Which Type of Seawater Has the Greatest Density?

The density of seawater is affected by both salinity and temperature.

According to Dr. J. Floor Anthoni of The Marine Conservation and Education Centre in Leigh, New Zealand, the density of seawater is determined by two factors: the amount of salt dissolved in it and its temperature. The higher the density of water, the more buoyancy it demonstrates.

Density and Salinity

According to the Marine Science Center at the University of California at Los Angeles (UCLA), water is a solvent that is able to retain large amounts of salt. The more salt that is dissolved in water, the higher its salinity and the greater mass it has. Since more "stuff" is dissolved in it, water with higher salt content is heavier and more dense.

Density and Temperature

According to Jennifer Bergman of the National Earth Science Teachers Association, density is impacted more by temperature than by salinity; the colder the water, the more dense it is. Seawater is colder and more dense at greater depths. Oceans are layered with the coldest, most dense layers on the bottom and the lighter layers towards the top.

Examples

The open oceans have an average salinity of about 35 grams of salt per thousand milliliters of water, expressed as 35 o/oo, says the UCLA Marine Science Center. It lists the Red Sea as having a high salinity of 40 o/oo, the Black Sea as a low salinity of 18 o/oo and the Baltic Sea as a very low 8 o/oo. The famously dense Dead Sea has a salinity of 290 o/oo.

References

• Sea Friends: The Chemical Composition of Seawater
• University of California Los Angeles; Marine Science Center: Seawater Density and Salinity
• Windows to the Universe: Density of Ocean Water

Resources

• UCLA Marine Science Center: Home