Seawater element contents salinity

Because of their role as an elemental sink, the formation and weathering of evaporites has the potential to affect the salinity of seawater. This can in turn alter climate, because the heat capacity of seawater is a function of its salt content. Changes in the salt content of seawater also have the potential to affect survival of marine biota, particularly the calcifiers. 

The maximum rate of change in sensitivity for each element takes place at salinities near those of fresh waters therefore, such samples should always be analyzed by standard additions. This is also necessary because of the variability of major ion compositions of natural fresh water, which may be expected to affect sensitivity, along with changes in the total salt content. Fortunately, small changes of salt content near the values of salinity found in the open sea have very little effect on the analytical sensitivity for any of the metals studied. Trace metal analysis of seawater may, therefore, be performed using standard additions on selected samples only. 

About 97% of Earth s water is in the oceans. This saline water contains vast amounts of dissolved minerals. More than 70 elements have been detected in the mineral content of seawater. Only four of these—chlorine, sodium, magnesium, and bromine—are now commercially obtained from the sea. The world s fresh water comprises the other 3%, of which about two-thirds is locked up in polar ice caps and glaciers. The remaining fresh water is found in groundwater, lakes, rivers, and the atmosphere. 

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