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Some three hundred mainly steel shipwrecks from both World Wars lie buried at shallow depths along the Belgian North Sea coast. They were examined recently to estimate corrosion rates over periods in excess of 100 years. The rate was estimated by comparing the measured in-situ steel plate thicknesses with archived ship information. The estimates show distinctly lower long-term corrosion rate compared to that predicted by the Melchers (Modeling of marine immersion corrosion for mild and low alloy steelspart 1: phenomenological model. Corrosion. 2003;59(4):319-334) corrosion model, when parameterised for local North Sea conditions. Concretion after 50 years has a multi-layer structure for which SEM-EDS and XRD measurements show the innermost layer, close to the metal surface, consisting of akaganeite, and the outer layer mostly of calcium carbonates, silicates, and some siderite. In between there is a considerable layer of hard magnetite. The latter is proposed as the reason for the low long-term corrosion rate (0.016 mm y-1) in an environment with calcium carbonate available in abundance.

Historic shipwrecks form an anthropogenic landmark in marine environment, yet their influence on the local geochemistry and microbiology remains largely unexplored. In this study, sediment and steel hull samples were taken around the V-1302 John Mahn, a World War II shipwreck, at increasing distance from the wreck, in different directions. Polycyclic aromatic hydrocarbons (PAH’s), explosives, and heavy metal levels were determined and related to the microbial composition. Benz(a)anthracene and fluoranthene remain present at the mg kg-1 level, probably originating from the coal bunker. These PAH’s indicate that the wreck is still influencing the surrounding sediments however the effects are very dependent on which side of the wreck is being studied. Known PAH degrading taxa like Rhodobacteraceae and Chromatiaceae were more abundant in samples with high aromatic pollutant content. Moreover, sulphate reducing bacteria (such as Desulfobulbia), proven to be involved in steel corrosion, were found present in the biofilm. This study shows that even after 80 years, a historic shipwreck can still significantly steer the surrounding sediment chemistry and microbial ecology.

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e journal is open to international research submitted by individual scholars as well as by interdisciplinary teams, and especially wishes to promote work by junior researchers and new and innovative projects. Challenging research themes can be explored in dedicated issues. eoretical approaches are welcomed as much as presentation of material culture assemblages.