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Q 80- Ocean water salinity varies due to a variety of geographical and ecological reasons. Explain. (250 words)

  • Paper & Topic: GS I à Indian Culture

 

  • Model Answer:

 

  • Introduction:

 

  • The entire content of dissolved salts in sea water is referred to as salinity.
  • The amount of salt (in gm) dissolved in 1,000 gm (1 kg) of saltwater is used to calculate it.
  • At 0 degrees Celsius, the salinity of ocean water is normally around 35 parts per thousand.
  • This means that dissolved salts account for 3.5 percent of the total weight of ocean water.
  • The most prevalent dissolved salt in the sea is sodium chloride, sometimes known as common salt.

 

  • Body:

 

  • Salinity is influenced by a number of factors, including:

 

  • Controlling variables of oceanic salinity are elements that influence the quantity of salt in different oceans and seas.
  • Significant governing factors include evaporation, precipitation, river water influx, prevailing winds, ocean currents, and sea waves.

 

  • Salinity variations:

 

  • High salinity locations have a horizontal fluctuation.
  • Salinity is high in the landlocked Red Sea.
  • Salinity is quite high in hot and dry places where evaporation is significant.
  • Comparatively Regions with low salinity
  • Seasonal variations in salinity can be found in estuaries and the Arctic (fresh water coming from ice caps)

 

  • Pacific:
  • The Pacific Ocean's salinity variations are primarily attributable to its shape and wider area.

 

 

  • Atlantic:
  • Heavy rainfall, high relative humidity, cloudiness, and the calm air of the doldrums can be found near the equator.
  • Polar regions have extremely little evaporation and receive a considerable amount of fresh water from ice melting. This results in low salt levels; maximum salinity is found between 20° N and 30° N, and between 20° W and 60° W. In the direction to the north, it gradually declines.

 

  • Oceans of India:
  • Due to the influx of river water by the river Ganga, the Bay of Bengal is experiencing a low salinity trend.
  • The Arabian Sea, on the other hand, has a higher salinity due to significant evaporation and minimal freshwater influx.
  •  
  • Seas in the outskirts:
  • Despite its higher latitude, the North Sea has a higher salinity due to more saline water pushed in by the North Atlantic Drift.
  • Due to a massive input of river waters, the Baltic Sea has low salinity.
  • Due to significant evaporation, the Mediterranean Sea has a higher salinity.
  • The Black Sea, on the other hand, has an extremely low salinity due to the massive intake of fresh water from rivers.
  •  
  • Lakes and inland seas:
  • Because of the regular influx of salt by rivers flowing into them, the salinity of the inland Seas and lakes is extremely high.
  • Due to evaporation, their water gets increasingly saline.
  • The salinity of the Great Salt Lake (Utah, USA), the Dead Sea, and Lake Van in Turkey, for example, is extremely high.
  • Zones for combining cold and warm water
  • Because of the influx of melted water from the Arctic region, salinity reduces in the western sections of the northern hemisphere.
  •  
  • Salinity below the surface:
  • Salinity varies with depth, although this fluctuation is also influenced by latitudinal differences. Cold and warm currents have an impact on the decrease.
  • Salinity rises with depth at high latitudes. It rises to a maximum of 35 metres in the middle latitudes, then falls. Surface salinity is lower near the equator.
  •  
  • Salinity distribution vertically:
  • Salinity changes with depth, but how it changes is determined on the sea's location.
  • The loss of water to ice or evaporation raises salinity at the surface, whereas fresh water supply, such as from rivers, lowers it.
  • Because there is no mechanism for water to be 'lost' or salt to be 'added,' the salinity at depth is very much set. There is a significant difference in salinity between the ocean's surface and deep zones.
  • The dense water with a lower salinity sits above the dense water with a higher salinity.
  • Salinity rises with depth in general, but there is a separate zone termed the halocline (compare to thermocline) where salinity rises rapidly.
  • When all other conditions remain constant, increasing the salt of seawater causes it to become denser. Seawater with a high salinity sinks faster than water with a lower salinity. This results in salinity stratification.

 

  • Impact:

 

  • Compressibility, thermal expansion, temperature, density, insolation absorption, evaporation, and humidity are all affected by salinity.
  • It also has an impact on the ocean's composition and movement, as well as the distribution of fish and other marine resources.
  • Seawater density is influenced by salinity, which in turn influences ocean circulation and climate.
  • Some currents really shift direction seasonally due to the relationship between temperature, salinity, and density. The Indian Ocean is one place where this happens. Because salinity is linked to current movement, the salinity of the ocean is closely related to weather, even on land.
  • The type of organisms that exist in a body of water can be greatly influenced by salinity.
  • Furthermore, salinity is important in the water cycle and ocean circulation.
  • The intensification of the water cycle as a result of changes in ocean salinity during the last fifty years shows that it has increased by 4%, which is twice the pace predicted by models.
  • The earth's climate is kept in balance by stable salt levels in the oceans.

 

  • Conclusion:

 

  • Around 3 billion tons of salt are introduced to the oceans each year from the land.
  • Humans remove only a small portion of this salt for everyday ingestion.

 

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