Salinity, the amount of dissolved salts in water, is measured using several methods:
- Conductivity meters: These devices pass an electric current through a water sample and measure the electrical conductivity. Higher conductivity indicates higher salinity. This is the most common method used in modern oceanography and is often used in field applications.
- Refractometers: These instruments measure the bending of light as it passes through a water sample. The amount of bending is directly related to the salinity, allowing for quick and accurate readings.
- Hydrometers: These devices measure the density of the water. Higher salinity results in denser water, leading to different readings on the hydrometer.
- Laboratory analysis: This involves evaporating a known volume of water and weighing the remaining salts. This method provides highly accurate results but is time-consuming and less practical for field measurements.
Salinity is typically expressed in parts per thousand (ppt) or percentage (%). For example, the average salinity of seawater is about 35 ppt or 3.5%.
