Geoscience Reference
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Table 7.2 Silica and erbium concentrations at different depths of the water column at a South
Atlantic station (Bertram and Elderfield, 1993)
SiO 3
Er
SiO 3
Er
(mmol kg 1 )
(pmol kg 1 )
(mmol kg 1 )
(pmol kg 1 )
Depth (m)
depth (m)
241
3.6
3.49
2332
57.8
6.09
331
6.3
3.66
2581
57.4
5.6
418
10.1
3.74
2832
58.8
5.18
495
13.8
3.87
3082
61.2
5.75
565
16.7
3.97
3330
65.6
5.89
741
25.6
4.14
3532
74.1
6.81
839
31.3
4.31
3737
84.7
6.71
1082
47
4.67
3945
95.9
6.53
1273
59.6
4.92
4202
104.7
7.44
1466
61.5
5.64
4458
108.4
8.1
1657
66.2
5.35
4700
110.5
7.3
1841
63.2
5.24
4995
111.3
7.99
2088
60.3
5.58
depth and explain the observations. Plot Er vs. Si and explain why an element of no
biological interest can be correlated to Si.
18. What thickness of CaCO 3 sediment spread over the entire surface of the ocean would
it take to remove 100 ppmv of CO 2 from the atmosphere? Use data from Appendix F
and a specific gravity of 2700 kg m 3 for CaCO 3 .
19. Explain why upwelling of deep water, such as under equatorial latitudes, reintroduces
CO 2 into the atmosphere.
20. What is the potential paleoceanographic use of the following records: (1)
18 O
δ
18 O in benthic foraminifers? (3) the
13 C difference
in pelagic foraminifers? (2)
δ
δ
between benthic and pelagic foraminifers of the same age?
21. Discuss the potential climatic changes and the depth of CCD upon (1) a nearly instan-
taneous surge in atmospheric CO 2 triggered by a massive sub-aerial volcanic eruption;
(2) the ensuing surge in riverine alkalinity flux resulting from the weathering of the
lava flows; (3) an increase in primary productivity; and (4) a strong decrease in oceanic
thermohaline convection.
22. The solubility of calcite varies in the ocean with depth. Since [Ca 2 + ] is essentially
constant over the residence time of this element (
1 My), this variation is expressed as
CO 2 3
90 e 0.16 ( z 4 ) , where z is the depth in kilometers and solubility is expressed
=
mol kg 1 . Using the assumption that a change in the depth of the CCD is nearly
equivalent to a change in the depth of the lysocline (saturation level) and that the
relative change of HCO 3 can be neglected with respect to the relative change of
in
μ
CO 2 3 , estimate the relative change of P CO 2 associated with a shallowing of the
CCD by 1 km. (Hint: consider using equations (7.2) and (7.40) ) .
 
 
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