Marine mammals breeding in sympatry use resources differently depending on their time-activity budgets and prey distribution. We measured isotopic values and patterns of δ15N and δ13C in keratinous whiskers of satellite-tagged adult female Antarctic (Arctocephalus gazella) - and Subantarctic (Arctocephalus tropicalis) fur seals from three colonies at Marion Island in the Southern Indian Ocean. The three sympatric colonies were Mixed Pickle (HD_MP), Rockhopper Bay (LD_RhB), and Watertunnel (HD_WT). A comparison between two colonies of differing A. tropicalis densities will also be investigated. We investigated resource use in breeding mature females over varying time and spatial scales during summer and winter. The aim was to understand the variation in resource and habitat use at population and individual levels. The whiskers of A. gazella and A. tropicalis grow constantly at a rate of 0.16 ± 0.05 day-1 and 0.12 ± 0.05 day-1, respectively. To compare and relate behaviours, the stable isotope data and satellite tracks were grouped into winter and summer (pooled for 2010 - 2014). In summer, A. gazella from HD_WT had a larger isotopic niche width (0.85 ± 0.67‰2) compared to A. tropicalis from both HD_MP (0.18 ± 0.19‰2) and LD_RhB (0.21 ± 0.15‰2). However, the isotopic niche width of A. gazella reduced in size by more than half (0.40 ± 0.40‰2) during winter when the mature females were no longer constrained by the lactation mandate. The mean δ15N values in whiskers of both A. tropicalis and A. gazella in summer were similar (11.3 ± 0.4‰ and 11.0 ± 0.9‰, respectively). The A. gazella broadens its’ isotopic niche feeding at different trophic levels in summer (lactation period). We used a Repeatability index (R) to assess levels of intra- and inter-individual consistency. Repeatability indicated that the bigger isotopic niche width for A. gazella is attributed to high inter- and intra-individual variability in their resource use. The A. gazella individuals ranging closer to the colony consistently consumed myctophid fish. Other individuals foraged on low 15N content euphausiids (i.e., Euphausia spp. and Thysanoessa spp.) south of Marion Island in both winter and summer. The A. tropicalis from LD_RhB were repeatable in their δ15N values (trophic level) (Rglobal = 0.63; [95% CI: 0.29 – 0.80]) and δ13C values (habitat) (Rglobal = 0.69; [95% CI: 0.35 – 0.84]). At HD_MP, the A. tropicalis colony, diet was moderately repeatable (Rglobal = 0.33; [95% CI: 0.11 – 0.51]) while habitat was repeatable (Rglobal = 0.58; [95% CI: 0.33 – 0.73]). Consistency in diet (Rglobal = 0.27; [95% CI: 0.08 – 0.44] and foraging habitat (Rglobal = 0.45; [95% CI: 0.21 – 0.63] was moderate at HD_WT, the A. gazella colony. The diet varied with habitat at the individual level, across seasons. Segregation in diet and foraging habitat minimises resource-use overlap between sympatric fur seals. The behaviour of A. gazella from HD_WT (a high-density colony) might have a direct or indirect impact on the A. tropicalis from LD_RhB (a low-density colony) (i.e., competitive exclusion). Seasonality, at-sea movement, and intrinsic factors shaped the foraging behaviour and diet of adult female fur seals breeding at Marion Island. Some breeding mature females changed diets between seasons and depending on foraging habitat. / Dissertation (MSc (Zoology))--University of Pretoria, 2021. / NRF, Grantholder linked / Zoology and Entomology / MSc (Zoology) / Unrestricted

In order to achieve a more accurate input value for groundwater age determining models, δ13CVPDB values for soil gas were evaluated at 50 cm depths in locations throughout Utah in order to define correlations between δ13C and environmental parameters. 16 sites were chosen that exploited large changes in elevation and latitude which provided variations in climate, precipitation, plant community, etc. Gas samples were collected over 1-1½ years, and soil samples were collected at depth during installations. Field and laboratory studies were also used to evaluate CO2 and δ13C change with depth. It was discovered that in mountainous recharge areas, the mean δ13C value was −21.8 ± 2.8‰ (2σ). Use of this value reduced the uncertainty in groundwater age models by close to half relative to the current assumed range of -13‰ to -28‰. One arid and one semi-arid site were located at Pilot Valley (mean -11.0‰ ± 2.0, 2σ) and the mouth of Cedar Canyon (mean -17.5‰ ± 0.8, 2σ). The high values at these locations may be due to low root respiration and low microbial activity rates caused by high temperatures, low precipitation, and low vegetation density. Correlations among environmental parameters and δ13C values were discovered with ANOVA, but the differences were small enough that for practical purposes they are insignificant.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20750号 / 理博第4326号 / 新制||理||1622(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 伊藤 正一, 教授 生方 貴男, 教授 田上 高広 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy, School of Physics. Johannesburg, 2017. / Accelerator Mass Spectrometry (AMS) is an ultra-sensitive isotopic analysis technique that allows for the determination of isotopic ratios of rare long-lived radionuclides such as radiocarbon. AMS has become an important tool in many scientific disciplines, due to its sensitivity of detecting isotopic ratios at the level of 10-15 by making use of nuclear physics techniques and methods. The objective of the present work was to design and implement a new AMS system at iThemba LABS, the first of its kind on the African continent. The system is described in detail along with the relevant ion optics simulations using TRACE-3D. Beam optics calculations were performed for carbon isotopes, using the TRACE-3D code, in order to optimize the design of the new spectrometer and assess its overall performance. The AMS technique was applied in two unique South African research projects in relation to archaeology and environmental air pollution studies. The AMS technique, combined with the Proton-Induced X-Ray Emission (PIXE) technique, was also applied in an environmental study with respect to the contribution of contemporary and fossil carbon in air pollution in the Lephalale District, close to both the newly built Medupi coal-fired power station (~5 GW, the largest ever build in South Africa), and the existing Matimba coal-fired power station. The discrimination of contemporary carbon and fossil carbon is accomplished by using the AMS technique in measurements of the 14C/C ratios of aerosol particulate matter. The absence of 14C in fossil carbon material and the known 14C/C ratio levels in contemporary carbon material allows us to distinguish between contemporary carbon and fossil carbon and decipher in this manner different anthropogenic contributions. iv The contemporary carbon throughout our sampling campaign in the Lephalale District has been measured to be approximately 53% of carbon aerosol. As many studies have been performed of contemporary carbon and fossil carbon, no other contemporary and fossil carbon source assessment method provides the definitive results that can be obtained from radiocarbon measurements. PIXE analysis for the determination of the elemental composition of particulate matter in samples near the Medupi coal-fired power station in the Lephalale District was also performed for 6 elements, namely, K, Ca, Ti, Mn, Fe, and Zn. In the samples that were analyzed the particulate matter concentrations did not exceed the air quality standards regulation at Lephalale. The recommended daily limit air quality standard by South African legislation is 75 µg/m3. Enrichment Factor (EF) analysis of soil with respect to Fe shows anomalously high values for Zn. AMS was also applied to archaeological studies of early herding camps of the khoe khoe people at Kasteelberg, situated on the southwest coast in South Africa, and are among the best preserved sites of their kind in the world. Sea-shell samples from the Kasteelberg B (KBB) site have been dated with AMS at Lawrence Livermore National Laboratory (LLNL) in an effort to elucidate the relationship between the herder-foragers of the inland and shoreline sites in terms of migration patterns. The radiocarbon dates obtained are in general agreement with the other studies that have been performed on the site, and show that the ages of artifacts are less than 2000 years. The samples for this study originate from various well defined stratigraphic-levels at square A3 at KBB. It was evident from excavation that the artefacts seem to be of the same period and there is no evidence of mixing from different stratigraphic layers. v Radiocarbon dates were calibrated using Calib 6.1 and each was corrected for marine reservoir effect. The date range between the earliest and most recent dates that were obtained span gap is approximately 400 years from AD 825 to AD 1209. The majority of the radiocarbon dates of the KBB site belong to dates of 1002-1100 AD, the other few belong to 825-958 AD, and the last single date of 1209 AD. The new AMS dates from this work suggest the high probability that indeed there was a hiatus between the two occupations designated as lower and the upper KBB. The significant changes seen in material culture styles as well as in the nature of occupation and change in accumulation rate of deposits therefore do not necessarily indicate a cultural replacement caused by the arrival of a new population. This implies that the occupants of lower KBB may also have been Khoe-speakers, and not local San. / GR2018

Stemflow creates biogeochemical hotspots at tree bases. Few studies examine bark structure effects on stemflow generation via stable isotopes. Stemflow volume and isotopic composition (δD, δ18O) were measured over 15 months to address three main objectives: to determine origins and pathways of stemflow, to identify differences in stemflow generation mechanisms between tree species, and to identify differences in stemflow generation mechanisms between meteorological events. Laser ablation spectroscopy showed that, compared to throughfall and precipitation, stemflow was isotopically enriched, signifying isotopic fractionation. A bark-wetting experiment showed bark water storage capacity to be greatest in species with thick, continuous bark. Isotopic composition of precipitation was significantly more enriched in convective storms compared to that of continental or oceanic origin. Therefore, isotopic fractionation of stemflow and stemflow generation mechanisms vary from that of throughfall and precipitation, by interspecific differences in bark, and by meteorological event, potentially influencing existing canopy water storage models.

The material remains of ancient Egypt provide extensive and wide ranging data about the empire throughout its history. However, little evidence is available from ancient Egypt, or any past culture, with which to rebuild an image of social identity or individual experiences. This is especially problematic when the dominant narrative ignores experiences of minorities and minimizes the variation existing throughout the empire. Stable isotope analysis has the potential to reveal variability in lived experience of past peoples by acting as a proxy for behavior that can be analyzed from bone. Such an approach has been applied on individuals from the Romano-Christian Kellis 2 cemetery in the Dakhleh Oasis to explore diversity of lived experiences in relation to age, sex, and gender. Analysis of stable carbon and nitrogen values from bone collagen of 138 adults revealed a predominately C3 plant based diet with the addition of some animal protein. Statistical analysis of these values uncovered discernable differences in the values of young males and older adults which may suggest differences in the biological experiences of these groups and unique social experiences for those individuals. These findings offer a starting point with which to explore social organization at this site and others in ancient Egypt and the methods provide a useful approach to exploring individual experience in the past in ways not possible from other sources.

<p> The isotopic composition and concentration of dissolved helium have been measured in over 250 samples of Atlantic and Pacific seawater. The helium isotope ratios were measured using a double collection "static" mass spectrometer specifically designed and constructed for this purpose. The helium and neon contents of 118 of these samples were determined using the isotope dilution technique, and the helium contents of the remaining samples were determined by peak-height comparison with standard air aliquots. Krypton and xenon concentrations were measured by isotope dilution for the Pacific samples. </p> <p> Two sources of excess nonatmospheric ³He are discerned in the Atlantic Ocean: a primordial component and a component produced by in situ decay of bomb-produced tritium. The former component occurs in three distinct features; two emanating from the south at 1000 m and greater than 4000 m depths, and one emanating from the north at about 3000 m depth. The spatial properties of these features are studied in the framework of simple models. The latter, or "tritiugenic" component is coupled with tritium concentrations measured by others to obtain Tritium-helium Ages, the characteristics of which are compared with hydrographic features. For example, the spreading velocity of the Mediterranean Water is determined to be ⪝ 1.5cm sec⁻¹ in the North-Western Atlantic. </p> <p> The helium and neon concentrations measured in Atlantic Waters indicate that significant variations occur for helium contents, both as a function of depth and latitude. The Antarctic Bottom Water appears to be a source of excess helium. </p> <p> In the Pacific, the distribution of excess ³He is shown to be consistent with injection of primordial ³He into the Deep and Bottom Waters from the East Pacific Rise. The characteristic mid-depth maximum seen in the helium isotope ratio anomaly profiles is shown to be a circulational feature. Upper and lower limits on the amount of excess nonatmospheric ⁴He are set at 5.5 and 2.6% respectively. Application of the simple one-dimensional diffusive-advective model indicate an upward flux of 6±2 and 1.1 ± 0.5 × 10⁶ atoms/cm²/sec for ³He and ⁴He respectively. </p> Pacific seawater is, on the average, 16 and 31% supersaturated in krypton and xenon respectively. Although there is no known process that is capable of such enrichments, the spatial distribution of the krypton and xenon concentrations indicate that a significant amount of the enrichment occurs in situ in Pacific Deep Waters. </p> / Thesis / Doctor of Philosophy (PhD)

The F19 NMR spectrum of SF4 at - 101° C has been assigned as an A2B2 type spectrum, rather than A2X2 as previously reported. Sulphur and boron isotope effects on F19 NMR spectra have been observed for the first time and a new silicon isotope effect has been measured. An expression has been derived for the shape of the spectrum of a nucleus of spin I = 1/2 spin-spin coupled to a nucleus of spin I = 3/2 which is undergoing quadrupole relaxation. The derived expression is used to interpret the F19 spectra of BF3 and Cl03F over a wide temperature range. A new compound, IOF5, has been prepared, and identified by means of its F19 NMR spectrum. / Thesis / Doctor of Philosophy (PhD)

<p> Fractionations of C^13/C^12, O^18/O^16 ratios and Mg between coexisting dolomite and calcite have been determined from rocks of a variety of metamorphic grades in Vermont and the Grenville of Ontario. Working criteria for equilibrium are established. Temperature dependent fractionation expressions are derived (1) for O^18 and C^13 from the C-and O-isotope fractionations concordant with the Mg-calcite solvus thermometer, for T = 130° to 550°C, using natural dolomite-calcite assemblages; (2) for C^13 from hydrothermal partial exchange experiments. Problems with partial exchange reactions are discussed. A thermodynamic analysis of the solvus relations shows that spinodal decomposition probably is important in high Mg-calcites. Quench phenomena in high grade assemblages are complex. The quench temperature may be much lower than the maximum temperature attained. The sizes of some equilibrium systems are delineated.</p> / Thesis / Doctor of Philosophy (PhD)