119
Minor Elements in Seawater
The ratio of [H + ]/[K + ] is fixed; thus, the addition of HCl or KOH will return it to its original value as long as [Cl – ] and temperature are constant. The system is thus a pH stat rather
than a buffer as long as Cl – and temperature are constant and no phases completely disappear. This simple result suggests that the pH and the major ionic concentrations of seawater are controlled by clay exchange reactions. When Sillén made this suggestion, most
oceanographers were shocked, as they thought that the pH of the oceans was controlled by
the carbonate system and the clays acted only as the walls of the container. Experimental
studies yield K = 10 –6 to 10 –6.5 (25°C) for the reaction, while the ratio is 10 –6.2 in seawater. For
C eq (10
–7 M)
0
5
10
15
20
25
30
35
Sorbed Cu (mol 10
–18
cell
–1
)
0
2
4
6
8
10
Figure 3.26
The adsorption of Cu(II) to the surface of bacteria as a function of Cu.
Time (minutes)
0
250
500
750
1000
1250
1500
Sorbed Cu (mol 10
–18
cell
–1
)
4
5
6
7
8
9
Figure 3.27
The adsorption of Cu(II) to the surface of bacteria as a function of time.