In this chapter, aspects concerning the complexity of marine chemistry were
discussed. In this scope, important reactions of metals and non-metals with inorganic
and organic constituents of water and sediments were considered. In addition to these
reactions, this chapter considers biokinetic aspects, which are responsible for very
important regulations concerning the assimilation and biotransformation of many
chemical elements. Finally, two major environmental problems (eutrophication due to
the excessive supply of nitrogen and phosphorus, and release of organotin compounds
and copper from antifouling paints used on ships’ hulls) were presented with the
intention of discussing some forms in which uncontrolled introductions of metals and
non-metals can change negatively the quality of marine ecosystems.
Keywords: Bioaccumulation, Essentiality, pE X pH Diagrams, Toxicity.