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Give reasons why Ocean water is salty? | Class 7 NCERT - Our Environment ( GEOGRAPHY), SOCIAL SCIENCE


Give reasons why Ocean water is salty?

( Chapter 5: Water, Class 7- Our Environment ( GEOGRAPHY), SOCIAL SCIENCE)


Ocean water is salty due to a combination of natural processes and many factors that result in the accumulation of dissolved salts in seawater. 

The following are some primary reasons why ocean water is salty:

Chemical Weathering of Rocks:

Rainwater and surface water run over rocks and minerals on the Earth's surface. During this process, minerals containing ions like sodium (Na+) and chloride (Cl-) are gradually dissolved in water and flow in rivers, which eventually flow into the ocean.

Volcanic Activity: 

Volcanic eruptions release gases, including sulfur dioxide (SO2) and chlorine (Cl), into the atmosphere. These gases can react with water vapor to form acids like sulfuric acid (H2SO4) and hydrochloric acid (HCl), which ultimately go into the ocean via rainfall.

Hydrothermal Vents: 

On the ocean floor, hydrothermal vents release superheated water rich in minerals and metals. This water contains high concentrations of dissolved salts, including sulfides and chlorides.

Evaporation and Concentration: 

As seawater evaporates under the Sun's heat, the without containing salt water is removed, leaving behind the dissolved salts. This process, along with the fact that water vapor is less dense than air and rises, leads to the concentration of salts in the remaining seawater.

River Inflow: 

Rivers carry sediments, minerals, and ions from the land into the ocean. These substances contribute to the overall salinity of seawater.

Exchange with Sea floor :

Seafloor sediments can also release ions into the water through chemical interactions. Over time, these ions become part of the ocean's salt content.

Biological Processes: 

Marine organisms, such as certain types of algae and bacteria, can release salt into the water during their life cycles and as they decay.

From the above processes, ocean water becomes progressively saltier over time. This salinity is essential for the stability of marine ecosystems and the functioning of the global water cycle.

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