Lead Shielding (Marine)

Lead in the marine setting serves two roles and carries one legacy-pollution concern. As ballast it is cast into keels and bilge weights for stability because of its density (11.3 g/cm3). As radiation shielding it is used aboard nuclear-powered naval vessels and in detectors, where low-background lead salvaged from ancient shipwrecks is prized because it has lost most of its radioactive lead-210. The pollution concern is corrosion and loss of lead ballast, anchors, and shot, which adds the heavy metal lead to sediments where it is toxic to benthic life and bioavailable under acidic or sulfidic conditions.