Chapter 16, Problem 1TYC

To determine

The proportion of Earth’s surface oceans covers, the average salinity of ocean water and the way in which density, salinity and temperature are related in each layer of ocean water.

Answer to Problem 1TYC

Oceans cover $71\%$ proportion of the Earth’s surface and the ocean water have $3.5\%$ of salts in it. Water temperature decreases with depth, and density increases slightly at lower temperatures and higher salinities. Therefore, deep water tends to be denser, colder, and saltier than the surface water.

Explanation of Solution

The ocean’s water form layers, with dense water at the bottom. The density of sea water is determined by temperature and salt content. Deep water is dense because it is cold. Surface water is generally salty because of evaporation. But the increase in density due to evaporation is more than offset by the decrease in density due to warming.

Approximately $71$ percent of Earth’s surface is covered by oceans that have an average depth of $3800\text{m}$. The salinity is the total amount of salt dissolved in seawater. The total constituents in ocean salinity are chloride, sodium, sulfate, bicarbonate, potassium, calcium and magnesium that make the average seawater salinity $3.5\%$.

The salinity, temperature and density are related in each layer of ocean on following ways:

Salinity: An increase in salinity adds dissolved substance and results in an increase in seawater density in each layer of ocean.

Temperature: As the ocean temperature decreases, its density increases. Cold water with high salinity is some of the highest density water in the world.

Density: Due to variation in salinity and temperature, density increases with increasing salinity and density decreases with increasing temperature.