In situ salinity, turbidity and temperature were measured at discrete depths and water samples for radioanalysis were simultaneously collected in the Columbia River Estuary using a specially designed instrument package. Particulate radioactivity was concentrated by filtration and the dissolved radioactivity by evaporation or ferric oxide bulk precipitation. Radioanalysis was by gamma-ray spectrometry and data reduction by computer. Chromium-51 was mostly dissolved and conservative in brackish water, while zinc-65 was mostly particulate and non-conservative. The intrusion of salt water into the estuary was seen to greatly increase the concentrations of particulate chromium-51, zinc-65 and scandium-46 near the bottom. The fall and rise in estuarine radioactivity levels were followed during an infrequent pause in Hanford reactor operations. Changes in radioactivity levels of up to three orders of magnitude were recorded at Astoria, Oregon, some 380 miles from the reactors. The pause in reactor operations enabled the determination of river flow times from the reactors to Astoria. Flow times of 12 and 19 days were measured for average river discharges of 290,000 and 130,000 c.f.s., respectively. / Graduation date: 1967

Thesis (M.S.)--Oregon State University, 1982. / Typescript (photocopy). Includes bibliographical references (leaves 37-40). Also available on the World Wide Web.

Graduation date: 1984

Thesis (Ph.D.) OGI School of Science & Engineering at OHSU, November 2007. / Includes bibliographical references.

Thesis (M.S. in environmental science)--Washington State University, August 2008. / Includes bibliographical references (p. 42-45).

Monthly samples of nutrients, phytoplankton and zooplankton were taken in the Columbia River estuary over a period of 16 months in order to determine distribution with season and salinity, and interrelationships between plankton and nutrients. Nitrate and phosphate levels in the river water entering the estuary are high in the winter and show depletion during the summer. Silicate levels are high in the river water at all seasons. Nitrate and phosphate levels are high in the entering ocean water during summer offshore upwelling. The nutrient levels in the estuary generally show a linear relationship with salinity, resulting from the levels of nutrients in the entering river and ocean water. Superimposed upon this linear relationship is a tendency for the nutrients to be enriched in the bottom waters of the central part of the estuary. The estuary phytoplankton are primarily composed of freshwater forms, and probably represent a downstream extension of the river flora. Regression analysis of phytoplankton levels vs. light, nutrients, and river flow indicates that light probably limits phytoplankton abundance on most dates. The zooplankton of the estuary are composed of three groups, preferring fresh, oligohaline, and polyhaline waters respectively. Regression analysis indicates a strong correlation between abundance of the freshwater group and river temperature. The factors controlling the abundance of the oligohaline and polyhaline groups are less obvious. The oligohaline group, principally Eurytemora affinis, reaches the greatest population density (100,000/m³ or more). Regression analysis indicates a close correlation between Eurytemora abundance and phosphate levels. This indicates a strong potential for zooplankton regeneration of phosphate necessary for phytoplankton growth. / Graduation date: 1970

Graduation date: 1983

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [111]-116).

Thesis (M.S.)--Oregon State University, 1993. / Typescript (photocopy). Includes bibliographical references (leaves 85-87). Also available on the World Wide Web.

Thesis (M.Oc.E.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 51-54). Also available on the World Wide Web.