Sulfur and iron accumulation in three marine-archaeological shipwrecks in the Baltic Sea. The Ghost, the Crown and the Sword.
Artikel i vetenskaplig tidskrift, 2014
Sulfur and iron concentrations in wood from three 17th century shipwrecks in the Baltic Sea, the Ghost
wreck, the Crown and the Sword, were obtained by X-ray fluorescence (XRF) scanning. In near anaerobic
environments symbiotic microorganisms degrade waterlogged wood, reduce sulfate and promote
accumulation of low-valent sulfur compounds, as previously found for the famous wrecks of the Vasa and
Mary Rose. Sulfur K-edge X-ray absorption near-edge structure (XANES) analyses of Ghost wreck wood
show that organic thiols and disulfides dominate, together with elemental sulfur probably generated by
sulfur-oxidizing Beggiatoa bacteria. Iron sulfides were not detected, consistent with the relatively low iron
concentration in the wood. In a museum climate with high atmospheric humidity oxidation processes,
especially of iron sulfides formed in the presence of corroding iron, may induce post-conservation wood
degradation. Subject to more general confirmation by further analyses no severe conservation concerns are
expected for the Ghost wreck wood.