Uranium radionuclides and organic biomarkers in sediment core RC27-42

Uranium series radionuclides and organic biomarkers, which represent major groups of planktonic organisms, were measured in western Arabian Sea sediments that span the past 28 ka. Variability in the past strength of the southwest and northeast monsoons and its influence on primary productivity, sea surface temperature (SST), and planktonic community structure were investigated. The average alkenone-derived SST for the last glacial period was ~3°C lower than that measured for the Holocene. Prior to the deglacial, the lowest SSTs coincide with the highest measured fluxes of organic biomarkers, which represent primarily a planktonic suite of diatoms, coccolithophorids, dinoflagellates, and zooplankton. We propose that intensification of winter northeast monsoon winds during the last glacial period resulted in deep convective mixing, cold SSTs and enhanced primary productivity. In contrast, postdeglacial (<17 ka) SSTs are warmer during times in which biomarker fluxes are high. Associated with this transition is a planktonic community structure change, in which the ratio of the average cumulative flux of diatom biomarkers to the cumulative flux of coccolithophorid biomarkers is twice as high during the deglacial and Holocene than the average ratio during the last glacial period. We suggest that this temporal transition represents a shift from a winter northeast monsoon-dominated (pre-17 ka) to a summer southwest monsoon-dominated (post-17 ka) wind system.

Uranium fuel cycle radiation protection requirements : environmental impact statement.

F available only in microfiche.

Proposed standard for radon-222 emissions from licensed uranium mill tailings : draft economic analysis /

"40 CFR Part 61, national emission standards for hazardous air pollutants."

Allocation of uranium enrichment services to fuel foreign and domestic nuclear reactors, Energy Research and Development Administration, Department of State : report to the Committee on Foreign Affairs, House of Representatives /

Publication date stamped on cover.

Solvent extraction of uranium : a literature search /

"March 1957."

Extrusion of uranium, uranium alloys, and uranium compacts : a literature search /

This literature search consisting of 240 references to unclassified reports and published literature has been taken from Nuclear Science Abstracts, the official abstract journal of the United States Atomic Energy Commission. The period covered is January 1951 through May 31, 1961. Abstracts for the references can be found by use of the NSA abstract numbers provided.

An analysis of competitive structure in the uranium supply industry : staff report to the Federal Trade Commission /

Bibliographical footnotes.

Reactions of uranium oxides and liquid nitrogen tetroxide /

Work performed at the Argonne National Laboratory.

The powder metallurgy of uranium /

Uranium is a ductile metal and cannot be comminuted to a fine powder by any mechanical means such as crushing, milling or grinding. Uranium, however, reacts readily with hydrogen and forms UH3, which is a fine powder of less than 400 mesh screen size. The factors controlling the rats of the hydride formation are: (a) The surface area of the metal; (b) the temperature at which the reaction takes place; (c) the pressure of hydrogen. In order to increase the reaction area, one has to hydride small metal pieces rather than a single mass. The hydrogen reacts with uranium metal at temperatures as low as 100 deg to 1500 deg, and the reaction rate becomes quite rapid at approximately 225 deg C. The hydrogen for this purpose has to be of high purity and any small amount of oxygen in hydrogen delays the start of the reaction.

Exchange reactions of uranium ions in solution /

Work performed at the Argonne National Laboratory.