Salinity

Salinity is the measure of all the salts dissolved in water. Salinity is usually measured in parts per thousand (ppt or ‰). The average ocean water salinity is about 35 ppt which means that there are 35 grams of dissolved salts in 1 kilogram of water.

Overview

Salinity is an important factor in determining many aspects of the chemistry of natural waters and of biological processes within it, and is a thermodynamic state variable that, along with temperature and pressure, governs physical characteristics like the density and heat capacity of the water.

Measurement

Salinity can be measured using a salinometer, a device that measures the salinity of a solution through an electrochemical process. The salinity is then read out in Practical Salinity Units (PSU), which are a standard for measuring the concentration of dissolved salts in water.

Effects on Aquatic Life

Salinity levels can affect the survival of aquatic organisms. Most fish and other aquatic species can only tolerate a certain range of salinity. Changes in salinity levels can create stressful conditions for aquatic life and can even be lethal.

Salinity in Different Water Bodies

The salinity of water bodies can vary greatly. For example, the Dead Sea has a salinity of about 34%, which is about ten times saltier than normal sea water. On the other hand, freshwater bodies like lakes and rivers have a very low salinity, usually less than 0.5%.

See Also

• Oceanography
• Hydrology
• Water Quality

Salinity Resources
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