Project cost ($):
This science project requires an electric aquarium heater and water.
The salinity of the world's seas and oceans varies due to a number for factors including temperature and water depth. In this science fair project, you will explore how salinity is affected by temperature, to understand why salinity varies throughout the world's oceans.
Determine the relationship between temperature and salinity.
Salinity refers to the amount of salt that is dissolved in water. Temperature change is most common in surface waters, due to exposure to the sun. During the day, water near the surface of the sea is warmed up due to heat from the sun. At night, the water cools down as it loses heat. This is in contrast to water found in the depths of the ocean, where the temperature is cooler and more consistent. Salinity decreases with an increase in temperature, in part due to a change in density. Warm water is less dense than colder water, meaning that water molecules are further apart from each other in warmer waters. Water that is more dense is saltier. The two factors of density and temperature are interrelated and together they affect the amount of salinity in the water.
While it is true that warmer waters have lower salinity than cooler waters, a greater amount of evaporation occurs at higher temperatures. You would expect that the salinity would increase, as evaporation increases, leaving behind more concentrated salt water.
Given this fact, why wouldn't water nearer the surface of our oceans have a higher salinity?
Questions & Answers
What is salinity?
Salinity refers to the saltiness, or the amount of salt dissolved in water.
Make it Your Own
Investigate if there is a relationship between salinity and geographical location.