3. 4) Monitoring chemical and hydrologic characteristics of selected existing and newly-installed wells as is deemed necessary for construction of the most useful model of atoll hydrology. . 5) Continued evaluation of tide signals and water levels in the ocean and lagoon and on the reef to determine exterior forcing functions for island groundwater movement. 6) Incorporation of existing data and partial models into an overall model describing the hydrology, geochemistry and species residence times in the atoll environment, and ultimately predicting environmental half-lives for the various radionuclides in the different ecosystem "compartments." Visits to Bikini atoll have provided valuable data on that location and have additionally provided extremely valuable opportunities to test and validate observations or models originating in the Enewetak study. We propose to continue such participation in any Bikini atoll survey/research visits. field year; the With the trips to loss of LCU support, we anticipate that major Enewetak will be made only 2 or these will be supplemental, however, on-site technician and occasional 3 times per by the work of 1-2 man visits. Bikini trips will be undertaken when joint use of ships of opportunity is feasible. 1S. Relationship to Other Projects: This project is directly integrated with the LLL Enewetak-oriented projects (V. E. Noshkin and W. Robison, P.I.'s). The total output of the combined projects is directed toward a complete description and predictive model of the biogeochemical cycles and processes controlling radionuclide distributions and transport in the atoll environment. In addition, there hydrology aspect of this circulation study (S. V. is strong interaction between the study and the DOE-funded Smith and E. D. Stroup, lagoon P.I.'‘'s), with both projects directly concerned with tidal characteristics and The cross-reef two support ongoing transport of water and water-borne species. UH projects and the Robison LLL project currently a joint-use support for field technician at Enewetak to provide all projects between major field trips. Logistic support and scientific coordination is shared with the Mid- Pacific Marine Lab. 16. also Technical Progress in FY 1978: Because tropical storm Nadine inflicted significant damage on Enewetak during January, 1978 and forced cancellation of that period, research trips scheduled during FY 78 results are running approximately 3 months behind the anticipated schedule. It is questionable whether