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

2014; Nature Portfolio; Volume: 4; Issue: 1 Linguagem: Inglês

10.1038/srep04222

2045-2322

Yvonne Fors, Håkan Grudd, A. Rindby, Farideh Jalilehvand, Magnus Sandström, Ingemar Cato, Lennart Bornmalm,

Archaeology and ancient environmental studies

Sulfur and iron concentrations in wood from three 17th century shipwrecks in the Baltic Sea, the Ghostwreck, 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.