EFFECT OF SEDIMENT TYPE, TEMPERATURE AND COLLOIDS ON THE TRANSFER OF RADIONUCLIDES FROM WATER TO SEDIMENT

The effect of natural organic (O), sand (S) and clay, (C) sediments, t emperature (5, 15 and 25-degrees-C) and colloids on the transfer of Co -60, Zn-65, Cs-134 and natural U-238 from freshwater to sediments was investigated in the laboratory using lake sediment/water columns. Sedi ment type had a significant effect on the loss of these radionuclides from water. Loss of Co-60, Zn-65 and U-238 from water was generally in the order O > C > S sediment. Loss of Cs-134 from water was in the or der C > O > S sediment. Generally the loss of the radionuclides from w ater was greater at higher temperatures and was in the order Co-60 > Z n-65 > Cs-134 > U-238. The presence of colloids slowed the loss of the radionuclides from water. Transfer rates of 0.014-0.077 d-1 for Co-60 , 0.010-0.110 d-1 for Zn-65, 0.015-0.092 d-1 for Cs-134 and 0.001-0.08 4 d-1 for U-238 were measured depending on experimental conditions and were in general agreement with the range of values reported from fiel d studies.