PACIFIC OCEAN - Sounds like a question a 8-year old might ask and it was my grandson. He said, "Grandpa, you are on the ocean all the time, you should know." But I did not know for sure, I had ideas but no facts and promised him an answer, shortly.
I consulted numerous government articles and private laboratory studies on the Internet and several U.S. Geological Survey Publications.
One article suggested a simple experiment that you can perform in your own kitchen. Fill three glasses of water from the faucet. Drink from one and it tastes fresh even though some dissolved salts are naturally present. Add a pinch of salt to the second glass and it may taste slightly salty. But add a teaspoon of salt to the third glass and your taste buds say, "No way." The third glass of water has about the same salt content as a glass of sea water.
All water has dissolved chemicals which scientists call "salts."
An article in the U.S. Geological Survey Publication by Herbert Swenson reports, for example, when one cubic foot of sea water evaporates it yields about 2.2 pounds of salt, but one cubic foot of fresh water from Lake Michigan when evaporated, yields about one-sixth of an ounce. The sea water is 220 times saltier than the fresh lake water.
Sea water has been defined as a weak solution of almost everything. Ocean water is indeed a complex solution of mineral salts and of decaying biological matter that results from the teeming life in the seas. Most of the oceans salts were derived from processes such the breaking up of the cooled indigenous rocks of the Earth's crust by weathering and erosion, the wearing down of mountains and the dissolving action of rains and streams which transported their mineral washings to the sea. Volcanic under-sea vents also contribute to the mix.
Throughout the world, rivers carry an estimated four billion tons of dissolved salts to the ocean annually.
Past accumulations of dissolved and suspended solids in the sea do not explain completely why the ocean is salty. Salts become concentrated in the sea because the sun's heat distills or vaporizes almost pure water from the surface of the sea and leaves the salts behind.
Scientists know that at least 72 chemical elements have been identified in sea water, most in extremely small amounts. Probably all the Earth's naturally occurring elements exist in the sea.
The saltiest water occurs in the Red Sea and the Persian Gulf where rates of evaporation are very high.
Off the coast of the Columbia River the sea water is much less saline because it is mixed with fresh water of that mighty river. Sometimes river water travels far from shore before it mixes with sea water. This is shown by data gathered from a study of the Columbia River, which in an average year, carries to the ocean enough water to cover an area of 1 million acres to a depth of 197 feet. Using a radioactive tracer, scientists at Oregon State University have followed the river's water from the mouth near Astoria to a point southwest of Coos Bay, 217 miles away.
The Challenger Expedition, by the British corvette, H.M.S. Challenger in 1872 remains today the longest continuous scientific investigation of the oceans' basins. It ended almost four years later and covered 68,890 nautical miles, retrieving 77 samples from all the oceans of the world.
Two of the principal constituents of sea water are sodium at 10.7 parts per thousand and chloride at 19.3 parts per thousand. They constitute 85% of the dissolved solids in ocean water and give to the water its characteristic taste.
Mollusks (oysters, clams, and mussel), for example extract calcium from the sea to build their shells and skeletons. Crustaceans (such as crabs, shrimp, lobsters and barnacles) likewise take out large amounts of calcium salts to build their exoskeletons.
So now if my grandson gets a taste of sea water, he'll know why it tastes salty.