Salinity refers to the concentration of dissolved salts in water, typically measured in parts per thousand (ppt). The average ocean salinity is about 35 ppt, meaning 35 grams of salts per kilogram of seawater.
Atlantic Ocean has higher salinity, especially in the subtropics, reaching up to 37 ppt. On the other hand, Baltic Sea has lower salinity, around 10 ppt due to significant freshwater inflow from rivers.
Red Sea has one of the highest salinities, approximately 41 ppt, due to high evaporation and low freshwater input. On the contrary, Gulf of Bothnia, part of the Baltic Sea, experiences salinity as low as 2-3 ppt.
Table of Contents
Causes of Ocean Salinity
1- Evaporation:
Increases salinity by removing water and leaving salts behind.
High in subtropical regions with hot climates, such as the Mediterranean Sea.
2- Freshwater Inflow:
Dilutes salinity where rivers and precipitation contribute large amounts of freshwater.
Lower in regions like the mouths of large rivers (e.g., Amazon River).
3- Ice Formation and Melting:
Ice formation increases salinity as salts are excluded from ice crystals.
Melting ice decreases salinity by adding freshwater.
4- Circulation Patterns:
Ocean currents redistribute saline water, affecting regional salinity.
For example, the Gulf Stream carries salty water from the Caribbean to the North Atlantic.
5- Submarine Volcanic Activity:
Adds salts to the ocean from underwater volcanic eruptions and hydrothermal vents.
6- Human Activities:
Runoff from agriculture and urban areas can increase local salinity through the addition of dissolved salts.
Understanding these factors is crucial for marine biology, climate studies, and oceanography.
