the average salinity of oceanic water is -

The Correct Answer is 35%o.

Key Points

• Sea water salinity is expressed as a ratio of salt (in grams) to liter of water.
• In sea water there is typically close to 35 grams of dissolved salts in each liter.
• It is written as 35‰ The normal range of ocean salinity ranges between 33-37 grams per liter (33‰ - 37‰). 
• Salinity means the total content of dissolved salts in Sea or Ocean.
  Salinity is calculated as the amount of salt dissolved in 1,000 gm of seawater.
• It is generally expressed as ‘parts per thousand’ (ppt).
  A salinity of 24.7 % has been regarded as the upper limit to fix ‘brackish water’.
• It is a significant factor in deciding several characteristics of the chemistry of natural waters and biological processes.

Additional Information

• 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 regions, the surface salinity is influenced by the freshwater flow from rivers.
  • In the Polar region, the surface salinity is influenced by the processes of freezing and melting of ice.
  • The wind also influences the salinity of an area by moving water to other areas.
  • The ocean currents contribute to the salinity variations.
  • The change in the density or temperature influences the salinity of water in an area.
• Share of different salts
  • Sodium chloride — 77.7%
  • Magnesium chloride—10.9%
  • Magnesium sulphate —.4.7%
  • Calcium sulphate — 3.6%
  • Potassium sulphate — 2.5%