Additives and Trace Elements
Before considering each element's role it is necessary to understand what is present in saltwater. Saltwater contains virtually all known elements. Those that are found in high concentrations - at least 1 part per million ( ppm) - are called major elements . This list includes sodium, magnesium, calcium, strontium, potassium, chlorine, sulfur, bromine, fluorine, carbonate, and boron. At a salinity of 35 pars per thousand (ppt) , there are about 35g of major elements in a kilogram of saltwater. The other elements that are present in seawater are found in very insignificant amounts and make up approximately 0.1% of the total dissolved solids. These elements have come to be known as trace elements and while they are only present in tiny amounts, they have still been found to be critical for the successful maintenance of life. These important trace elements include phosphorus, nitrogen, molybdenum, lithium, cobalt, silicon, iodine, iron, vanadium, copper and barium. Some of these trace elements, such as phosphorus and nitrogen, are crucial for the completion of biochemical processes. Others are important in that they are extremely toxic if they reach higher than desired levels.