Several excellent and thoughtful reviews on the chemical composition of seawater were published in the early 1980s. In particular, Bruland discussed speciation of various elements, Broecker and Peng [ 1982] focused on the dynamic aspects, and Quinby-Hunt and Turekian  presented a way to predict oceanic concentrations. Since then, however, new data continuously became available based on the advanced methods of sampling and analysis, making it clear that the concentration levels and oceanic distributions of many trace metals had to be revised. Needless to say, it is difficult to determine extremely low levels of trace chemical constituents, and none of the laboratories can determine all of the elements in seawater. Thus, we are not yet capable of obtaining every data set from the same location, even through intensive collaboration.