Pakshal SecretryAIR 8 · CSE 2025 · 242 wordsTheir whole copy
Opening
There is much variation in salinity across the ocean, while the tropical oceans have very high salinity, in the polar region salinity is significantly lower.
Body · points
Reasons for Salinity Variation
(1) Lattitude → Higher lattitude - ice → low Salinity
(2) Rainfall → Equator → High Rainfall → low salinity
(3) Evaporation → Tropical Region - High evaporation - High Rainfall
④ Role of ocean current → eg Peruvian current → less saline water
⑤ Temperature and pressure conditions → more temperature → more evaporation
⑥ Role of wind → carries saline water to non saline areas
⑦ Role of fresh water inflow → eg Rivers → Bay of Bengal less saline than Arabian Sea
⑧ Role of land boundary → Makes water less saline by water input
Impact on Circulation
(1) Thermohaline circulation → Due to difference in salinity → Saline water → Dense → moves down → space taken by fresh water → circulation eg AMOC - due to salinity differences
(2) Movement of water from tropic to temperate region → To redistribute salinity differences
Impact on Marine Diversity & Ecosystem
(1) Salinity specific species Eg no Coral → only in fresh water
(2) Provides condition for survivability of species eg saline water fishes
(3) Mixing of water → Most productive & biodiverse zones of world
(4) Helps in regulation of temperature, pressure etc in ocean
Close · a summary
Eg Thermo Haline circulation
Thus; salinity variation impacts marine and human living in various ways.