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The world's oceans or seas are vast water bodies that comprise an estimated 96.5% of Earth's water reserves.
Oceans are enormous bodies of saltwater that cover about 71% of the Earth. They break into five primary ocean basins forming approximately 321 million cubic mi (1337 million cubic km) of ocean water.
The term ocean is associated with the Earth's oceans, like the Atlantic Ocean, Pacific Ocean, Indian Ocean, Southern or Antarctic Ocean, and Arctic Ocean. It is interesting to know that the oceans and seas on Earth are not the only water bodies with salt water. All water bodies on the planet are considered to have minute salt levels.
You might want to learn more about other fun facts on topics related to oceans. Look at our other articles, like - why oceanic plates go under continental plates and facts about basking in the sun.
Ocean water is commonly filled with potassium, sodium, and chloride minerals. However, our oceans are not uniformly salty, and their salinity depends on the area. As stated by the Scripps Institution of Oceanography, the oceans of the world contain about 110 quintillion lb (50 quintillion kg) of salt. All the minerals from rivers and the sea are carried into the oceans, leading to a high salt concentration. The salt content is assumed to remain primarily static since the water cycle only leads to the evaporation of water vapor, while the dissolved salt remains in the sea.
Thus, all ocean waters are salty. The Pacific Ocean, located between Asia and Australia, is the largest of its kind, while the Atlantic Ocean has the highest salinity level. The areas around the Atlantic Ocean are dry areas filled with rocks that experience excess erosion, making the ocean denser and salty.
Smaller bodies of water, such as seas and rivers, also carry minerals from eroded rocks as they flow, even though the salt concentration in these water sources is not very high. Later, when this water is carried into oceans, it adds to the saltwater composition, like in the Mediterranean Sea and the Red Sea. The smaller bodies of water are salty because of this.
In the present day, all oceans of the Earth have variable quantities of dissolved salts. However, researchers do believe that during their initial formation about 3.8 billion years ago, the oceans used to be bodies of fresh water. Mineral salts have since been deposited into the oceans by rivers and from other natural processes. Thus, there are no existing freshwater oceans. Some freshwater lakes are Lake Superior, Lake Michigan, and other local lakes. However, these small water bodies are also salty to some extent.
A vast aquifer of fresh water has been found near the coastline of New Jersey up to Massachusetts. The freshwater body sits below the Atlantic Ocean and contains about 739 trillion gals of water. This is only one of the many freshwater aquifers that can be found in the world.
The presence of salt in seawater and oceans results from erosion, and the process begins when it starts to rain. Rainfall on land constitutes freshwater that is eventually deposited in rivers, lakes, and streams. These rivers and lake outlets wash the soil and erode rocks in their path, and deposit mineral salts into the oceans. As seawater and ocean water evaporates under the sun, clean water vapor condenses into rain, providing fresh water to rivers and lakes, while the oceans retain all the deposited salt. This process has continued over billions of years, adding more salt into the oceans. About four billion tons of dissolved salts are deposited into seas and oceans by rivers annually. Mineral salts can flow back into the ocean from hydrothermal vents that form on the oceanic crust.
The significant oceans all over the Earth are the Atlantic Ocean, Pacific Ocean, Indian Ocean, Antarctic, and Arctic Oceans. All oceans on Earth are salty water bodies containing different types and quantities of salts. It is estimated that the salinity levels of oceans range from around 34 ppt - 36 ppt (parts per thousand). The Antarctic and Arctic oceans have the lowest salinity levels, measured to be 34 ppt and 30 ppt, respectively. The low salinity level is due to the floating ice and icebergs in these oceans that add fresh water and reduce the salt composition in a gradual process. However, it is necessary to note that these are not constant measurements. The salinity levels of oceans or other water bodies will vary at different locations, due to time and various natural events.
Here at Kidadl, we have carefully created many interesting family-friendly facts for everyone to enjoy! If you liked our suggestions that all oceans are salt water, why not look at Hurricane Katrina facts, or How is Sea Glass made?
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