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What Is Salinity?

Salinity is the word used to refer to the occurrence of soluble salts in soil and water. It is a very general term describing the presence of levels of the different types of salt found such as sodium chloride, calcium sulfates and magnesium. Many people think of salinity only in terms of salt-water found in the oceans of the world, but salinity is also found to varying degrees in both freshwater and the soil.

  1. Ocean Salinity

    • Salinity in the ocean water is not always constant, and it changes as currents travel all over the world. Ocean saline levels tend to be higher in the deeper areas of the sea, and less in the more surface waters. Salinity is also lower around the edges of melting portions of polar ice fields, and near the equator where traditionally high precipitation levels dilute the saline level.

    Freshwater Salinity

    • Small amounts of dissolved salts are still found in river water, lake water, groundwater, rainwater and drinking water while still retaining the term "freshwater." Nearer to coaster areas, freshwater is often found to contain significant concentrations of salts derived from the sea when windy conditions or storms have lifted seawater inland or pulled seawater into rain-bearing clouds.

    Soil Salinity

    • Most soil, like freshwater, contains small amounts of salinity, but it is usually quite minor. Excessive saline content in the soil can kill crops and natural vegetation, making once nutrient rich soil practically lifeless. This sometimes occurs naturally due to over-run in coastal areas or in volcanic regions. Human involvement like over-farming, and the use of strong chemical fertilizers can also raise salinity to damaging levels.

    Estuaries

    • Some areas, known as estuaries, are special in that they are areas where salt and fresh water zones mix. In these areas, like where a river meets the ocean or swamps drain, the salinity level of the water constantly alters one way or the other. This special environment is home to many types of plants and animals who have adapted to live there in those conditions, with the only threat coming from storm surges or flooding that may occasionally disrupt the balance.

    Conclusion

    • There is more to salinity than just salt-water seas. Salinity is a very simple term for a far more complex natural function of the planet of which not many people are even aware.

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