-555- Plutonium and 9°Sr Data Base. McClellen Laboratory completed the 30Sr and plutonium analysis of the Enewetak Atoll! soll samples. However, before they could begin to analyze the vegetation samples, thelr "mission work'' was Increased and they had to terminate their support of our project. As a result, we have not been able to develop our data base on concentration and correlation factors for the two radionuclides. Currently, we are trying to coordinate and establish wet chemistry analytical support with other organizations to complete the analysts and evaluate the uptake and potential doses for atl major radionuclides found at the atolls. Effect of Fertilizer on '37Cs Uptake. We have initially evaluated the impact of fertilizer on the uptake of 437cs tnto the Jeaves and fronds of pandanus and coconut. Preliminary data show the average uptake tn coconut fronds to be 67 pCi/g + 75% for hot soll without fertilizer and 22 pCi/g + 50% for hot soll with fertilizer. These early results are significant and indicate that a fertilizer program may indeed reduce the uptake of 137¢s. available for 9°SR and plutonium. No data are yet Radionuclide Residence Time. We have continued our sampling of _ coconut and pandanus trees on other islands at Enewetak Atoll to evaluate the residence time of radionuclides In the atol! environment. The data for !13’¢s appear to Indicate a residence time significantly less than 30 y, but seasonal fluctuations need to be determined in order to make an exact interpretation. Engebi Istand Studies. Our studies on Engebi Island have been directed toward determining the cycling mechanisms of radionuctides in the atoll environment. We have collected nearly 2 y of data from several tocations on the island, including radionuctide concentrations in various compartments, canopy growth, rate of litter productton and litter decay, leaching of radionuctides from each compartment, and radionucltde residence times. gies dic However, in August, 1977, without consulting any of the ongoing programs, the military and DOE teams bulldozed and completely denuded Engebi Island of all vegetation other than our test plots. All of the long-term follow-up sites were destroyed. Now we can only sainple the vegetation which reestablishes itself to see If the clearing procedure produced any major changes in the radionuclide concentr=tions and evaluate the potential of the new trees as part of our long-term cycling and residence time studies. Comparison of Radionuclide Resuspension on Engebi and Bikini Islands. The clearing of Engebi Island does offer the opportunity to evaluate and compare the resuspension process on this denuded island with Bikini Island which Is well vegetated. Such clearing will occur on many islands as housing Is built and subsistence and cash crops are Planted. We belleve that a siqnificant Increase In radionuclide resuspension may be seen for the first several years after the [siand is cleared. Depending on the avallabitity of support for Marshall