Salinity refers to the saltiness or amount of salt dissolved in a body of water, such as saline water
. It is usually measured in g/L or g/kg (grams of salt per liter or kilogram of water) and is a crucial factor in determining many aspects of the chemistry of natural waters and biological processes within them
. Salinity is also a thermodynamic state variable that governs physical characteristics like the density and heat capacity of the water
. Salinity is important for several reasons:
- It can affect the health, environmental, and economic aspects of water bodies, making water unsuitable for drinking, food production, and various domestic and industrial uses
- It can be a chemical stressor in the aquatic environment, as fluctuating levels of salinity can affect aquatic biological organisms adapted to prevailing salinity concentrations
- Salinity is one of the primary factors used to identify whether a given study site is part of an estuarine or coastal system
Salinity levels in bodies of water can be classified as follows
:
- Fresh water (< 0.05%)
- Brackish water (0.05–3%)
- Saline water (3–5%)
- Brine (> 5% up to 26%–28% max)
In the open ocean, the range of salinity observed is from 33 to 37 practical salinity units (psu)
. Salinity can be measured using a salinometer, which calculates the amount or weight of salt present in a specific volume of water
