ad Po ct 14 xO ~ 4 QO ory Oo m7 yO rs om 02 g effective concentration factors should be base soil water concen of radionuclides rather than on the total soil concentraticns. of H Os HS Oo wD OH ts Oo Mm ‘ } i Go 2 j ey @m fa 9 © atoll ecosystem can be controlled by from the decay of litter dropred from the & v ow OY tp BES oc?"099 Q 1972 survey but which have considerable significance in the ulvinet lens wat from the Preliminery data men as he reinhebits the atoll. at Enewetak Atoll indicate that recycling and turnover oe redionucl S am Ps © Ca G ht ' ¢ recognized by our marine group and emphasized in their researcen progr The recent research on marine and lens water at Enewetak Atoll reve important aspects of the terrestrial ecolcgy that were not evicen~ xs‘ 7 Cys fitf ‘ nn m The importance of the recycling and turnover times of radionuclide § on in Scil, Soil Water, ans Encus 4 Distributicn of Radionuclides te 2, Further research is required (1) to clserify the role of groundwater in controlling the disappearance of radionuclides in the Atoll, (2) to determine D + ct tes m9 Oo ct °o a 2 QD j- }- ny i 9 the actual contentratic rc) Ye the actual cycling process involved in order to evaluate potenviel metiods of blocking nuclide untske in plant species in the food chain, ( groundwater concentrsts concentration Pactors concentration in soil ot zone with the concent water, to nely describe the time-cerendence of radionuclides groundwater /lenis-water system. Therefore, soil cores will be obt northern islends (e.s5. Janet, Belle) in and around the plantins cores Will be analyzed by leaching the coil with reasents acp water solutions to determine tne rracvien cf soil redionuclic available to tne plants. Also, the humic fracticn cf the soi from tne carbonate matrix to determine which portion contains Sr. : If the humic fraction end soil water comsein the redicectivity and thus constitute the source of available radionuclides for the slants, then concentrsiicn factors can be cetermnined Tor the various Tood ond indicator vtlants Tor Cs, Sr, and Pu. Concentration factors determined previously frcem soil neve varied over @& wide range perhaps because the total soil concentretion is net the critical factor. Therefore, predictive evaluations could b e easmore reliable by developing concentration factors based upon soil water rether then upon soil. There is some question whether the plants of the Atoll are really shallow, surface-rooted or whether they may actuslly use lens water for growtn the lens is of very low saline content. where Lysimeters will be installed in soil pits to collect soil-water through-flow to determine the radicnuclide concent profile as water moves downwerd toward tne lens. The concentretions of radionuclides will be compared with those in soil water extracted from the surface horizons of the soil. When u rece Gata are evailable, concentration factors can be calculated for sr, 1 31¢s and Pu, to provide acditional estinates of the rate of input of radionuclides into the len water from the soil column.