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The structure and chemistry of polar glacier ice.

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Call No.	GB2595 .C85 2002
Author	Cullen, Daniel C.
Title	The structure and chemistry of polar glacier ice.
Date	2002
Abstract	This dissertation explores the spatial and temporal distributions of impurities in natural ice. Using polarized light, ion chromatography (IC), synchrotron x-ray topography (SXT), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDS), ice obtained from cores drilled through thousands of meters of glacial ice at the Greenland summit, Byrd Station, Antarctica, and Lake Vostok, Antarctica is characterized in terms of defect structure, impurity concentration, location, and morphology. Comparisons between natural ice and laboratory-grown ice, as well as between the different natural ice cores, are also explored. The information garnered is relevant to the study of the earth''s paleoclimate, knowledge of which is used to ascertain the accuracy of current climate models, and the modeling of glacier rheology, where even very small amounts of certain elements can greatly effect the deformation of ice. Additionally, the study of impurities in Lake Vostok accretion ice bears on an ongoing discussion regarding the possibility of viable life in this subglacial lake. A new method is presented for determining the microstructural location of impurities in polycrystalline ice, which involves allowing the ice to sublimate under vacuum and then identifying the concentrated impurities using energy-dispersive microanalysis, is presented. The method tests for the presence of impurities in both the grain boundaries, and for the first time, the lattices of natural polycrystalline ice. Using this technique, filaments consisting chiefly of NaCl (Greenland), and Mg-S (Byrd Station), were observed in the grain boundaries of the ice. In one Lake Vostok accretion ice triple junction (3-grain intersection), unusual crystalline features consisting predominantly of Mg, S, and O were discovered. Significant concentrations of impurities (chiefly S, Cl, Na, Mg) were shown to exist in all of the natural ice lattices studied, thereby casting doubt on the pervasive belief that impurities in natural ice predominantly reside in triple junctions.
Description	1 online resource (xxiv, 313 leaves) : illustrations (some color)
Format	application/pdf
Advisor	Baker, Ian
Subject	Ice -- Analysis -- Polar regions. ; Glaciers -- Polar regions.
College	Thayer School of Engineering.
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D)--Dartmouth College.
Copyright	In Copyright. This material is protected by copyright and/or related rights. You are free to use this material in any way that is permitted by copyright law that applies to your use. For other uses, you need to obtain permission from the rights-holder(s). http://rightsstatements.org/page/InC/1.0/
DOI	https://doi.org/10.1349/ddlp.2696

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The structure and chemistry of polar glacier ice.

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The structure and chemistry of polar glacier ice.

The structure and chemistry of polar glacier ice.