| Abstrakt: |
The bioavailability of silicon (Si) in water systems impacts the phytoplankton productivity. There is increasing interest in Si research. Freezing of water samples is a popular preservation method, however, in the case of Si it can result in appreciable decreases in dissolved Si. Monomers and polymers of silicic acid and total dissolved Si were evaluated in artificial SiO2 water solutions during freezing and subsequent thawing in dynamics. Freezing resulted in increasing the monosilicic acid concentration in the remaining liquid phase and the formation of polymeric forms. On the 1st day of thawing, the concentrations of soluble forms of Si were significantly less than the initial values. The concentration of monosilicic acid was better recovered than that of polysilicic acids. Increasing the thawing time to 10 days increased the recovery to 77.9–93.1% for monosilicic acid, 69.1–88.0% for polysilicic acid, and 76.9–91.6% for total dissolved Si. Measuring soluble Si forms in frozen water samples collected from lake, river and creeks indicated the losses could be as high as 13% for monosilicic acid, 30% for polysilicic acid and 14% for dissolved Si. The higher the concentration of soluble Si, the greater the losses can be expected. To measure more precisely concentrations of soluble forms of Si, prolonged thawing (5–10 days) is recommended for restoration of the equilibrium between dissolved and precipitated forms of Si. [ABSTRACT FROM AUTHOR] |
Full text from SpringerLink