What makes the ocean salty?

Over 30 elements, ions and compounds can be found dissolved in seawater. Six of these (chlorides, sulfates, sodium, magnesium, calcium and potassium) comprise 99% of the total. The presence of these dissolved elements, ions and compounds makes the ocean "salty." Salinity refers to the amount of these dissolved elements, ions and compounds present in water. Average salinity in the ocean is 35 parts per thousand. This means that for every 1000 grams of seawater 35 of those grams are composed of "salt." The ratio of these compounds and elements to each other is consistent throughout the ocean regardless of salinity.

Scientists believe that ocean salinity has remained the same for the last 1.5 billion years. The elements, ions and compounds in the ocean that we refer to as "salt" are derived from the chemical and physical breakdown of rock material on the continent. As rocks erode, elements, ions and compounds wash into streams and rivers eventually washing into the ocean. As the rock material continues to break down, salts are continually added to the oceans. However salts are continually removed from the ocean keeping salinity constant. Salts in the ocean are removed in the sea spray that splashes out of the oceans, salts become locked in sediments that are deposited on the ocean floor and salts are removed from water through biological activity.

The salinity in the Chesapeake Bay ranges from fresh water at the head of the Bay to 30 parts per thousand at the mouth of the Bay in Virginia Beach. Salinity is greater in the bottom layers of the Bay and fresher in the surface layers. The overall average salinity of the Chesapeake Bay is between 13 and 17 parts per thousand.