Johannes Pätsch, Hans Burchard, Christian Dieterich, Ulf Gräwe, Matthias Gröger, Moritz Mathis, Hartmut Kapitza, Manfred Bersch, Andreas Moll, Thomas Pohlmann, Jian Su, Ha T.M. Ho-Hagemann, Achim Schulz, Alberto Elizalde, Carsten Eden (2017): An evaluation of the North Sea circulation in global and regional models relevant for ecosystem simulations. Ocean Modelling (2017), doi:10.1016/j.ocemod.2017.06.005


Simulations of the North Sea circulation by the global ocean model MPI-OM and the regional ocean models GETM, HAMSOM, NEMO, TRIM are compared against each other and with observational data for the period 1998-2009. The aim of the study is to evaluate the quality of the simulations in particular with respect to their suitability to drive biogeochemical shelf sea models. Our results demonstrate the benefit of the global model to avoid the specification of lateral open boundary conditions. Due to its stretched grid configuration, which provides a higher grid resolution at the Northwest European Shelf, the global model is able to reproduce the large-scale features, such as the water mass distribution and the thermal stratification in the central and northern North Sea, qualitatively similar to the regional models. The simulation of temperature and salinity near the coast however, shows large biases in almost all models because of the coarse meteorological forcing and too coarse vertical resolutions. The simulation of the Baltic Sea exchange and the spread of freshwater along the Norwegian coast proved difficult for all models except GETM, which reproduces impacts of the Baltic Sea outflow reasonably well.


Florian Dutschke, Johanna Irrgeher and Daniel Pröfrock (2017): Optimisation of an extraction/leaching procedure for the characterisation and quantification of titanium dioxide (TiO2) nanoparticles in aquatic environments using SdFFF-ICP-MS and SEM-EDX analyses. Analytical Methods, doi:10.1039/C7AY00635G


The quantitative recovery of nanoparticles from environmental samples represents a critical step during the implementation of routine analytical monitoring methods for the reliable quantitative determination of nanomaterials released into aquatic environments at the expected low concentration levels. In this work, several approaches based on different extraction agents have been evaluated with respect to their suitability for the recovery of TiO2 nanomaterials from fresh sediment samples. Centrifugal-field-flow-fractionation (SdFFF) hyphenated to inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) has been applied to separate the extracted nanoparticles as well as to overcome the known interference problem related to their Ti-specific detection when using ICP-based techniques. SdFFF-ICP-MS/MS method validation included in particular parameters such as particle recovery or stability of the particle size-distribution. Spike recoveries from the optimized colloidal extraction procedure of up to 95 ± 11% have been achieved. In a case study conducted from 2015 to 2016, the developed method was applied to monitor the release of nano-sized TiO2 materials into a lake environment that is frequently used for recreational activities such as swimming and surfing. The investigated sediment samples show a significant increase of the Ti concentration from 26.2 ± 2.7 mg kg−1 in June 2015 to 40.2 ± 4.6 mg kg−1 in December 2016 originating from TiO2 particles.

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