It's common knowledge to learn when we're young, "don't drink ocean water, it's salty," but do you know why?
It's actually a question that wasn't figured totally out until recently, when technology and research aided in the discovery.
The first way oceans become salty is by land and rocks. The mineral content breaks away into rivers, which carry it down stream into the world oceans. This runoff is filled with ions, which some aquatic organisms use, but what is not used is left to concentrate. The two ions causing "salt water" are sodium and chloride. They combine together because one is positively charged, and the other is negatively. This combination, NaCl, is Sodium Chloride. The various concentrations of salt can help determine water temperature, location of fish, types of fish, bioavailability of oxygen, water depth, water clarity; pretty much a factor in everything. According to The United States Geological Survey, the concentration of salt in seawater, better known as, salinity, is about 35 parts per thousand.
The second way water becomes salty is where many fisherman are familiar. Fisherman around the world search for big game fish at the "canyons", which is where the second occurrence of addition of salt happens. At the bottom of mid ocean ridges an opening to the earths crust is located. These openings are called, hydrothermal vents. Unlike many scientific terms, these openings are exactly what their name states. Hydro originating from Greek meaning water, thermal defined as having to do with temperature, and vent defined as allowing something through an opening. That "something" is extremely hot mineral concentrated water from the inner depths of earths crust. This combination occurs constantly.
Credit: The United States Geological Survey. http://water.usgs.gov/edu/whyoceansalty.html
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