Environmental Engineering Reference
In-Depth Information
COMPOSITION AND STRUCTURE OF OCEAN WATERS
OCEAN WATER CHEMISTRY
Ocean water is a weak cocktail of nearly 90 per cent of known elements, dissolved in 1·4
B km
3
of sea water or carried in suspension largely from terrigenous sources. Most
elements occur only as traces (less than one part per million) and just eleven account for
over 99 per cent of solutes - Cl, Na, Mg, K, Ca, Si, Cu, Zn, Co, Mn and Fe, in order of
mass. This is fairly similar to the compositional character of the lithosphere. The
elements are derived from continental crust erosion, sea water/crust interactions and
direct rainfall. They raise water density from 1·0 gm cm
−3
to an average of 1·03 gm cm
−3
with an alkaline pH of 7·8-8·4. The vast bulk of ocean water is chemically homogeneous
and stable, despite substantial active fluxes of water and minerals between adjacent
'spheres' and marine biosphere and sediment source. Exceptions occur
Figure 11.6
Some principles and controlling processes of sea
level.
