Matching Items (5)
Description
This paper will cover a variety of stable isotope systems, both light and heavy, that are used to interpret isotopic analysis in two different disciplines: bioarchaeology and forensic anthropology. To begin, I will give short histories of both bioarchaeology and forensic anthropology, including what is considered to be the beginning of the disciplines as well as the founders of said disciplines. Following the histories of the disciplines, there will be a short background in isotopes and isotopic analysis, including an introduction to isoscapes and how isotopic data can be collected for further interpretation. There will then be an introduction to light isotopes, focusing on the ones used for this thesis, which will lead into the background of each light isotope. Following the light isotopes is an introduction to the heavy isotopes and the backgrounds of each of the heavy isotopes. Finally, this thesis will end in the conclusions section.
ContributorsFranco, Kristina Marie (Author) / Knudson, Kelly (Thesis director) / Stojanowski, Christopher (Committee member) / School of Criminology and Criminal Justice (Contributor) / School of Human Evolution & Social Change (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
A cloud chamber allows the naked eye to observe the beta- particle track produced from certain radioactive isotopes. These cloud chambers can be used during radiation education, as they allow beta emitting isotopes to be seen. Within the apparatus, the white track that forms as a result of alcohol condensation, codenstates on the ions. These ions are left by electrons released from a radioactive isotope. In this experiment, a cloud chamber apparatus was placed under the conditions of a magnetic field. When a beta isotope is inserted into the chamber, the magnetic field should bend the beta-particle track. By measuring the radius of curvature of the electron tracks, the velocity is then observed. This velocity of the beta particle can then be used to calculate the kinetic energy, and ultimately can be utilized to identify the isotope.
The understanding of the methodology for identifying isotopes, nuclear waste cleanup can be effectively handled. In cases of environmental radioactivity, Geiger counters can only identify regions that are contaminated, as well as the number of radioactive particles per second within the region. Unfortunately they fail to determine the energy of each isotope. The identification of radioisotopes aid in the handling of cleanup and safety precautions.
This thesis focuses on the hardware and construction of the apparatus used, diving into electronics and particle physics. The software as well as future data collection and analysis will be conducted by Natjalia Bogdanovic, for defense in Spring 2020.
The understanding of the methodology for identifying isotopes, nuclear waste cleanup can be effectively handled. In cases of environmental radioactivity, Geiger counters can only identify regions that are contaminated, as well as the number of radioactive particles per second within the region. Unfortunately they fail to determine the energy of each isotope. The identification of radioisotopes aid in the handling of cleanup and safety precautions.
This thesis focuses on the hardware and construction of the apparatus used, diving into electronics and particle physics. The software as well as future data collection and analysis will be conducted by Natjalia Bogdanovic, for defense in Spring 2020.
ContributorsZand, Nicole Hanna (Author) / Tucker, Ross (Thesis director) / Lee, Robert (Committee member) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Studying natural variations in the isotopic composition of oxygen-sensitive elements in ancient marine sediments is a powerful way to study the geochemical evolution of Earth’s environments in the past. My dissertation focused on two broad aspects of isotope geochemistry: 1) the development of rhenium (Re) isotopes as a paleoredox and nuclear forensics tool, and 2) the application of mercury (Hg) isotopes as a tool to trace Hg mobility in the environment and what this movement means for isotopic changes in sedimentary rocks used to study Earth’s past. Chapter 2 is the first examination of Re isotopes in sedimentary rocks that formed ~2.5 billion years ago during a period of ocean and atmospheric oxygenation prior to the Great Oxidation Event. The data show variations in Re isotope ratios coincide with evidence for changes in oceanic and atmospheric oxygenation, supporting the use of Re isotopes as a tool to track paleoredox conditions throughout Earth's history. Another application of rhenium isotopes is explored in the third chapter on nuclear forensics. Rhenium isotopes in uranium ore concentrates (UOC) from known production locations revealed more than double the range of isotope fractionation previously reported for any natural geologic samples so far. These first Re isotope ratio data indicate that Re is a promising new tool for provenance assessment of UOCs. Chapter 4 focuses on geochemical applications of Hg isotopes. Mercury isotopes in shales are a geochemical tool that can be utilized to study the prevalence of global volcanism and detect oxygen-depleted conditions in the photic zone of ancient oceans. I measured Hg isotope ratio data from a Devonian shale bed in a road cut with varying degrees of weathering that has been well characterized for variations in elemental concentrations and other isotopic ratios. I found significant variation in mass-dependent and mass-independent Hg isotope fractionation in weathered samples. Surprisingly, however, I observed both loss and gain of Hg, when only significant loss was expected based on prior weathering studies. These findings improve the understanding of Hg mobility in nature and indicate that mass-independent fractionation can be modified after deposition in surprising ways.
ContributorsSullivan, Daniel Louis (Author) / Anbar, Ariel D (Thesis advisor) / Gordon, Gwyneth W (Committee member) / Hartnett, Hilairy E (Committee member) / Hervig, Richard L (Committee member) / Zheng, Wang (Committee member) / Arizona State University (Publisher)
Created2023
Description
All known life requires three main metabolic components to grow: an energy source, an electron source, and a carbon source. For energy, an organism can use light or chemical reactions. For electrons, an organism can use metals or organic molecules. For carbon, an organism can use organic or inorganic carbon. Life has adapted to use any mixture of the endpoints for each of the three metabolic components. Understanding how these components are incorporated in a living bacterium on Earth in modern times is relatively straight forward. This becomes much more complicated when trying to determine what metabolisms may have been used in ancient times on Earth or potential novel metabolisms that exist on other planets. One way to examine these possibilities is by creating genetically modified mutant bacteria that have novel metabolisms or proposed ancient metabolisms to study. This thesis is the beginning of a broader study to understand novel metabolisms using Heliobacteria modesticaldum. H. modesticaldum was grown under different environmental conditions to isolate the impacts of energy, electron, and carbon sources on carbon and nitrogen isotope fractionation. Additionally, the wild type and a novel mutant H. modesticaldum were compared to measure the effects of specific enzymes on carbon and nitrogen isotope fractionation. By forcing the bacterium to adapt to different conditions, variation in carbon and nitrogen content and isotopic signature are detected. Specifically, by forcing the bacterium to fix nitrogen as opposed to nitrogen incorporation, the isotopic signature of the bacterium had a noticeable change. Themutant H. modesticaldum also had a different isotopic signature than the wild type. Without the enzyme citrate synthase, H. modesticaldum had to adapt its carbon metabolic cycle, creating a measurable carbon isotope fractionation. The results described here offer new insight into the effects of metabolism on carbon and nitrogen fractionation of ancient or novel organisms.
ContributorsElms, Nicholas (Author) / Hartnett, Hilairy E (Thesis advisor) / Redding, Kevin (Committee member) / Trembath-Reichert, Elizabeth (Committee member) / Anbar, Ariel D (Committee member) / Arizona State University (Publisher)
Created2021
Description
Multi-regional assessments of the trophic niches of different baleen whale species can help elucidate patterns of interspecific and intraspecific variation and mechanisms of coexistence. Challenges in observing feeding dynamics of baleen whales make it difficult to characterize trophic dynamics on a large scale. Stable isotope analysis has been applied to studies of marine trophic ecology as a way to understand individual dietary sources of energy and nutrients as they move through a food web. Generation of Bayesian ellipses within a bi-plot space can allow us to map species trophic niches by means of their isotopic niche which may reveal underlying patterns in resource use within and between species. A detailed review of the variable differences of trophic niche width within and between different species and regions based on isotope analysis of baleen whales has not been previously published. We conducted a meta-analysis examining the isotopic niches from skin isotope data of blue, fin, and humpback whales collected in the Arctic, Atlantic, and Pacific oceans, in which we suggest patterns of niche overlap and partitioning both at the interspecific and intraspecific levels. Furthermore, we highlight variation in baleen whale plasticity to potential changes in environmental and anthropogenic stressors that may drive changes in habitat and resource use, specifically in regard to temporal and spatial variability in prey availability which can have negative consequences for baleen species in a rapidly changing environment.
ContributorsMurrell, Austin (Author) / Britton, Michael (Thesis director) / Besser, Alexi (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2024-05