Visualization of air-water gas exchange using novel fluorescent dyes

Laser-Induced Fluorescence (LIF) techniques are applied to visualize air-water gas exchange across the aqueous mass boundary layer in wind/wave facilities. Dissolved oxygen is made visible by quenching of the fluorescence of an organic ruthenium complex (tris(4,7-diphenyl-1,10-phenanthroline disulfonic acid) ruthenium(II) dichloride, Ru(dpp ds)3), and acid or alkaline volatile species such as CO2, HCl or diethylamine by the fluorescent pH indicator 1-hydroxy pyrene-3,6,8-trisulfonic acid (HPTS). Fluorescence of both dyes can be stimulated by a 473 nm DPSS laser. The spectral peaks of the fluorescence emission (510 nm for HPTS and 610 nm for Ru(dpp ds)3) are different enough, so that the concentration fields of both dyes can be measured simultaneously using two cameras with different bandpass filters. The paper details the properties of the two dyes and demonstrates their usage with some preliminary visualization experiments

Visualisation of Oxygen Concentration Profiles in the Aqueous Boundary Layer

In environment studies as well as for technical application, the study of air-water gas exchange is crucial. For process studies, a novel visualisation technique of oxygen concentrations in water was realised with high spatial resolution. To resolve turbulent processes in water, also the temporal resolution was pushed to the limit of a imaging frame rate of 185 Hz. For this purpose, the well-established method of laser-induced fluorescence (LIF) was extended introducing in this type of studies a new phosphorescent ruthenium dye that is more than 15 times more sensitive to oxygen than the previously used indicator dye. The chemical synthesis of this metal-ligand complex MLC was adapted to a preparation without intermediate steps. The challenge of this imaging technique for small-scale interactions was to resolve a very thin boundary layer extending less than a millimetre below the water surface. An image processing algorithm was developed that allow the automatic detection of the exact location of the air-water phase boundary within the resolution of 25 um/pixel. Only by this step, an accurate direct determination of an important parameter for gas-exchange studies, the boundary-layer thickness, is feasible. The developed methods were applied to systematic gas-transfer measurements mostly with surfactants, conducted in a range of wind speeds between 0.8-7 m/s in a circular wind-wave facility. The measured gas-transfer velocities compared extremely well to exchange rates derived from mass-balance methods. The novel visualisation technique drastically increased the poor signal quality inherent to standard LIF techniques. This enabled accurate measurements of gas-transfer velocities from aqueous concentration profiles for the first time

Geoarchaeological Evidence for the Decline of the Medieval City of Qalhat, Oman

The medieval city of Qalhat was an important trade town along the sea routes in the Indian Ocean. The reasons for the decline of the city are unclear, as the archaeological evidence is inconclusive. Geological field work was conducted and a digital elevation model analysed to test the hypothesis that the city was destroyed by an earthquake. The study area is located along the passive continental margin of the Arabian Plate. The coast shows a set of Pleistocene marine terraces. These landforms are in indication of lithosphere uplift. Faulted terrace fill deposits and deviating fluvial streams indicate rather recent lithosphere deformation. Processes responsible for the deformation are seen as subduction related forebulge uplift, serpentinite diapirism as well as isostatic response to karstification of limestone. We conclude that earthquake activity along the most prominent structural element, the Qalhat Fault, is a plausible reason for the decline of the medieval city

Data for: Breaking up and making up - reworking of Holocene calcarenite platform into rapidly-forming beachrock breccia on a high energy coastline (St. Lucia, South Africa)

At Mission Rocks Beach at the KwaZulu-Natal coastline in South Africa a coastal calcarenite platform is eroded by high wave energy and simultaneously mended by a quickly forming beachrock. The beachrock forms as infill of erosion-structures within and on top of the platform and thus above the intertidal zone. It was investigated regarding its sedimentology, petrogaphy, geochemistry and age to unravel its process of formation. This dataset contains fieldwork documentation in form of photos and sedimentological profiles, petrographic and SEM images and EDX spectra taken from three samples of beachrock

Critical examination of the term Gender Marketing considering the example of the brands Gillette and Gillette Venus

Die vorliegende Arbeit beschäftigt sich mit dem Einfluss von Gender Marketing-Maßnahmen auf das Kaufverhalten der Kunden. Daraus resultiert die zentrale Fragestellung: Ist Marketing in der Kosmetikbranche ohne die Berücksichtigung von Gender heute noch möglich und sinnvoll

Data For: Beach rock as sea level indicator: a case study at the coastline of Oman (Indian Ocean)

This dataset contains sedimentological and petrographical data that lead to a facies analysis on several beach rock outcrops. The aim was to show that sedimentological facies analysis can lower the vertical error that has to be assumed when reconstructing paleo sea level based on beach rock. The study area is located along the northeastern coastline of Oman and a key area for the investigation of beach rock. This is due to the geomorphology of the region. Twelve marine terraces are observed running parallel to the coastline. On many of these terraces, beach rocks are observed

Dataset for sedimentological evidence of Pleistocene shorelines in Oman

This dataset includes evidence for Quaternary sea-level variations along the shores of the western Indian Ocean. Eight coastal outcrops along the north and east coast of Oman are presented as sedimentological logs. All of these deposits are not situated where they would occur under current sea level conditions. The deposits are regarded as Pleistocene in age, presumably MIS5e, due to dating efforts published prior in Decker et al. (2021). For some sections dating by optically stimulated luminescence seems possible as igneous source rocks supply quartz and feldspar. This work contributes to the ongoing effort to globally identify and subsequently investigate high-resolution records of sea-level changes.The dataset includes:1. gps data and descriptions for all outcrops (Table_general overview outcrops)2. foraminifera species identification and count for outcrop A`Ruays as well as calculation of the Shannon-Weaver Index (H) (Table_Foraminifera)3. sedimentological logs of the presented outcrops if availableTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV