Geology Reference
In-Depth Information
Table 5.4 Volume of oceans and seas. Adapted from (Ency-
clopaedia-Britannica, 2007)
Volume, Mkm
3
Name
Pacific Ocean
without marginal seas
707.6
with marginal seas
723.7
Atlantic Ocean
without marginal seas
324.6
with marginal seas
354.7
Indian Ocean
without marginal seas
291
with marginal seas
291.9
Arctic Ocean
17
Australasian Central Sea
9.9
Gulf of Mexico and Caribbean Sea
9.6
Mediterranean Sea and Black Sea
4.2
Bering Sea
3.33
Sea of Okhotsk
1.3
Hudson Bay
0.16
North Sea
0.05
Baltic Sea
0.02
The world ocean
1,370
ocean circulation is responsible for the transportation of enormous volumes of cold
waters, the movement of saltwater from the North Atlantic to the Northern Pacific,
and for the bringing of warmer and fresher water in return (see Sec. 6.6.4.1 for more
details). Aside from being a huge food reservoir, oceans can be a source of pure
water (following desalination), chlorine and bromine. Salinity prevents seawater
from having more economic potential and is thus frequently considered to be more
of a liability than an asset.
5.4.1.1 The composition of the seas
Despite their overall size, the oceans are su
ciently uniform to make the description
of their chemical nature fairly straightforward. Studies have shown that the relative
compositions of major components are as follows: Na
+
, Mg
2+
, Ca
2+
, K
+
, Cl
,
SO
4
, Sr
2+
, HBO
3
, CO
2
3
, B(OH)
3
, B(OH)
4
, F
and are constant (Culkin,
1965; Brewer, 1975; Pilson, 1998; Millero, 1996). The first six ions make up 99.4%
of the dissolved salts (see Table 5.5). Regarding minor elements, one of the most
accepted seawater compositions is the compilation of Quinby-Hunt and Turekian
(1983), listed in Table 5.6.
Most of the chemical ions in the ocean are brought from river waters, which in
turn receive them from rocks that have suffered weathering. An average composition
of river waters given by Livingstone (1963) is listed in Table 5.8. As can be seen
in Table 5.5 and Table 5.8 river and ocean chemical compositions are remarkably
different. This is because the majority of ions found in seawater have residence
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