Geoscience Reference
In-Depth Information
0
1
C
Inorganic
Nitrate
O
Dissolved
2
3
4
5
0
1
P
2
Al
Si
3
4
5
0
Na
K
Ca
1
2
3
Cl
4
5
0
1
Mg
Fe
S
2
3
4
5
Concentration (arbitrary units)
Figure 7.15
Elements used by biological activity, such as C, N, P, Si (nutrients), are depleted at the surface.
Residual major elements, such as Na, Cl, K, Mg, are not affected by biological activity. Aluminum
is a detrital element introduced into the thermocline by airborne particles. Dissolved oxygen is
equilibrated with atmospheric gases near the surface but is significantly depleted below the
thermocline as a result of the oxidation of falling organic debris.
Redfield-Ketchum-Richards (RKR) reaction, which leads to the production of biological
material:
106CO 2 +
16HNO 3 +
H 3 PO 4 +
122H 2 O
(
CH 2 O
) 106 (
NH 3 ) 16 H 3 PO 4 +
138O 2
This reaction is endothermic and uses solar energy (photons) to produce carbon and nitro-
gen in a highly reduced state that later may liberate large amounts of chemical energy. The
elements used by biological activity, such as C, N, P, and Si, are depleted in surface water
and are known as nutrients. They contrast with the residual major elements, such as Na,
Cl, K, and Mg, which are not affected by biological activity ( Fig. 7.15 ) . In the section on
 
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