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Som en av konsekvensene fra menneskeskapte klimaendringer, stiger det gjennomsnittlige havnivået i en økende skala. Som en del av QUANTSEA, et større prosjekt med mål om å rekonstruere nylige havnivåendringer i Norge, ser denne oppgaven nærmere på historien av storm og stormflo. I forbindelse med dette prosjektet ble det tatt to sedimentkjerner fra en mikrotidal saltmyr i sør-vestlige Norge. Det ble funnet flere lag med fragmenterte skjell som ble mistenkt for å være knyttet til stormlag deponert fra større stormer. Formålet med denne masteroppgaven er å undersøke om det eksisterer noen konsistente geokjemiske signaturer knyttet til disse fragmenterte skjell-lagene, og hvordan de skiller seg fra resten av stratigrafien i kjernen, som antas å representere de gjennomsnittlige forholdene i Saltatjørna. For å svare på dette ble kjernene skannet med røntgenfluorescens (XRF) og dataen ble deretter behandlet og analysert. I tillegg ble det gjennomført loss-on-ignition (LOI) analyse på deler av kjerneprøven. Resultatene viser en trend i de analytiske konseptene, der nivåene i de elementære representantene Ca og Sr generelt øker over skjell-lagene. Samtidig synker de andre elementære representantene som ble brukt, Fe, Zr, Cl og Br. LOI analysene viste også mye mindre organisk innhold over skjell-lagene. Sammen med andre observasjoner, CT skanning, historiske fotografier, og målinger av «sill» og «wrack line» konkluderer oppgaven med at det er en korrelasjon. Nivåene av Sr og Ca indikerer marin påvirkning, mens den synkende verdien av Fe er en indikasjon for synkende input av terrigene materialer. Kombinert med kunnskap om tidevann-nivået rundt studieområdet, konkluderes det med at denne marine påvirkningen ikke er et resultat av regelmessig tidevann, men helle sjeldnere, større stormfloer. As one of the consequences of human-caused climate change, average sea levels are rising at an increasing rate. As part of QUANTSEA, a larger project that aims to reconstruct more recent sea level changes in Norway, the focus of this thesis is to look into records of storms and storm surges. For the project, two cores were sampled from a microtidal saltmarsh in south-western Norway. The several shell layers observed in the cores were suspected to be connected to storm layers deposited from bigger storms. The goal of the thesis is to research whether there are any consistent geochemical signatures associated with these distinct fragmented shell layers, and how they differentiate from the rest of the core stratigraphy, which is presumed to represents average conditions in Saltatjørna. In order to answer this, the cores were scanned with X-ray fluorescence (XRF), and the data was then transformed and analyzed. Some samples also underwent a loss-on-ignition (LOI) analysis. The results show a trend in the analytical concepts, were the levels of the elemental proxies Ca and Sr generally increased over the shell layers, while the other proxies used, Fe, Zr, Cl and Br, all decreased. The LOI also showed much less organic content over the shell layers. Together with other observations, such as CT scans, historical photographs, and measurements of the sill elevation and wrack line, the thesis concludes that there is a correlation. The Sr and Ca levels indicate marine influence, whereas the decreasing Fe is a proxy for decreasing terrigenous materials. Combined with knowledge of the tidal range around the study area, it is concluded that this marine influence is not the result of regular tides, but rather rarer, larger storm surges.

Objective. Attenuation masks can be used in x-ray imaging systems to increase their inherent spatial resolution and/or make them sensitive to phase effects, a typical example being Edge Illumination x-ray phase contrast imaging (EI-XPCI). This work investigates the performance of a mask-based system such as EI-XPCI in terms of Modulation Transfer Function (MTF), in the absence of phase effects. Approach. Pre-sampled MTF measurements, using an edge, were performed on the same system implemented without masks, with non-skipped masks and finally with skipped masks (i.e. masks in which apertures illuminate every other pixel row/column). Results are compared to simulations and finally images of a resolution bar pattern acquired with all the above setups are presented. Main results. Compared to the detector’s inherent MTF, the non-skipped mask setup provides improved MTF results. In comparison to an ideal case where signal spill-out into neighbouring pixels is negligible, this improvement takes place only at specific frequencies of the MTF, dictated by the spatial repetition of the spill-out signal. This is limited with skipped masks, which indeed provide further MTF improvements over a larger frequency range. Experimental MTF measurements are supported through simulation and resolution bar pattern images. Significance. This work has quantified the improvement in MTF due to the use of attenuation masks and lays the foundation for how acceptance and routine quality control tests will have to be modified when systems using masks are introduced in clinical practice and how MTF results will compare to those of conventional imaging systems.