Salinity can be understood as the concentration of dissolved salts in ocean-water. It is a crucial factor impacting the various other phenomenon like ocean circulation, climate, and marine ecosystems. Salt Budget is the cycle of circulation of salts from sea-water to lithosphere to atmosphere and then back to sea-water to different extents. Salinity Budget is influenced by both Natural Factors and Anthropogenic Factors.

Natural Factors

• Evaporation: High evaporation rates in warm tropical and subtropical regions increase salinity by removing water and leaving salts behind. For example, the Red Sea and Persian Gulf have high salinity due to high evaporation rates.
• Precipitation: Equatorial zones experience high rainfalls due to which ocean-water gets diluted and therefore salinity decreases.
• River Discharge: Major rivers, such as the Amazon, discharge large volumes of freshwater into the ocean, which dilutes the sea-water when these rivers drain out in sea and henceforth salinity decreases.
• Ice Melting at poles: When ice at poles melt, it dilutes ocean-water, reducing its salinity.
• Ocean currents: Due to ocean currents, the salinity of water often varies regionally and gets redistributed. For instance, the Gulf Stream transports saline water from the Atlantic to the higher latitudes.
• Temperature: Temperature influences salinity of water both directly and indirectly as warmer waters can hold more salts. However, temperature also influences evaporation rates, indirectly affecting salinity.

Anthropogenic Factors

• Climate Change: Increasing global average temperatures due to various human activities lead to altered evaporation and precipitation patterns, influencing salinity.
• Dam Construction and Water Diversion: Dams and water diversion projects reduce the flow of freshwater into the ocean, potentially increasing salinity in coastal areas.
• Pollution: Industrial waste discharge and runoff of fertilizers from fields due to rain into sea-water leads to increase in salinity.

  The salinity budget of the ocean is a dynamic equilibrium influenced by both natural processes and human activities. Effective management and mitigation strategies are essential to address both the natural and anthropogenic effects on ocean salinity. There is a need for continuous monitoring and research to safeguard ocean health.