WQM: Conductivity to Salinity Conversion

Salinity

• Salinity is a measure of the mass of dissolved salts (ionic constituents) in a given mass of solution and usually expressed as parts per thousand (ppt).
• Ions commonly found in water include calcium, magnesium, potassium and sodium cations and bicarbonate, carbonate, chloride, nitrate, and sulfate anions.
• Conductivity is a good measure of salinity in water. Other indirect measures are water density, sound speed, and refractive index. All can be used to calculate salinity.

Calculations

1. Collect conductivity (uS/cm) and water temperature (C) data.
2. Use spreadsheet or calculator to convert conductivity and temperature data to salinity value.
3. Equations used are based on the practical salinity scale and are valid for surface waters with salinity between 2 and 42 ppt. Please view the source to this document and consult Standard Methods for the Examination of Water and Wastewater if you have questions or concerns.