The chemistry of the Vasa

摘要: Analyses of wood from the Swedish warship Vasa revealed a complex chemical composition with increased acidity and depolymerisation hemicellulose polyethylene glycol (PEG). Pronounced were found in ferriferous segments below surface region high iron-sulfur-ratios. Decomposition products such as low molecular acids, xylan PEG oligomers identified by NMR MALDI-TOF mass spectrometry aqueous extracts. The concentrations acids (formic, glycolic oxalic) enhanced compared to unconserved waterlogged recent oak. highest concentration formic acid was at sites shown changes weight distribution (MWD). Statistical simulations degradation model experiments on holocellulose Fenton's reagent support initiated hydroxyl radicals. Multi-elemental analyses performed scanning electron microscopy showing different patterns relation depth degradation. (0-5 mm) characterized presence particles lumina (gypsum, elemental sulfur, iron sulfur compounds) background evenly distributed compounds. Below surface, depolymerisation, crusts compounds lumina, (10-100 nm) frequently observed cell walls. EXAFS analysis speciation showed that is present hydrated iron(II) ions iron(III) complexes. Sulfur K-edge XANES extracted reduced organic (ROSC) intermediate oxidized species bind macromolecules. conclusion processes are regions sulfur. In significant amounts ROSC less common indicating antioxidant properties, i.e. an opposite effect regard iron. Full-scale extraction chelators conserved artefacts efficient but time-consuming (years). Minor effects treatment MWD oak analysed size-exclusion chromatography.