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The composition of seawater
On average, seawater in the world's oceans has a salinity
of about 3.5% (35 g/L). This means that every kilogram
(roughly one liter by volume) of seawater has
approximately 35 grams of dissolved salts -predominantly
Sodium Chloride ions: Na+, Cl−. Seawater contains more
dissolved ions than all types of freshwater.
Although the vast majority of seawater has a salinity
varying between 3.1% and 3.8%, seawater is not uniformly
saline throughout the world. Where mixing occurs with
fresh water runoff from river mouths or near melting
glaciers, seawater can be substantially less saline. The
most saline open sea is the Red Sea, where high rates of
evaporation, low rates precipitation & river inflow, and
confined circulation result in unusually salty water.
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DID YOU KNOW:
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Most of this salt in the sea has been released from volcanic activity or extracted from cool, igneous rocks!!! |
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The pH of seawater is limited to the range 7.5 to 8.4.
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Seawater composition (by mass) (salinity = 35) |
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Element
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% |
Element
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% |
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Oxygen
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85.84 % |
Sulfur
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0.091 % |
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Hydrogen
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10.82 % |
Calcium
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0.04 % |
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Chloride
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1.94 %
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Potassium
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0.04 % |
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Sodium
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1.08 %
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Bromine
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0.0067 % |
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Magnesium
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0.1292 %
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Carbon
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0.0028 % |
96.7% of the contents of sea water is pure water. The
majority of what remains is composed of Sodium Chloride,
however, the presence of several trace elements, despite
their small presence, is particularly important.
Seawater does not remain in one position. Tidal and
oceanic currents move great masses of it around the world.
As a result, the amounts of trace elements and minerals
are not constant and depend on factors such as
geographical location, volcanic activity, pollution, etc.
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