84
Chemical Oceanography, 4th Edition
ocean has been estimated to be 4 × 10 11 g yr –1 . High concentrations of B in rain probably
result from distillation from the sea surface B(OH) 3 , which has a high volatility.
2.6.7 anoxic basins
A number of anoxic basins exist (Black Sea, Cariaco Trench) in the world oceans (Richards,
1965). The SO 4
2– /Cl ratios in these basins are quite low because of bacteria using SO 4
2– as a
source of O 2 giving off H 2 S. The H 2 S is lost by precipitation of FeS 2 and other sulfides (ZnS,
CuS, etc.). Further discussion of these anoxic basins is found in Chapter 10.
2.6.8 Freezing
Sea ice has a higher (SO 4
2– /Cl) ratio than sea water (because of SO 4
2– incorporation into
ice). Waters in the North Pacific in the minimum temperature layer (formed by melting ice)
have been shown to be deficient in SO 4
2– . Differences may also occur in Ca/ Cl because of
precipitation of CaCO 3 in sea ice.
2.6.9 interstitial Waters
Interstitial pore waters differ appreciably from sea water in some major components. The
Cl – is within ±1% of overlying water, with large variations from one locality to another.
Changes in Ca 2+ can result from the dissolution of CaCO 3 caused by the oxidation of plant
material (giving CO 2 ), while changes in SO 4
2– can occur because of the production of H 2 S
by bacteria.
Changes in K + and other cations can occur by exchange with clay minerals. Mg may be
depleted from uptake by chlorite or reaction with CaCO 3 to form dolomite. In contrast,
K + is enriched because of the hydrolysis of feldspars. Sediment chemistry is discussed
Normalized Calcium (mM)
10.30
10.34
10.38
10.42
Depth (m)
0
1000
2000
3000
4000
5000
Figure 2.23
Depth profile of the normalized calcium in the North Pacific.
Chemical Oceanography, 4th Edition
ocean has been estimated to be 4 × 10 11 g yr –1 . High concentrations of B in rain probably
result from distillation from the sea surface B(OH) 3 , which has a high volatility.
2.6.7 anoxic basins
A number of anoxic basins exist (Black Sea, Cariaco Trench) in the world oceans (Richards,
1965). The SO 4
2– /Cl ratios in these basins are quite low because of bacteria using SO 4
2– as a
source of O 2 giving off H 2 S. The H 2 S is lost by precipitation of FeS 2 and other sulfides (ZnS,
CuS, etc.). Further discussion of these anoxic basins is found in Chapter 10.
2.6.8 Freezing
Sea ice has a higher (SO 4
2– /Cl) ratio than sea water (because of SO 4
2– incorporation into
ice). Waters in the North Pacific in the minimum temperature layer (formed by melting ice)
have been shown to be deficient in SO 4
2– . Differences may also occur in Ca/ Cl because of
precipitation of CaCO 3 in sea ice.
2.6.9 interstitial Waters
Interstitial pore waters differ appreciably from sea water in some major components. The
Cl – is within ±1% of overlying water, with large variations from one locality to another.
Changes in Ca 2+ can result from the dissolution of CaCO 3 caused by the oxidation of plant
material (giving CO 2 ), while changes in SO 4
2– can occur because of the production of H 2 S
by bacteria.
Changes in K + and other cations can occur by exchange with clay minerals. Mg may be
depleted from uptake by chlorite or reaction with CaCO 3 to form dolomite. In contrast,
K + is enriched because of the hydrolysis of feldspars. Sediment chemistry is discussed
Normalized Calcium (mM)
10.30
10.34
10.38
10.42
Depth (m)
0
1000
2000
3000
4000
5000
Figure 2.23
Depth profile of the normalized calcium in the North Pacific.