Mass spectrometric characterisation and chemometric evaluation of dissolved organic matter

The oceans contain the largest active carbon reservoir on earth. Dissolved organic matter (DOM) is one of the most complex organic mixtures on earth and thus challenges analytical and statistical tools. Changes in the molecular composition reflect biogeochemical gradients and transformation processes. The aim of this thesis is to improve current chemometric approaches to characterise the DOM composition to enable a deeper understanding of organic matter flux. The thesis investigated mixing of DOM constituents in two Arctic fjords along a gradient of glacier-derived meltwater to sea water by mass spectrometry and chemometrics. Chemometric methods identify differences in composition, therefore the choice of the multivariate method is not trivial. A variety of chemometric approaches have been used in the DOM community. Here, they were systematic evaluated to improve the statistical analysis of chemodiversity. Lastly the thesis asks if the relation of chromatography to physico-chemical properties of known structures can constrain the functional feature traits of DOM.