EarthWords is an on-going series in which we shed some light on the complicated, often difficult-to-pronounce language of science. Think of us as your terminology tour-guides, and meet us back here every week for a new word!

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The EarthWord: Salinity

Definition:

• Feeling a little salty over our bad jokes? Then this EarthWord’s for you! Salinity is the measure of dissolved salts in water.

• This accounts for all salts, not just sodium chloride (table salt).

Etymology:

• Salinity comes from the Latin sal, which meant “salt.”

Use/Significance in the Earth Science Community:

• Salinity is an important measure for water quality, as well as aquatic ecosystems. Many organisms require certain salinity levels to survive, and changes to that salinity, either due to natural cycles or manmade activities can affect them.

• In addition, salinity is one of the things that affects water’s density, and therefore how the water moves. Water with low salinity, such as freshwater, has a much lower density than water with high salinity (that’s why you float more easily in salt water).

USGS Use:

• USGS studies salinity as one of its measurements for the Office of Water Quality.

• In addition, salinity in surface water is measured at many streamgages, usually expressed as "conductance.”

• Last, but not least, groundwater salinity is an important area of study for USGS, especially as saltwater intrusion occurs in aquifers used for drinking water and irrigation.

   

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