Temperature doesn't directly change the amount of salt (salinity) in water. However, it significantly impacts how salinity is measured and influences water density, which affects water column stratification.
The Relationship Between Temperature and Salinity Readings
Several sources highlight that temperature affects the reading of salinity, not the actual salinity itself. A hydrometer or refractometer, commonly used to measure salinity, is sensitive to temperature. This Reef2Reef thread points out that increasing temperature decreases the hydrometer reading, while decreasing temperature increases the reading. This is because temperature alters water density; denser water gives a different reading than less dense water, even if the salt concentration remains the same. This Saltwaterfish.com forum discussion also emphasizes this point: the instrument reading changes, but the salinity remains constant if the salt concentration is unchanged. To get an accurate salinity reading, temperature compensation is often necessary.
Temperature's Indirect Influence on Salinity: Density and Stratification
While temperature doesn't directly alter salinity, it plays a crucial role in water density. This University of Hawai'i website explains that water with different temperatures (and salinities) forms layers due to density differences. Colder, saltier water is denser and sinks, while warmer, less salty water rises. This stratification can indirectly affect the distribution of salinity in a water body. For instance, melting ice (lower salinity, lower temperature) can initially create a layer of lower salinity water on top of saltier water, resulting in apparent changes in the measured surface salinity.
Temperature and the Solubility of Salt
Another factor to consider is the slight effect of temperature on salt solubility. As mentioned in the provided text, “As the temperature of water decreases, the amount of salt that can be dissolved in it also decreases.” This means that colder water can hold slightly less dissolved salt than warmer water. However, this effect is generally minor compared to the impact of temperature on density and measurement readings.
In Summary
Temperature does not directly change the amount of salt in water (salinity). It primarily influences salinity readings by affecting water density and, to a lesser extent, the solubility of salt. Accurate salinity measurement requires temperature compensation.
