DISTRIBUTION OF TRANSURANIC NUCLIDES IN SOILS: A REVIEW E. H. Essington and E. B. Fowler Los Alamos Scientific Laboratory Los Alamos, New Mexico ABSTRACT The literature is reviewed to ascertain the degree of movement and the distribution patterns for transuranic and uranium nuclides in soils. Typical plutonium and uranium profiles are presented and an attempt is made to identify unique characteristics causing deviation from an ideal distribution pattern. By far most of the distribution observations are with plutonium and little is reported for uranium and other transuranic nuclides. INTRODUCTION In the past decade interest has been growing in the environmental im- pact of certain transuranic radioisotopes because of their potentially hazardous nature to man. The potential for dispersion of these transuranics due to accidental release from components of the nuclear fuel cycle, improper radioactive waste management, accidental or purposeful nuclear weapon incidents, and further redistribution of existing global fallout and specific loci of contamination is being studied. There has been specific emphasis, during the past few years, on determining the degree of vertical migration of certain transuranic radioisotopes in soils, both in the laboratory and under field conditions. Further investigation on the environmental fate of transuranic elements is urgently needed in order to assess their long term distribution patterns. This paper reviews past documentation on the vertical distribution of transuranic nuclides and uranium in the terrestrial environment under natural or near natural conditions. Observations made thus far will aid in predicting future redistribution rates and indicating where additional evaluations are needed. 41