Photosynthetic biomineralization of radioactive Sr via microalgal CO sub(2) absorption

Water-soluble radiostrontium ( super(90)Sr) was efficiently removed as a carbonate form through microalgal photosynthetic process. The immobilization of soluble super(90)Sr radionuclide and production of highly-precipitable radio-strontianite ( super(90)SrCO sub(3)) biomineral are achieved by using Chlorella vulgaris, and the biologically induced mineralization drastically decreased the super(90)Sr radioactivity in water to make the highest super(90)Sr removal ever reported. The high-resolution microscopy revealed that the short-term removal of soluble super(90)Sr by C. vulgaris was attributable to the rapid and selective carbonation of super(90)Sr together with the consumption of dissolved CO sub(2) during photosynthesis. A small amount of carbonate in water could act as Sr super(2+) sinks through the particular ability of the microalga to make the carbonate mineral of Sr stabilized firmly at the surface site.