Yes / In this study, period-specific dietary trends, along with socio-economic and religious influences on foods consumed by Pictish and medieval inhabitants from Portmahomack are investigated. Bone collagen from human adults (n = 137) and fauna (n = 71) were analysed for stable carbon and nitrogen isotope ratios to enable dietary reconstructions of the whole adult skeletal assemblage. Adult mean δ13C and δ15N values from all periods (6th to 17th century) were −19.5‰ ± 1.3‰ and 13.3‰ ± 1.7‰ respectively. A diachronic change in diet between early medieval Pictish lay and monastic communities (periods 1–3) and the later medieval parish layfolk (periods 4–5) was found that suggests changing socio-economic and religious influences, along with age and gender differences in diet that reflect possible divisions in labour and status. Faunal data also reflected a diachronic change in diet, most likely related to a change in animal husbandry practices over time. This is the first large-scale study on the Portmahomack assemblage and presents new isotope data to provide a more comprehensive insight into Pictish and medieval subsistence patterns, along with evidence of how religious and social foci may influence diet over time. Such comprehensive investigations can only be adopted by analysing the whole skeletal assemblage, providing robust faunal baselines and inter- and intra-site comparisons. Most importantly, this significant new evidence fundamentally changes our knowledge of diet and subsistence in medieval Scotland and the potential influences therein. / Supported by grants from the NERC Isotope Geosciences Facility Steering Committee (IP‐1302‐0512), the Arts and Humanities Research Council (AH/I019103/1), and Historic Scotland (AMJ/4208/4).

West Back Bay in Biloxi, Mississippi is an oligohaline estuary. Salt-tolerant submerged aquatic vegetation (SAV) and saltmarsh grasses are found ubiquitously throughout this estuary with Vallisneria americana and Juncus roemerianus being the dominant SAV and saltmarsh vegetation. No studies have directly evaluated the role of these vegetation species in the food web. Carbon and sulfur stable isotope analyses were used to identify primary source contributions to fishes Menidia beryllina, Fundulus grandis, and Lepomis macrochirus. Isotopic niche overlap was compared between fishes and basal carbon sources bimonthly from May 2021 through May 2022. Fishes had greater than 50% isotopic niche overlap with SAV compared to fringing saltmarsh. Overlap was less than 23% for Juncus roemerianus and negligible for other saltmarsh species. These results suggest that Vallisneria americana in Back Bay is a primary driver of these fishes’ diets and should be a focus of habitat conservation efforts in oligohaline ecosystems.

The transition from the Neoproterozoic to the early Cambrian world was a critical time in the co-evolution of life and the environment, when dramatic changes in the environment, including global glaciations and rising atmospheric oxygen levels precipitated the conditions in which variety of complex life emerged, diversified, and proliferated. However, questions persist regarding the timing and duration of those environmental events, and thus the extent of their direct effect on the evolution of life. These changing environmental conditions also produced unique taphonomic conditions that preserved a wide variety of organisms, and also produced unusual early diagenetic features that can be difficult to distinguish from fossilized organisms. In order to better resolve the link between life and the environment during the Neoproterozoic to Cambrian transition I present three chapters. The first chapter of this dissertation examines the carbonate clasts from a glacial diamictite deposited at the end of the Cryogenian Period in South China. By determining the source locality of those carbonate clasts using stable carbon and oxygen isotope compositions, we can better understand the extent of the Marinoan Glaciation and the intensity of its impact on the Earth's surface. In the second chapter of this dissertation, I investigate the changing chemical conditions of ocean waters following both the Marinoan glaciation and potentially one of the most intense disruptions to the carbon cycle in Earth History, the Ediacaran Shuram carbon isotope anomaly. I use Hg concentrations and stable isotope compositions to determine changes in sediment sourcing along with changes in marine redox, such as the development of photic zone euxinia. In the third chapter, I investigate the identity of Brooksella alternata, a purportedly cnidarian fossil that was later suggested to be a hexactinellid sponge fossil. My morphological and compositional analysis reveals B. alternata to be a concretion and thus a pseudofossil. / Doctor of Philosophy / The Earth experienced major changes between 635 and ~514 million years ago; the last global scale glaciation in the history of Earth ended, early animals arose, primary producers such as algae grew larger and more complex, and the first animals that were mobile and with hard skeletal parts evolved and diversified tremendously. Concomitantly, the environment on the Earth changed dramatically: the carbon cycle experienced one of the greatest disruptions in all of Earth history and the oceans and atmosphere gradually became more oxygen-rich, though areas with low levels of dissolved molecular oxygen and high concentrations of dissolved iron or hydrogen sulfide persisted, which may have impeded the diversification of complex animals. The exact timing and intensity of these changes are not fully resolved, and by investigating this time interval in the geologic record, we can better understand how the world changed and how life at the time responded. These changing environments also produced unique conditions which led to fossils being preserved in unique ways, though these conditions also produced non-biological structures that superficially resemble fossils. The first chapter of this dissertation investigates the source of clasts made of carbonate rock from a glacial diamictite (the poorly sorted mixture of the fine-grained and coarse-grained deposits left behind as glaciers recede) in South China deposited at the end of the last global scale glaciation about 635 million years ago. By determining the source, we can evaluate how far glacial activity transported sediments. I found that the previously suggested source of these clasts does not match the geochemical fingerprint of the carbonate clasts. I propose that these carbonate clasts may have come from a source that has since become "extinct" because of glacial erosion, or they may have come from another continent (for example, India). These scenarios highlight the magnitude of the global glaciation. In the second chapter, I investigated the mercury concentrations and stable isotope compositions from organic rich shales deposited ~550 million years ago. Mercury is an emerging tool for evaluating the level of dissolved molecular oxygen in ancient oceans. In this study, I found evidence of locally complex marine oxygen levels, including evidence for photic zone euxinia, meaning waters where oxygen was absent and hydrogen sulfide was present. Such conditions are toxic to animals and may have delayed the diversification of complex animal life. In the final chapter, I analyzed the ~503 million-year-old fossil Brooksella alternata. It was first described more than 100 years ago as a jelly-fish fossil. More recently it was suggested to be a sponge fossil (though it has been ascribed many other identities). Based on morphological analysis of a large collection, I determined that Brooksella alternata is not a fossil but rather a concretion with unusual shape.

Agricultural practices have intensified over the last 50 years, increasing crop production and altering the Canadian Prairie landscape by removing non-cropped habitats and wetlands. The productivity, trophic structure and diversity have changed through increased agrochemical inputs and reductions in yearly rotation and diversification of crop types. Most intensive agricultural practices have negative effects on invertebrate communities that can indirectly affect higher trophic organisms, such as birds. Many populations of aerial insectivorous bird species have been experiencing rapid declines in the last 30–40 years. Dependency on high abundances of aerial insects for reproduction and survival is a common link among all species of this guild. My thesis examined aerial insect abundance as a potential link between agricultural land use and the reproductive ecology, nestling body condition, and diet of an aerial insectivore species, the tree swallow (Tachycineta bicolor). My broad goal was to determine whether agriculture has deleterious effects on timing of breeding, reproductive investment and success, and nestling quality, as mediated by food supply and differences in diet. Aerial insect abundance and biomass estimates obtained from passive insect traps which capture primarily aquatic dipterans were similar between agricultural and reference sites during all stages of breeding. However, estimates derived from sweep-net sampling in terrestrial habitats in 2013 indicated higher abundances of aquatic and terrestrial Diptera at a reference site relative to agricultural sites. Multiple measures of tree swallow productivity were not related to agriculture land use but nestling body condition was significantly lower on agricultural sites. Using stable isotope analysis (delta 13C and delta 15N), I found site and age specific differences in swallow diets and isotopic niche widths but variation was not consistently related to agricultural land use. Aquatic insect prey (Diptera and Odonata) made up the majority of the diet of swallows but nestlings had a larger proportion of terrestrial Diptera which resulted in larger isotopic niche widths compared to adults. The assimilated isotopic diet of nestling and adult swallows were not strong predictors of body size, mass or condition, suggesting that site differences in the diet do not appreciably affect condition. Nestlings raised on agricultural sites had lower body condition that was not directly linked to their diet alone. This suggests other unmeasured factors related to agricultural land use may affect nestling tree swallows. This study tested responses in an aerial insectivore species to land use and potential shifts in the insect community, which may provide important information for conservation and management decisions for many species within the aerial insectivore guild.

No description available.

This thesis concerns the application of a new technique for measuring the stable isotopes of Sr, specifically pertaining to mass dependent fractionation in high temperature processes on the Earth and Moon. Processes such as mantle melting and differentiation on Earth and the formation of the Lunar Magma Ocean are investigated by the application of a double-spike TIMS method to terrestrial and lunar material to obtain high-precision ⁸⁷Sr/⁸⁶Sr, ⁸⁸Sr/⁸⁶Sr and ⁸⁴Sr/⁸⁶Sr data. Measurements of mantle-derived mafic material provide insights into the ⁸⁸Sr/⁸⁶Sr composition of the silicate mantle. Ocean Island Basalts possess restricted δ⁸⁸Sr compositions, whilst Mid-Ocean Ridge Basalts from the Pacific, Atlantic and Indian ridges reveal variations in δ⁸⁸Sr, the majority of which is seen within the FAMOUS section of the Mid-Atlantic Ridge. These variations are attributed partly due to the effects of plagioclase crystallisation and partly due to mantle source heterogeneity. Analyses of mineral separates from three different igneous systems provide an understanding of δ⁸⁸Sr fractionation at a mineral-scale. The possibility of δ⁸⁸Sr fractionation as a result of magmatic differentiation has also been assessed, and found to occur between the basalt and rhyolitic end-members of the Icelandic Hekla suite. Variations in the ⁸⁷Sr/⁸⁶Sr ratios of these rocks are also found, and considered most likely to be due to contamination. Analyses of lunar rocks indicate that the highland suite appears to be relatively uniform in δ⁸⁸Sr, whilst significant fractionation to light δ⁸⁸Sr compositions occurs in the mare basalts. Such variations are thought to be associated with the crystallisation of plagioclase during the differentiation of the lunar magma ocean. Lastly, precise ⁸⁷Rb/⁸⁶Sr and ⁸⁷Sr/⁸⁶Sr data yield a model age for the Moon of 4.523 ± 0.019 Ga.

The Mae Tao watershed, northwestern Thailand, has become contaminated with cadmium (Cd) from the zinc mining activities area in the nearby Thanon-Thongchai mountains. Consumption of Cd-contaminated rice has led to documented human health impacts. The aim of this study was to clarify transfer pathways from creek and canal waters to the paddy field soils near Baan Mae Tao Mai village and to determine the relationship between Cd forms in the soil and uptake by rice plants. Soils, irrigation canal sediments and water samples were collected during the dry season and at the onset of the rainy season. Rice samples were collected at harvesting time and samples of soil fertiliser were also obtained. Water samples were filtered, ultrafiltered and analysed by ICP-MS whilst sub-samples of dried, ground soils and sediments were first subjected to micro-wave assisted acid digestion (modified US EPA method 3052). XPRD and SEM-EDX methods were used for mineralogical characterisation and selective chemical extractions have assisted in the characterisation of solid phase Cd associations. Transfer mainly occurred in association with particulate matter during flooding and channel dredging and, in contrast with many other studies, most of the soil Cd was associated with exchangeable and carbonate-bound fractions. Moreover, there was a significant positive relationship between soil total Cd and rice grain Cd (R2=0.715), but a stronger relationship between both the Tessier-exchangeable soil Cd and the BCR-exchangeable soil Cd and rice grain Cd (R2=0.895 and 0.861, respectively). Stable Isotope Exchange (gives isotopically exchangeable Cd - E value) is generally considered to provide a better measure of bioavailability. The results of this study showed that SIE gave values which significantly positive correlated with the Tessier exchangeable fraction. Biochar has a porous structure and acidic functional groups on its surface which give it a high capacity to affect heavy metal adsorption when added to soils. Biochar samples were produced from rice husk (RHC) and miscanthus (MC) since these are cheap and readily available materials in Thailand. Indeed rice husk char is already used for rice seed germination by local farmers. Evaluation of the chemical and physical properties of the chars showed that the lower temperature (350°C) chars had greater proportions of oxygen-containing functional groups than those produced at 700°C. Moreover the low temperature RHC had the greater cation exchange capacity than the MC produced at the same temperature. In abiotic feasibility tests, it was shown that RHC was more effective than MC at lowering soil available Cd. The former reduced the E values for the medium-Cd soils by 4.7% and 16.0% when 1% and 5% RHC, was added, respectively. From pot experiments, in medium-Cd soils, 1% and 5% RHC amendment showed the potential to decrease Cd uptake by rice roots. However, further work involving addition of a greater proportion of biochar with a higher number of replicates is needed to reach more robust conclusions.

Soil respiration is an important source of atmospheric CO2, with the potential for large positive feedbacks with global warming. The size of these feedbacks will depend on the relative sensitivity to temperature of very large global pools of highly stable soil organic matter (SOM), with residence times of centuries or longer. Conflicting evidence exists as to the relationships between temperature sensitivity of respiration and stability of SOM, as well as the temperature sensitivity of individual stabilisation mechanisms. This PhD considers the relationship between different stabilisation mechanisms and the temperature sensitivity of SOM decomposition. I used physical fractionation to isolate SOM pools with a variety of turnover rates, from decadal to centennially cycling SOM, in a peaty gley topsoil from Harwood Forest. Mean residence times of SOM as determined by 14C dating was most strongly affected by depth, providing stability on a millienial scale, while OM-mineral associations and physical protection of aggregates provided stability to around 500 years. Chemical characteristics of organic material in these fractions and whole soils (13C CP-MAS NMR spectroscopy, mass spectrometry, FTIR spectroscopy, thermogravimetric analysis, ICP-OES) indicated the relative contribution of different stabilisation mechanisms to the longevity of each of these fractions. Two long-term incubations of isolated physical fractions and soil horizons at different temperatures provided information about the actual resistance to decomposition in each SOM pool, as well as the temperature sensitivity of respiration from different pools. Naturally 13C-labelled labile substrate additions to the mineral and organic horizons compared the resistance to priming by labile and recalcitrant substrates. Manipulation of soil pore water was investigated as a method for isolating the respiration of SOM from physically occluded positions within the soil architecture. Contadictory lines of evidence emerged on the relative stability of different SOM pools from 14C dating, incubation experiments and chemical characterisation of indicators of stability. This led to the interpretation that physical aggregate protection primarily controls SOM stability within topsoils, while mineral and Fe oxide stability provides more lasting stability in the mineral horizon. Less humified and younger SOM was found to have a higher sensitivity to temperature than respiration from well-humified pools, in contrast to predictions from thermodynamics.

The overall aim of the study was to provide better insights to the ecological role and impact of cyanobacteria in Baltic Sea (BS) bay, coastal and open sea areas. Biomass and heterocyst development of diazotrophic, heterocystous cyanobacteria were monitored over several years simultaneously as physical parameters such as nutrients and temperature. Nitrogen fixation was estimated as well as its transfer in the BS food web. Even after decades of debate there is still controversy whether eutrophication of lakes and estuaries/coastal areas should be managed by reducing phosphorus only or also nitrogen. Central to this debate is whether nitrogen fixation by cyanobacteria can replace shortages of combined nitrogen quickly enough to make phosphorus the limiting nutrient and nitrogen removal pointless or even harmful. Also, it is not clear if available combined nitrogen inhibits heterocystous cyanobacterial nitrogen fixation and if it is used for their growth in situ. A large ecosystem-wide experiment started in Himmerfjärden bay in year 1997, where the N-loadings and release depth from a modern sewage treatment plant (STP), located in the inner part of the bay, were modulated. The STP creates a steep gradient of nutrients and stable nitrogen isotopes, which can be used to study uptake of combined nitrogen, as well as biomass development and primary productivity. A 35-year long data series was used to achieve good insights into phytoplankton development and primary productivity in the Baltic Sea over the last couple of decades. These in vivo long time series, based on monitoring data, in combination with shorter series (2-3 seasons, including measurements of colony stoichiometry and stable isotopes), have resulted in a unique meta-dataset, allowing for high-resolution observations into the role of the cyanobacteria in the Baltic Sea ecosystem. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

<p>The main aim of this thesis was to contribute with detailed information of regional environmental change during the Holocene through studies of speleothems and their growth environments from two caves, Korallgrottan and Labyrintgrottan in northwestern Sweden, and a cellar vault in Uppsala. This was done through studies of stable isotopes and luminescence properties in the speleothems in combination with a detailed monitoring study in Korallgrottan.</p><p>The monitoring study suggests that stalagmites fed by stalactites with slow and stable drip rates from deep inside the cave may be suitable as palaeoclimate archives. Similarities between oxygen isotope signals of contemporary samples from Labyrintgrottan and Korallgrottan emphasize the potential of speleothems from Labyrintgrottan to also provide high resolution regional palaeoclimate information.</p><p>Except for a number of cold events stalagmite δ¹⁸O records from northern Scandinavia indicate that temperatures were warmer than today between 9500 and 6000 years ago. During this period the interval between 7800 and 6000 years ago seems to have been the warmest. The area above Labyrintgrottan was most likely covered by much denser vegetation than today at the time of stalagmite growth (9500-7500 years ago) and was, unlike today, probably situated below the local tree-limit between 9000 and 8000 years ago. The δ¹⁸O record of a stalagmite from Korallgrottan covering the last 4000 years agrees with the concept of a warmer period, the so called Medieval Warm Period, centred around AD1000 and a colder period, the so called Little Ice Age, somewhere between AD1000 and today.</p><p>Studies of luminescence properties in fast growing speleothems from Uppsala indicate that the variations in luminescence intensity are annual and that the annual lamiae of the luminescent record represent a flush of organic material.</p>