Seawater: Earth's Primary Natural Source of Salt
Seawater is one of the most abundant natural sources of salt on Earth, covering approximately 71% of the planet's surface. It contains dissolved minerals, with sodium chloride (NaCl) making up about 85% of the total salts. The average salinity of seawater is roughly 3.5%, or $35$ grams of salt per liter of water. This dissolved salt originates from the weathering of rocks on land, carried by rivers into the oceans over millions of years.
Understanding this requires recalling basic salt solubility: NaCl is highly soluble in water, allowing it to dissolve easily and form a uniform solution in seawater.
Key Fact: Without evaporation, this salt would remain dispersed, but natural processes concentrate it for human use.
- Seawater's salt content varies slightly by location; for example, the Red Sea has higher salinity at around 4% due to higher evaporation rates.
- This makes seawater a renewable yet vast reservoir, estimated to hold about 50 quintillion tons of dissolved salts.