ee Health Physics Pergamon Press 1965. Vol. 11, pp. 1445-1457. Printed in Northern Ireland cal Labora. \ (1964), 404/64, p. . Larson, iby v, peecinhold, PRELIMINARY STUDIES OF THE PERSISTENCE OF TRITIUM | AND “CIN THE PACIFIC PROVING GROUND* JOHN J. KORANDA Bio-Medical Division, Lawrence Radiation Laboratory, University of California, Livermore, California / 14, 27) Soil Py, O Expert (Presented by J. J. KoRANDA) nization, Abstract—Theresults of a preliminary survey of detonation environments in the Pacific » Suppl, Proving Grounds indicate that residual tritium and 4C are present in relatively high concentrations in soil materials of the detonation sites at times up to 12 years after the event. Exchange of soil-boundtritium with the available soil water takes place at a slow butsignificant rate and tritium is detectable in plants growing in the detonation environments. MC isalso elevated in the terrestrial plants. The basis for the elevated 14C is not implicit in these preliminary data. Tritium and )4C are also present in elevated concentrations in marine organisms. However, due to the high rate of exchange of the lagoon waters with the open sea, these elevated concentrations are highly localized in the vicinity of the detonation site (Mike Crater). INTRODUCTION Tue FATE of residual radioactivity from nuclear detonations in natural environments has been studied with increasing intensity since the beginning oftesting in the S.W. Pacific in 1946. Much of the biological information on the local effects of residual radioactivity is about either the atoll environments of the Pacific Proving Grounds in the Marshall Islands or the desert areas of the Nevada Test Site. Much ofthis information pertains to fission products and their movementin soils, plants and animals of the detonation environment although some recent research has been concerned with induced radioactivities. With the advent of thermonuclear devices and the subsequent lowering of the fission—fusion ratios, induced radioactivities have grown in importancerelative to fission products. Tritium and "C represent a significant portion of the tsidual radioactivity from a thermonuclear detonation. Hydrogen and carbon are ubiquitous elements in the biosphere and are included inevery significant biological molecule. Tritium and 4C, therefore, will be incorporated into the * This work performed under the auspices of the U.S. Atomic Energy Commission. 8 on . basic structures of organisms in the detonation environment. While tritium and “C have been detected and studied in worldwide fallout, the fate of these two radioelements in local detonation environments and in the biosphere in general has received little attention. Recent evidence from the Sedan cratering detonation in southern Nevadaindicates that tritium is present in high concentration in the geological materials displaced and modified by the detonation 2 years after the detonation. Therefore, a study was initiated to investigate the persistence of tritium and C in detonation environments. This paper presents the results of a preliminary survey for tritium and C in an atoll environmentof the Pacific Proving Grounds. Detonations occurred from 6 to 12 years ago in the sites sampled, and tropical vegetation has reinvaded most of the areas affected. Tritium and C activity was determined in plants, animals and soils from a variety of habitats. The effects of indigenous substratum, climatology, and uptake by the biota on the persistence of tritium and “C are discussed. Evidence indicates that both tritium and “C have been retained by the physical materials in the detonation environment in relatively high 1445