24 of that of surface water under normal conditions. The tradewind and doldrum seasons bring winds primarily out of the NE and ES&, respectively. Exchange budgets for the volume of water in the lagoon have been calcuvated by Yon Arx (1254) and Noshxin et al. (1974a); these rates differ considerably. Unusual hydrological conditions have been documented by Ford (op. cit.) which could cause large variations in the water exchange budget. Yon Arx (1954) also measured coefficients of horizontal diffusion in Bikini surface waters, using dye marker experiments. Munk, Ewing and Revelle (op. cit.) estimated coefficients of vertical diffusion by using measurements of the mixing rate of oxygen-rich reef water with lagoon deep water. 3.5-2 Lagoon Sediments An extensive description of the physical, biological, and chemical aspects of the sediments of Bikini and nearby atolls has been made by r. 1. Erary, J. I. Tracey, Jr. and H. S. Ladd (1954). While some of the field stucies performed in association with these investigations occurred after initiation of nuclear testina at Bikini, there were, to this writer's knowle“-e, only minor published notes dealing with the post-Raker test sedimentary environment of Bikini. Because of this, the description of the undisturbed sec Tersary environment (as found in the 260-series USGS professional papers) corr ain most of the available background information. The reef environment at Bikini is an extremely productive and complex Sormsctty. About seven tons of organic matter/year/acre are produced as a result of photosynthetic activity by the windward reef community; of this, an eis irates 12" may be available to nourish the animal assemblage of the lagoon Terre? al., op cit. p. VI). Lagoon bottom waters are estimated to average - oat ¢ . 6 w-haer thioth the photosynthetic activi ty of the reef area (Sargent and Am Aertte 16253,