ALBERT

Description: This study investigates Late Quaternary sediments from Vankervelsvlei, a peatland located at 152 m above present sea level at the southern Cape coast of South Africa. A 15 m long sediment record was recovered from the site in 2016 and analysed using a multi-proxy approach. This includes analyses of water content, loss on ignition, grain size, organic (C, N and their isotopic composition) and inorganic (Al, Fe, Sr, Ti) elemental composition as well as compound-specific stable hydrogen and carbon isotopes from leaf wax-derived n-alkanes and compound-specific stable oxygen isotopes from hemicellulose-derived sugars. Stable hydrogen and oxygen isotopes are additionally coupled in a δ2Hn-alkane–δ18Osugar paleohygrometer. Parts of the data derive from a pioneer study by Strobel et al (2019) and have subsequently been extended by Strobel et al (submitted). Distinct environmental changes occurred at Vankervelsvlei during the Late Quaternary and the applied multi-proxy approach enables to reconstruct past variations in the atmospheric source of precipitation and local moisture availability at the site, which is coherent with other records located along the southern Cape coast of South Africa.

Description: Appropriate field data are required to check the reliability of hydrodynamic models simulating the dispersion of soluble substances in the marine environment. This study deals with the collection of physical measurements and soluble tracer data intended specifically for this kind of validation. The intensity of currents as well as the complexity of topography and tides around the Cap de La Hague in the center of the English Channel makes it one of the most difficult areas to represent in terms of hydrodynamics and dispersion. Controlled releases of tritium - in the form of HTO - are carried out in this area by the AREVA-NC plant, providing an excellent soluble tracer. A total of 14 493 measurements were acquired to track dispersion in the hours and days following a release. These data, supplementing previously gathered data and physical measurements (bathymetry, water-surface levels, Eulerian and Lagrangian current studies) allow us to test dispersion models from the hour following release to periods of several years which are not accessible with dye experiments. The dispersion characteristics are described and methods are proposed for comparing models against measurements. An application is proposed for a 2 dimensions high-resolution numerical model. It shows how an extensive dataset can be used to build, calibrate and validate several aspects of the model in a highly dynamic and macrotidal area: tidal cycle timing, tidal amplitude, fixed-point current data, hodographs. This study presents results concerning the model's ability to reproduce residual Lagrangian currents, along with a comparison between simulation and high-frequency measurements of tracer dispersion. Physical and tracer data are available from the SISMER database of IFREMER (www.ifremer.fr/sismer/catal). This tool for validation of models in macro-tidal seas is intended to be an open and evolving resource, which could provide a benchmark for dispersion model validation.

Description: Air quality data used to identify time windows of the best air quality in the day