown a correlation between the residence time of an element
in the oceans and the partitioning of that element between rocks and seawater. They
defined the ocean–rock partition coefficient K Y by
0
200
400
600
800
1000
EQ
20°N
40°N
60°N
0
Ocean Data View
10
20
30
40
Al [nM]
Depth [m]
0
200
400
600
800
1000
EQ
20°N
40°N
60°N
0
Ocean Data View
0.5
1
1.5
2
Fe [nM]
Depth [m]
Figure 3.31
Section of Fe and Al off the coast of Africa in the Atlantic Ocean.
Table 3.11
Present Concentration (mol cm –2 of surface) of Major Components
of Seawater Compared with the Amount Added by Rivers over Past
100 Million Years
Na
Mg
Ca
K
Cl
SO 4
CO 3
NO 3
Present
129
15
2.8
2.7
150
8
0.3
0.01
Added by rivers
196 122
268
42
157 84
342
11
Excess added
67 107
265
39
7 76
342
11