RADIONUCLIDE CONCENTRATIONS AND DOSE ASSESSMENT OF CISTERN WATER AND GROUNDWATER AT THE MARSHALL ISLANDS ABSTRACT A radiological 1978 to determine marine survey was conducted from September the concentrations of radionuclides environments of Ll atolls and 2 Islands, islands through November of in the terrestrial and in the Northern ¥ More than 70 cistern and groundwater samples were collected atolls; the volume of each sample was between 55 and 100 1. of 705, Marshall in fallout cistern in wet water at most deposition. atolls Except concentrations in cistern water are concentration from everywhere less wet that for Bikini The the The concentration expected and in agreement with deposition. than the predicted is at from world-wide Rongelap, 1370, the average predicted 239+ 240), concentrations fallout concentrations except at are Rongelap, Ailinginae, and Bikini where the measured and predicted concentrations are in general agreement. During the period sampled, most groundwater concentrations were everywhere higher than the concentrations in cistern water. concentrations of 206, exceeded and Ailuk Ujelang. but were lower the than levels the in cisterns cistern levels of Groundwater at Rongelap, at Utirik, 13766 Likiep, Wotho, and Concentrations of the transuranics in filtered groundwater solution were everywhere comparable to or less than the concentrations in cistern water. However, detected was a well it is difficult to assess the significance of the radionuclides in groundwater at simple hole liners did radionuclides runoff, and Therefore, in in not the other the the different the ground extend water activity be the of period may not necessarily reflect ground affected transporting concentrations On many lined with wood, above will atolls. surface. by wind, contaminated radionuclides the metal, islands, or concrete. Most Concentrations human debris detected the well traffic, into during of surface the any pit. single long-term average concentrations or the concentrations that might be observed if a lined well were extended above the surface.