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Why is saltwater salty?
Question Date: 2007-01-27
Answer 1:

Salt water of saline water is water that contains a significant concentration of dissolved salts.

From saltwater

The reason why salt water is salty is because when rain falls on terrestrial rock (mountains, etc.) it contains some dissolved carbon dioxide from the surrounding air. This causes the rainwater to be slightly acidic due to carbonic acid (which forms from carbon dioxide and water). The rain erodes the rock and the acid breaks down the component parts of the rock and carries it along in a dissolved state. The ions in the runoff are carried to the streams, rivers, and estuaries to the ocean. Many of the dissolved ions are used by organisms in the ocean and are removed from the water. Others are not reactive and are not used up and are left for long periods of time where their concentrations increase over time. The two ions that reside in greatest quantity and are removed most slowly of the major ions in seawater are chloride (Cl-) and sodium (Na+). These two make up over 90% of all dissolved ions in seawater.

River water has higher concentrations of bicarbonate, potassium, calcium, and sulfates. These elements however are used or absorbed by organisms or react with other things in the water so that they are no longer present in the ocean in large quantities. On the other hand, river water contains almost no sodium or chloride ions, but these do not get removed by organisms or by chemical reaction, so they just keep on building up and getting more concentrated.

Anyway, ocean water contains the following ions in the indicated concentrations. These make up over 99.3% of everything dissolved in seawater.

Chloride 19.353
Sodium 10.79
Magnesium 1.297
Sulfate 2.712
Calcium 0.4123
Potassium 0.399
All values listed are grams per kilogram of seawater (g/kg) at a salinity of 35 parts per thousand (ppt).



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