THE REACTIVITY OF DISSOLVED SILICON IN SOME NATURAL WATERS

Abstract

Several samples of natural waters, from the deep North Atlantic Ocean and four rivers in southern England, have been examined for the presence of dissolved silicon unreactive under the conditions generally used for its absorptiometric determination; none was detected. Polymeric silicon added to the samples depolymerized completely within a few days, most rapidly in seawater. When filtered river water was frozen and subsequently thawed, the silicon was largely present in an unreactive form; the unreactive fraction could be removed by membrane filtration. The silicon became entirely reactive on standing at about 25C for several hours. Unreactive forms of dissolved silicon were not formed when natural waters of salinity >27‰ were similarly treated.