Rate of dissolution of diatom silica walls in seawater

The solubility and dissolution rate of silica were investigated using cell walls prepared from two species of diatoms, Thalassiosira decipiens and Rhizosolenia hebetata forma semispina. The solubility (C _e) as a function of temperature (T, °C) can be described by the following equation: C _e (SiO₂ mg l^-1)=67.8+1.48 T. The first-order reaction equation without the surface-area term was considered to be reasonable in estimating the dissolution rate of biogenic silica in the ocean system. The rate of dissolution differed not only from one species to another but also from one portion to another portion of the same wall. The rate constants of dissolution in the ocean system were estimated to range in the order of from 10^-1 to 10^-9 per hour.