STUDIES ON THE UTILIZATION OF AQUATIC PLANTS FOR REMOVING RADIOACTIVE MATERIALS FROM WATER BODY(Ⅲ)THE ACCUMULATION AND RELEASE OF Sr90,Y91,Cs137 AND Ce144 BY AQUATIC PLANTS AND THE EFFECT OF Ca ON THE ACCUMULATION OF Sr90

Spirogyra sp., Hydrodictyon reticulatum (L.) Lager, Spirodela polyrhiza (L.)Schleid., Ceratophyllum demersum L., and Eichhornia crassipes Sohms, all have certainability of absorbing and accumulating Sr90, Y91, Cs137 and Ce144. The coefficient of accumulation and percentage of clearance are negatively relatedwith the concentration of the stable calcium in the water, but positively with theduration of the experiment. The same species of aquatic plant have different coefficients of accumulation fordifferent kinds of radioactive materials. For instance, on the eighth days, the coefficientof accumulation by Ceratophyllum demersum was: Ce144-1500. Sr90-1220, Y91-480,Cs137-160. Different species of aquatic plants have different abiiity to absorb andaccumulate the same kind of radioactive material. Thus, the coefficient of accumula-tion of Sr90 on the eighth days was: Spirodcta polyrhiza-1380, Ceratophyllum demer-sum-1220, Spirogyra sp. -820, Hydrodictyon reticulatum-460, Eichhornia crassi-pes-380. Inasmuch its aquatic plants can accumulate radioactive materials, the use ofaquatic plants to purify the water polluted by Sr90, Y91, Cs137, Ce144, etc. has itssignificance not only in theory but also in practice.