A sea weed （Scirpus grossus Linn ） was taken as an experimental plant to indicate radioactive pollution in estuaries. The results showed that the accumulation of 137Cs

65Zn

60Co

50Fe and 54Mn hy Scirpus grossus was proportional to their concentration in the soil. After the nuclidcs in the soil were washed out for one month

more than 9. 2% of the nuclides in Sctrpus grossus still remained

within the detection limit . Absorption of the nuclides from water by the stem above soil was larger than that from soil by the root. The concentration factors of the root . the stem underneath soil and stem above soil for the nuclides were determined. Radioactive pollution degrees of both the sea water and the soil can be deduced by means of conversion of the concentration factor’s formula.