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The hydrosphere (liquid)
Description of the hydrosphere
Most of the liquid layer of the earth consists of water, a unique feature
of our planet. Covering some 71% of the earth's surface, this water is
mostly contained in salty oceans that have an average depth of a little
over two miles. The remainder of the water on the earth is tied up in ground
water and glaciers. Only a minute fraction circulates in the rivers or
in the atmosphere.
| Total water on Earth |
100 % = 336x106 cubic miles = 1370x106
cubic km |
| Total water in oceans |
97.25% |
| Total water on land |
2.75% |
| Glaciers |
2.05% |
| ground
water |
0.68% |
| lakes
and streams |
0.02% |
| soils |
0.005% |
| Total water in atmosphere |
0.001% |
The hydrosphere is critical in heat distribution on the earth and hence
influences climate and weather. It is a major habitat for life. For example,
algae in the ocean produce some 90% of the oxygen in the atmosphere. Critical
for agriculture and manufacture, it also provides recreation and transportation
and contains vast stores of resources. The hydrosphere also shapes the
land, cleanses the atmosphere and stores and degrades pollutants.
Origin of the hydrosphere
The origin of the water itself is tied to the outgassing process.
The main gaseous component given off by volcanos is steam, which condenses
to form the water in the oceans. The dissolved salts and other chemicals
in the oceans and other water bodies have a varied origin; some come from
outgassing, while most of are derived from rocks being dissolved by water
(both newly forming rocks in the oceans, as well as the older continental
materials). From there, these chemicals are transported to the oceans by
rivers and ground water. Others come from the atmosphere or are added by
life.
| DISSOLVED MATERIAL |
Ave. Concentration at 35 0/00 |
% of dissolved materials |
| Chloride
Cl- |
19.35 |
55.29 |
| Sodium
Na+ |
10.76 |
30.74 |
| Sulfate
SO4-2 |
2.71 |
7.75 |
| Magnesium Mg+2 |
1.29 |
3.70 |
| Calcium
Ca+2 |
0.41 |
1.18 |
| Potassium K+ |
0.39 |
1.11 |
| Bicarbonate HCO3-2 |
0.14 |
0.41 |
| Bromine
Br- |
0.067 |
0.19 |
| Carbonate CO3-2 |
0.016 |
0.05 |
| Strontium Sr+2 |
0.08 |
0.02 |
| Silica
SiO2 |
0.006 |
0.02 |
| Boron
B |
0.004 |
0.01 |
| Fluorine
F |
0.001 |
0.003 |
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