Differences in the dissolved chemistry of lakes devastated by the 18 May 1980 eruption of Mount St. Helens are attributable to location relative to the lateral blast trajectory of the eruption and to the emplacement of mineral deposits. Elemental enrichment ratios of pre- and posteruption measurements for Spirit Lake and comparisons of the chemical concentrations and elemental ratios for lakes inside and outside the blast zone reflect the influences of the dissolution of magmatic and lithic deposits. The pH changes were minor because of buffering by carbonic acid and reactions involving mineral alteration, dissolved organics, and biological processes.

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Since 1946, personnel from the School of Fisheries, University of Washington (Applied Fisheries Laboratory, 1943-1958; Laboratory of Radiation Biology, 1958-1967; and Laboratory of Radiation Ecology, since 1967), have studied the effects of nuclear detonations and the ensuing radioactivity on the marine and terrestrial environments throughout the Central Pacific. A collection of reports and publications about these activities plus a collection of several thousand samples from these periods are kept at the School of Fisheries. General findings from the surveys show that (1) fission products were prevalent in organisms of the terrestrial environment whereas activation products were prevalent in marine organisms; (2) the best biological indicators of fallout radionuclides by environments were (a) terrestrial-coconuts, land crabs; (b) reef-algae, invertebrates; and (c) marine-plankton, fish. Studies of plutonium and americium in Bikini Atoll showed that during 1971-1977 the highest concentrations of 241Am, 2.85 Bq g(-1) (77 pCi g(-1)) and 239,240Pu, 4.44 Bq g(-1) (120 pCi g(-1)), in surface sediments were found in the northwest part of the lagoon. The concentrations in the bomb craters were substantially lower than these values. Concentrations of soluble and particulate plutonium and americium in surface and deep water samples showed distributions similar to the sediment samples. That is, the highest concentration of these radionuclides in the water column were at locations with highest sediment concentration. Continuous circulation of water in the lagoon and exchange of water with open ocean resulted in removal of 111 G Bq y(-1) (3 Ci y(-1)) 241Am and 222 G Bq y(-1) (6 Ci y(-1)) 239,240Pu into the North Equatorial Current. A summary of the surveys, findings, and the historical role of the Laboratory in radioecological studies of the Marshall Islands are presented.

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