SALINITY OF OCEAN WATER

SALINITY OF OCEAN WATER

WHAT IS SALINITY OF OCEAN WATER?

• It means the total dissolved salts content of in Sea /Ocean.
• Itis calculated the amount of salt dissolved in 1,000 gm of seawater.
• It is expressed as ‘parts per thousand’ or ppt.
• A salinity of 24.7 % is regarded as the upper limit.
• Isohalines are used on maps to show the salinity of different places.
• The average salinity of the ocean – 3.5% or 35 parts of salt in 1000 parts of water.

WHAT IS VERTICAL DISTRIBUTION OF SALINITY?

• Salinity changes with depth, depending upon the location of the sea.
• Salinity at the surface increases by the loss of water or decreased by the incoming of freshwaters.
• Salinity at depth is mostly fixed due to no water lost, or the salt added.
• The lower salinity water lies above the higher salinity water.
• In Halocline zone, salinity increases sharply.

WHAT IS HORIZONTAL DISTRIBUTION OF SALINITY ACROSS THE GLOBE?

High salinity regions

• In the landlocked Red Sea has around 41ppt.
• In hot and dry regions, due to high evaporation, the salinity sometimes 70ppt.

Low salinity regions

• In the estuaries and the Arctic Ocean, the salinity varies from 0 – 35ppt.

Pacific

• The salinity variation is mainly due to its shape and larger extent.

Atlantic

• The average salinity is around 36-37ppt.
• The equatorial region has a salinity of about 35ppt.

Indian Ocean

• The average salinity is 35ppt.
• The low salinity in the Bay of Bengal due to the influx of river water.
• Arabian Sea has higher salinity due to high evaporation and less water influx.

Marginal Seas

• The North Sea has higher salinity due to more saline water brought here.
• Baltic Sea and The Black Sea records low salinity due to large the influx of river.
• The Mediterranean Sea records higher salinity due to high evaporation.

Inland seas and lakes

• Their salinity is very high due to supply of salt by the rivers falling.
• More saline due to evaporation.
• Eg. The Great Salt Lake the Dead Sea, and the Lake Van in Turkey.

WHAT ARE THE FACTORS AFFECTING OCEAN SALINITY?

• Salinity, Temperature, and Density of water are interconnected.
• The salinity of water in the surface layer of oceans is influenced by:

• Evaporation
• Precipitation

• In the coastal areas salinity is influenced by the freshwater rivers.

• In the Polar areas the salinity is influenced freezing and melting of ice.
• Wind also influences the salinity of an area by moving water.
• Ocean currents contribute to changes the salinity.
• The change in the density or temperature also influences the salinity.