Sulfur and iron accumulation in three marine-archaeological shipwrecks in the Baltic Sea: the Ghost, the Crown and the Sword.

Sulfur and iron concentrations in wood from three 17(th) 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.

Analytical aspects of waterlogged wood in historical shipwrecks.

Conservation methods applied to historical shipwrecks increasingly rely on combining modern analytical techniques to obtain new insights for specially adapted conservation treatments. Crystalline salts formed on waterlogged wood are identified by powder X-ray diffraction while X-ray fluorescence measurements along wood cores show penetration profiles of contaminating elements. Dedicated synchrotron-based X-ray absorption spectroscopy, especially sulfur and iron K-edge XANES, allows speciation of the large amounts of detrimental sulfur and iron compounds that often are found accumulated within the hull timbers, while high resolution X-ray imaging shows the distribution within the wood microstructure.

Sulfur and iron in shipwrecks cause conservation concerns.

Synchrotron-based sulfur X-ray absorption spectroscopy reveals considerable accumulation of organosulfur (e.g. thiols), pyrite and iron(II) sulfides in marine-archaeological wood preserved in seawater, e.

Sulfur accumulation in the timbers of King Henry VIII's warship Mary Rose: a pathway in the sulfur cycle of conservation concern.

In marine-archaeological oak timbers of the Mary Rose large amounts of reduced sulfur compounds abound in lignin-rich parts such as the middle lamella between the cell walls, mostly as thiols and disulfides, whereas iron sulfides and elemental sulfur occur in separate particles. Synchrotron-based x-ray microspectroscopy was used to reveal this environmentally significant accumulation of organosulfur compounds in waterlogged wood. The total concentration of sulfur in reduced forms is approximately 1 mass % throughout the timbers, whereas iron fluctuates up to several mass %.