The short-term immersion corrosion of mild and low alloy steels in seawaters is known to be proportional
to the concentration of dissolved oxygen (DO) in the bulk water. Longer-term corrosion is
a function of the activity of sulphate-reducing bacteria and is influenced by the concentration of
nutrients in the bulk water. These influences are examined in more detail for the corrosion of steels
in the brackish waters of the River Thames and for several immersion corrosion sites on the Eastern
Australian seaboard and in the North Sea. The published data sources were supplemented with plausible
assumptions about environmental conditions. New interpretations of the data are provided
based on the previously published model for immersion corrosion. For waters with negligible salinity
and sulphate levels early corrosion loss was shown to depend on the dissolved oxygen content of the
waters, and later corrosion loss was a direct function of nitrogenous nutrient (pollution) levels. This
also applies to longer-term corrosion