First Paragraph
Shortly after the birth of the science of analytical chemistry, over 100 years ago, the art of measuring the chemicals in the sea began with the arduous task of analyzing the six major salts in seawater—sodium, magnesium, potassium, calcium, sulfate, and chloride. It soon became apparent that these four cations and two anions make up the bulk of sea salt, and a few more, like boron, strontium, fluorine, and bromine, were all “conservative.” In other words, the salt composition of seawater was quite boring—the salts in seawater from anywhere in the world ocean contain almost exactly the same proportional composition as seawater from anywhere else—and in direct relationship to its “salinity”—a concept that originated with ocean chemists but was forfeited to ocean physicists when the chemical definition of salinity as a measure of salt mass content got corrupted and was no longer useful to calculate in situ seawater density.