Sulfur and iron analyses of marine archaeological wood in shipwrecks from the Baltic Sea and Scandinavian waters

► We examine sulfur and iron accumulation in shipwreck timbers and sediments. ► We use sulfur K-edge XANES spectroscopy for speciation of characteristic sulfur groups. ► Sulfur accumulation is high in outer layers of marine-archaeological wood, probably degraded by erosion bacteria. ► Hydrogen sulfide reacts to organic-bound sulfur in lignin-rich parts. ► Pyrite and other iron(II) sulfides form when iron(II) ions are available.