Sea water becomes salty because of the salt dissolved in it. This process occurs because over time, rainwater and river water carry minerals from land to the sea. Sea water also contains salt which is removed from rocks on the seabed through the weathering process.
When water flows into the sea, salt from rainwater, river water, and weathering rocks dissolves in seawater. When seawater evaporates through the evaporation process, the water turns into steam, while the salts remain in the water. Therefore, the more seawater that evaporates, the higher the salt concentration in it, making the seawater taste salty.
On average, the salt content in seawater is about 3.5% by weight per volume (35 grams per liter). Although most sea salt is sodium chloride (NaCl), sea water also contains various other salts and minerals in smaller amounts.
Sea Salt Comes From
Salt in the sea comes from various sources, and natural processes that occur in and around the ocean. Here are some of the main sources of salt in the sea:
1. Rock Weathering
Salt comes from rocks on land that go through a weathering process. Rainwater and river water carry minerals, including salt, from the land to the sea.
2. Volcanic Activity
Volcanic activity can release minerals and salts into the sea. When a volcano erupts, volcanic material can mix with sea water and contribute to the mineral content in the sea.
3. Geochemical Processes
Several geochemical processes in the earth can release salt into seawater. One example is the hydrothermal process on the seabed, where hot water from below the earth's surface carries minerals into the sea.
4. Activities of Marine Organisms
Marine organisms such as microorganisms, algae, and sea animals can also contribute to the salt content in the sea through their life cycles. For example, dead organisms can produce salts as they decompose.
5. Ocean Water Cycle
Sea water continues to experience cycles of evaporation (evaporation) and precipitation (rain). When seawater evaporates, salts remain in it, increasing the salt concentration in the sea.
These sources contribute to the salt content in seawater, and over time, these processes form unique ecosystems in the sea and give seawater its salty characteristics.
Geochemical Processes
Geochemical processes that contribute to salt content in the sea involve the interaction of minerals in the earth with sea water. Some of these processes include:
1. Hydrothermal Ventilation
On the seabed, there are areas known as "black smokers" or hydrothermal vents. The hot water that emerges from this source contains various minerals, including metals such as iron, copper and other metal sulfides. This process involves seawater seeping into the earth's crust, heating and dissolving minerals, and then expelling them back into the sea. The salts dissolved in hot water are included in the sea salt content.
2. Subduction Process
When an oceanic plate meets a continental plate or another oceanic plate, the oceanic plate can be pushed into the Earth's mantle in a process called subduction. At a certain depth, pressure and temperature increase, causing material from the oceanic plates to dissolve and form magma. This magma can then reach the surface through volcanic eruptions and release minerals, including salt, into sea water.
3. Weathering of Rocks Below the Surface
Some rocks below the earth's surface contain minerals such as halite (rock salt) which can dissolve in water. This weathering process occurs when groundwater seeps into layers of rock, dissolves the minerals, and carries them to the surface. This salt-containing water can then flow into the sea via rivers or the percolation process.
4. Mineral Dissolution
This process involves the dissolution of minerals from rocks on land and their transport by water to the sea. Minerals such as sodium chloride, magnesium, calcium and potassium can be dissolved in rainwater, river water or groundwater, and then carried to the sea. This process makes a significant contribution to the sea salt content.
Through complex interactions between these various geochemical processes, the sea becomes a habitat rich in minerals and salts. This not only influences the physical properties of seawater, but also provides the basis for diverse and unique marine life.
Conclusion:
The origin of sea salt is rainwater. Rainwater that falls to earth has acidic properties because it contains carbon dioxide (CO2) which comes from the air. This acidic rainwater will then flow to the surface of the earth and seep into the soil. In the soil, rainwater will dissolve existing minerals, including salt. Salt that dissolves in rainwater will then be carried away by river water and eventually empty into the sea.
This process occurs continuously for millions of years, so that over time the salt content in the sea becomes higher and higher. The sea salt that is formed will then settle on the seabed. This salt deposition process will take place more quickly in areas that have a hot and dry climate.
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