Geology Reference
In-Depth Information
Figure 8 A profile of molecular oxygen in the North Pacific Ocean
(Data from Bruland, 1980.
13
)
with depth to develop an oxygen minimum zone. Thereafter, the O
2
concentration in deeper waters begins to increase because these waters
originated from Polar Regions. They were cold and in equilibrium with
atmospheric gases at the time of sinking, but subsequently lost little of
the dissolved O
2
because the flux of organic material to deepwaters is
relatively small.
The dissolved O
2
content of seawater has a significant control on the
redox potential, often designated in environmental chemistry by pe (see
also Chapter 3). This is defined with reference to electron activity in an
analogous fashion to pH and thus
pe
¼
log
f
e
g
The relationship between pe and the more familiar electrode potential E
or E
H
is
F
2
:
303RT
E
pe
¼
ð
4
:
3
Þ
