Boron Regulation in the Oceans

Abstract

IN the search for a general theory to explain the chemical composition of ocean water, emphasis has been put on inorganic equilibrium models which are themselves based on the postulate of a steady state oceanic system^1–3. The major cation content and _pH of ocean water at present are very similar to the values predicted by equilibrium calculations, and one of the most important of these reactions is supposed to be that of the amorphous aluminium silicate fraction of river sediment with dissolved bicarbonate, silica and cations in ocean water to form authigenic sedimentary silicate minerals. Mackenzie and Garrels³ suggest that these reactions take place before deposition of the sediments and calculate that only 7 percent of the amount of suspended river sediment entering the ocean would have to form authigenic minerals if the composition of the oceans were to remain constant. Although there is no conclusive field evidence for the proposed mineral–water reactions and their effect on the major cation budgets in the oceanic system, there is field and laboratory evidence to show that boron is taken up by the fine-grained silicate material during the transfer from the fresh water to the marine environments^4–10.