The same deposit that builds up in many tea kettles or water pipes in areas where calcium-rich water is the norm might be just the (cheap) ticket to rid contaminated seawater of toxic metals. This is according to a study by a research group led by Charlotte Carré of the University of New Caledonia in the French Pacific territory of New Caledonia and published today in Springer’s journal Environmental Chemistry Letters. The researchers dipped electrodes made from galvanized steel into contaminated seawater and ran a weak current through it. Within seven days, up to 24 percent of the nickel it initially contained was trapped in a calcareous build-up of limestone.