Freshwater biodiversity has been threatened by eutrophication due to excessive nutrients in the environment. Releasing the freshwater species from such pressures requires efforts from industry and... Show moreFreshwater biodiversity has been threatened by eutrophication due to excessive nutrients in the environment. Releasing the freshwater species from such pressures requires efforts from industry and manufacturers to avoid emissions to vulnerable and high-risk regions. The first step is to know which nutrient influences where and the effects thereof on species loss. These impacts can be assessed by methods of life cycle impact assessment (LCIA). This thesis contributes to such knowledge by improving the LCIA method, for instance, by developing more regionalized and comprehensive indicators as well as adding the consideration of both phosphorus (P) and nitrogen (N) and which of these two nutrients is limiting. Show less
Dietary assessment of Late Ceramic Age inhabitants (~ AD 1200–1500) from Lavoutte, Saint Lucia, Lesser Antilles was undertaken on human skeletal remains using stable carbon and nitrogen isotope... Show moreDietary assessment of Late Ceramic Age inhabitants (~ AD 1200–1500) from Lavoutte, Saint Lucia, Lesser Antilles was undertaken on human skeletal remains using stable carbon and nitrogen isotope analysis of bone collagen (δ13Cco and δ15N), and bone and enamel bioapatite (δ13Cap and δ13Cen). The isotope data were interpreted in the context of regional food webs, intra-population dietary variation was assessed relative to individual demographic variables and the results were compared to contemporaneous populations at multiple scales. Moderately enriched δ13Cco and elevated δ15N point to substantial contributions from both non-marine and marine protein sources, including nitrogen-enriched pelagic resources. The lack of correlations between δ13Cco and δ13Cap (or δ13Cen) suggests distinct isotopic differences between protein and energy sources. The smaller range and variance of δ13Cco and δ15N values relative to δ13Capand ∆13Cap-co indicate greater inter-individual heterogeneity in dietary energy sources relative to protein sources. Intra-population dietary variation was not, however, correlated with either age or sex, consistent with communal-based food consumption practices. From a broader perspective, the collagen isotope results are comparable with several islands in the Lesser Antilles but are distinct from others, indicating a large degree of regional variation in dietary protein sources, while the bone (and enamel) apatite results are more variable and overlap with many islands in both the Greater and Lesser Antilles indicating wider variation in average (whole) diets. The relative enrichment in δ13Cap and higher ∆13Cap-co values are strongly indicative that C4 (e.g., maize) or CAM plants were important dietary components. Overall, the isotopic evidence suggests that the Lavoutte population consumed mixed diets including substantial contributions of both C3 and C4/CAM plant resources, as well as terrestrial and marine protein sources. Show less
Aim The influence of soil properties on photosynthetic traits in higher plants is poorly quantified in comparison with that of climate.We address this situation by quantifying the unique and joint... Show moreAim The influence of soil properties on photosynthetic traits in higher plants is poorly quantified in comparison with that of climate.We address this situation by quantifying the unique and joint contributions to global leaf-trait variation from soils and climate. Location Terrestrial ecosystems world-wide. Methods Using a trait dataset comprising 1509 species from 288 sites, with climate and soil data derived from global datasets, we quantified the effects of 20 soil and 26 climate variables on light-saturated photosynthetic rate (Aarea), stomatal conductance (gs), leaf nitrogen and phosphorus (Narea and Parea) and specific leaf area (SLA) using mixed regression models and multivariate analyses. Results Soil variables were stronger predictors of leaf traits than climatic variables, except for SLA. On average, Narea, Parea and Aarea increased and SLA decreased with increasing soil pH and with increasing site aridity. gs declined and Parea increased with soil available P (Pavail). Narea was unrelated to total soil N. Joint effects of soil and climate dominated over their unique effects on Narea and Parea, while unique effects of soils dominated for Aarea and gs. Path analysis indicated that variation in Aarea reflected the combined independent influences of Narea and gs, the former promoted by high pH and aridity and the latter by low Pavail. Main conclusions Three environmental variables were key for explaining variation in leaf traits: soil pH and Pavail, and the climatic moisture index (the ratio ofprecipitation to potential evapotranspiration). Although the reliability of global soil datasets lags behind that of climate datasets, our results nonetheless provide compelling evidence that both can be jointly used in broad-scale analyses, and that effects uniquely attributable to soil properties are important determinants of leaf photosynthetic traits and rates. A significant future challenge is to better disentangle the covarying physiological, ecological Show less
The study of gas-surface interaction dynamics is important both for the fundamental knowledge it provides and also to aid the development of applications involving processes such as sputtering,... Show moreThe study of gas-surface interaction dynamics is important both for the fundamental knowledge it provides and also to aid the development of applications involving processes such as sputtering, plasma etching and heterogeneous catalysis. Elementary steps in the interactions, such as chemical reactions, adsorption and scattering are prototypical of more complex processes and better understanding of them deepens our knowledge of such processes. In addition, experimental measurements of specific interactions can be used to validate advanced computer models. Hence the experiments in this thesis have been carried out under well-defined condition, namely in ultrahigh vacuum and using high-purity single-crystal samples. The thesis is primarily focussed on understanding the interaction of hyperthermal Ar and N (~4-6 eV) with Ru(0001) and Ag(111) via scattering studies. Ar is very inert and its interaction with surfaces is primarily repulsive in nature, while N atoms probe the surface chemisorption well. From the study of Ar scattering dynamics, surface properties have been probed. From N scattering studies, chemisorption dynamics have been investigated. It is found that the electronic state of the incident particle may play an important role in the gas-surface interaction. Separately, the influence of pre-adsorbed CO on Ru(0001) on D2 dissociation have been unravelled. Show less
