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The marine biogeochemistry of zinc isotopes

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dc.contributor.advisor Edward A. Boyle. en_US
dc.contributor.author John, Seth G en_US
dc.contributor.other Woods Hole Oceanographic Institution. en_US
dc.date.accessioned 2008-03-27T18:31:34Z
dc.date.available 2008-03-27T18:31:34Z
dc.date.copyright 2007 en_US
dc.date.issued 2007 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/40968
dc.description Thesis (Ph. D.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2007. en_US
dc.description Includes bibliographical references. en_US
dc.description.abstract Zinc (Zn) stable isotopes can record information about important oceanographic processes. This thesis presents data on Zn isotopes in anthropogenic materials, hydrothermal fluids and minerals, cultured marine phytoplankton, natural plankton, and seawater. By measuring Zn isotopes in a diverse array of marine samples, we hope to understand how Zn isotopes are fractionated in the oceans and how Zn isotopes may be used as tracers of marine biogeochemical processes. Common forms of anthropogenic Zn had [delta]66Zn from +0.08 %o to +0.32 %o, a range similar to Zn ores and terrigenous materials. Larger variations were discovered in hydrothermal fluids and minerals, with hydrothermal fluids ranging in 666Zn from 0.02 %o to +0.93 %o, and chimney minerals ranging from -0.09 %o to +1.17 %o. Lower-temperature vent systems had higher [delta]666Zn values, suggesting that precipitation of isotopically light Zn sulfides drives much of the Zn isotope fractionation in hydrothermal systems. In cultured diatoms, a relationship was discovered between Zn transport by either high-affinity or low-affinity uptake pathways, and the magnitude of Zn isotope fractionation. We established isotope effects of [delta]66Zn = -0.2 %o for high-affinity uptake and [delta]66Zn = -0.8 %o for low-affinity uptake. This work is the first to describe the molecular basis for biological fractionation of transition metals. Biological fractionation of Zn isotopes under natural conditions was investigated by measuring Zn isotopes in plankton collected in the Peru Upwelling Region and around the world. en_US
dc.description.abstract (cont.) Seawater dissolved Zn isotopes also reflect the chemical and biological cycling of Zn. The [delta]66Zn of deep seawater in the North Pacific and North Atlantic is about 0.5%0, and the dissolved [delta]66Zn gets lighter in the upper water column. This is unexpected based our observations of a biological preference for uptake of light Zn isotopes, and suggests that Zn transport to deep waters may occur by Zn adsorption to sinking particles rather than as primary biological Zn. The thesis, by presenting data on several important aspects of Zn isotope cycling in the oceans, lays the groundwork for further use of Zn isotopes as a marine biogeochemical tracer. en_US
dc.description.statementofresponsibility by Seth Greeley John. en_US
dc.format.extent 142 p. en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582 en_US
dc.subject Earth, Atmospheric, and Planetary Sciences. en_US
dc.subject Joint Program in Chemical Oceanography. en_US
dc.subject Woods Hole Oceanographic Institution. en_US
dc.subject.lcsh Zinc Isotopes en_US
dc.subject.lcsh Biogeochemical cycles en_US
dc.title The marine biogeochemistry of zinc isotopes en_US
dc.title.alternative Marine biogeochemistry of Zn isotopes en_US
dc.type Thesis en_US
dc.description.degree Ph.D. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences. en_US
dc.contributor.department Joint Program in Chemical Oceanography. en_US
dc.contributor.department Woods Hole Oceanographic Institution. en_US
dc.identifier.oclc 213286857 en_US


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