Research master thesis | Archaeology (research) (MA/MSc)
under embargo until 2024-08-31
2024-08-31T00:00:00Z
Stable carbon (δ13C), nitrogen (δ15N), and oxygen (δ18O) isotopes are well-established proxies for the reconstruction of past diet and environment. δ13C and δ18O can be used to reconstruct the...Show moreStable carbon (δ13C), nitrogen (δ15N), and oxygen (δ18O) isotopes are well-established proxies for the reconstruction of past diet and environment. δ13C and δ18O can be used to reconstruct the plant-based diets of animals and seasonal environmental patterns. These isotopes are regularly measured in the non-organic component of tooth enamel, which is highly resistant to diagenetic alteration. Likewise, δ15N can be used to reconstruct trophic level and food webs. Up until recently, δ15N could only be measured on relatively young samples (<100,000 years old), because it requires organic material, usually bone collagen or dentin, which rarely preserves in the fossil record. However, in 2021, an oxidation-denitrification method was developed. This method allows for the measurement of the nitrogen isotopic composition of the organic material trapped in the crystalline structure of (fossil) tooth enamel. Thus, we can now measure δ13C, δ15N, and δ18O on the same aliquot of tooth enamel. Here, combined δ13C, δ15N, and δ18O isotope data from tooth enamel of 14 serially-sampled fossil equid (Equus sp.) third molars from the ~120,000-year-old Middle Paleolithic Neanderthal site of Neumark-Nord 2, Germany, is presented. Each tooth was sampled along the growth axis and yielded up to 26 sub-samples (total n = 259). Neumark-Nord is a well-preserved archaeological site with a rich vertebrate fauna. It has yielded a large isotopic dataset, which includes some of the oldest stable carbon and nitrogen isotope measurements on bone collagen. This study allows us to expand the isotopic dataset of Neumark-Nord 2 by serially-sampled data, which enables us to reconstruct seasonality for the Last Interglacial (Eemian; MIS 5e/5d transition). δ13C and δ18O of all enamel samples (n = 259) was measured using the cold trap method. Based on these isotope patterns, 72 samples (including all serial measurements of three of the equid teeth) were selected for δ15N measurement, to assess potential seasonal variation in the δ15N values of the enamel. The enamel δ13C, δ15N, and δ18O results are consistent with previously published equid collagen δ13C, δ15N, and bulk enamel δ18O values. A clear seasonal signal is present in the δ18O values of each tooth, with higher values in summer than in winter. This seasonal signal is absent in both the δ13C and δ15N values. This study shows that there is no strong effect of seasonal variation detectable in the δ15N values of nitrogen isotopes in the enamel of equids in temperate environments. This suggests that, in order to measure an accurate average δ15N value, bulk samples of tooth enamel from equids – and likely other large herbivores – in temperature environments do not need to cover an entire year of growth. In addition, the correlation observed between δ13C and δ15N enamel values seems to indicate that, in such environments, the mechanisms controlling carbon and nitrogen isotope fractionation are positively related. Lastly, this study improves the time-resolution of the Neumark-Nord 2 isotopic dataset, allowing for a better reconstruction of the past ecosystem by providing seasonal data.Show less
Carbon Nanomembranes (CNMs) are two-dimensional materials made by cross-linking (interconnecting) the molecules of a Self Assembled Monolayer (SAM). CNMs can be chemically tailored on one or both...Show moreCarbon Nanomembranes (CNMs) are two-dimensional materials made by cross-linking (interconnecting) the molecules of a Self Assembled Monolayer (SAM). CNMs can be chemically tailored on one or both sides leading to a variety of possible properties (e.g. mechanical, conductive, chemical, etc.). Once these properties are understood and controlled, CNMs might be a candidate for (among other things) functional devices based on molecules. In this thesis, it is described how to create laterally patterned CNMs by cross-linking aromatic based self assembled monolayers. Cross-linking is done by in situ low-energy electron irradiation with low energy electron microscopy (LEEM). This novel method allows for new types of experiments giving a brand new perspective. We show that a new structure (possibly CNM) was created after electron irradiation of SAM followed by annealing, furthermore, we have learned that our SAMs show an electron irradiation induced effect. This effect is most accurately described as a front shaped like the irradiated area, slowly shrinking in size until its disappearance. This effect was observed right after irradiation if certain conditions on the illumination time and electron energy were met. This phenomenon was imaged live and down to micrometer scale. These measurements have brought us to the conclusion that this front is not shrinking with a constant speed but is accelerating just before its disappearance. Furthermore, our measurements hint for a connection between the parameters illumination time & electron energy and the visibility and speed of a front.Show less
The aim of this research is to reconstruct the diets of people interred in the early medieval cemetery of Blokhuizen, and the late medieval cemetery of the Paardenmarkt, in Holland. In order to...Show moreThe aim of this research is to reconstruct the diets of people interred in the early medieval cemetery of Blokhuizen, and the late medieval cemetery of the Paardenmarkt, in Holland. In order to accomplish this, 50 human and 19 animal bone samples were analyzed for the stable isotopes of carbon and nitrogen in “collagen”. Two “collagen” isolation methods were applied and a comparison of extraction methods is included in the research. The analysis of stable isotope ratios, and comparison of the reconstructed diets from Blokhuizen and Alkmaar, provide the opportunity to evaluate interpopulation and intrapopulational dietary differences. The goal was to assess general trends in the composition of diet over time, and whether there were differences in diet between the sexes. Ultimately, it was attempted to evaluate to what extent an urban way of life, commercialisation, and changes in subsistence practices impacted diet in medieval Holland. It was established that both populations subsisted on a C3-based diet, with mainly terrestrial protein. Significant dietary differences were found between Blokhuizen and Alkmaar. The population of Alkmaar showed significantly enriched δ15N ratios and had more variable δ13C ratios. This is interpreted as an increase in the consumption of meat and/or marine or freshwater foods in the late medieval diet. There was no significant difference between the sexes in the Blokhuizen sample, whereas a significant difference was found between men and women from Alkmaar: men had significantly enriched in δ15N ratios compared to women. Both male and female diet changed significantly through time as evidenced by higher δ15N ratios, but the δ15N enrichment was higher in the males suggesting they consumed comparatively more animal protein. These data suggest that social differences between males and females changed through time, resulting in dietary differences detectable in stable isotope ratios of human bone “collagen”.Show less
