Long-term corrosion of steels in deep, cold, low oxygen sea waters

Corrosion of steels in deep, cold, low oxygen sea waters over many decades often is attributed to microbiologically influenced corrosion (MIC). Herein it is argued that the available evidence does not support this proposition since (a) the few available in-situ deep sea field observations are consistent with long-term corrosion under abiotic conditions and (b) independent environmental studies indicate dissolved inorganic nitrogen, a necessary nutrient for MIC, is likely negligible or very low in deep sea waters. On that basis it is proposed that the rusticles observed on some shipwrecks, such as the Titanic, largely are the result of formation of ferrous hydroxides from ferrous ions released, very slowly, from the oxidation of magnetite rusts to maghemite. Direct evidence for this proposition is not available in-situ but is consistent with field observations and laboratory results.