The relation between mass and concentration in x-ray galaxy clusters at high-redshift.

In this Thesis work we have studied the properties of high-redshift galaxy clusters through the X-ray emission from their intracluster gas. In particular, we have focused on the relation between concentration and mass that is related to the density of the universe at the formation time of the clusters and therefore, it is a powerful cosmological probe. Concentration is expected to be a decreasing function of mass but a complete characterization of this relation has not been reached yet. We have analysed 22 clusters observed withe the Chandra satellite at high redshift and we have investigated the concentration-mass relation.

Processes influencing the nitrate concentration in an aquifer for drinking water production in Bremen-Nord - Northern Germany

Groundwater represents the most important raw material. Germany struggles to maintain the best water quality possible by providing advanced monitoring systems and legal measures to prevent further pollution. In areas involved in the intensive growing of plantations, one of the major contamination factors derives from nitrate. The aim of this master thesis is the characterisation of the Water Protection Area of Bremen (Germany). Denitrification is a natural process, representing the best means of natural reduction of the hazardous nitrate ion, which is dangerous both for human health and for the development of eutrophication. The study has been possible thanks to the collaboration with the University of Bremen, the Geological Service of Bremen (GDfB) and Peter Spiedt (Water Supply Company of Bremen). It will be defined whether nitrate amounts in the groundwater still overcome the threshold legally imposed, and state if the denitrification process takes place, thanks to new samples collected in 2015 and their integration with historical data. Gas samples have been gathered to test them with the “N2/Ar method”, which is able to estimate the denitrification rate quantitatively. Analyses stated the effective occurrence of the reaction, nevertheless showing that it only affects the chemical of the deep aquifers and not shallow ones. Temporal trends concentrations of nitrate have shown that no real improvement took place in the past years. It will be commented that despite the denitrification being responsible for an efficacious lowering in the nitrate ion, it needs reactive materials to take place. Since the latter are finite elements, it is not an endless process. It is thus believed that is clearly necessary to adopt a better attitude in order to maintain the best chemical qualities possible in such an important area, providing drinking water.