8 resultados para Extended cubature formula
em Publishing Network for Geoscientific
Resumo:
The Imbrie and Kipp transfer function method (IKM) and the modern analog technique (MAT) are accepted tools for quantitative paleoenvironmental reconstructions. However, no uncomplicated, flexible software has been available to apply these methods on modern computer devices. For this reason the software packages PaleoToolBox, MacTransfer, WinTransfer, MacMAT, and PanPlot have been developed. The PaleoToolBox package provides a flexible tool for the preprocessing of microfossil reference and downcore data as well as hydrographic reference parameters. It includes procedures to randomize the raw databases; to switch specific species in or out of the total species list; to establish individual ranking systems and their application on the reference and downcore databasessemi; and to convert the prepared databases into the file formats of IKM and MAT software for estimation of paleohydrographic parameters.
Resumo:
Remineralization of organic matter in reactive marine sediments releases nutrients and dissolved organic matter (DOM) into the ocean. Here we focused on the molecular-level characterization of DOM by high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) in sediment pore waters and bottom waters from contrasting redox regimes in the northern Black Sea with particular emphasis on nitrogen-bearing compounds to derive an improved understanding of the molecular transformations involved in nitrogen release. The number of nitrogen-bearing molecules is generally higher in pore waters than in bottom waters. This suggests intensified degradation of nitrogen-bearing precursor molecules such as proteins in anoxic sediments: No significant difference was observed between sediments deposited under oxic vs anoxic conditions (average O/C ratios of 0.55) suggesting that the different organic matter quality induced by contrasting redox conditions does not impact protein diagenesis in the subseafloor. Compounds in the pore waters were on average larger, less oxygenated, and had a higher number of unsaturations. Applying a mathematical model, we could show that the assemblages of nitrogen-bearing molecular formulas are potential products of proteinaceous material that was transformed by the following reactions: (a) hydrolysis and deamination, both reducing the molecular size and nitrogen content of the products and intermediates; (b) oxidation and hydration of the intermediates; and (c) methylation and dehydration.