Identifying the Role of Bacteria in Accelerated Harbor Corrosion

Project Summary

Steel is corroding more than twice as fast as expected in some areas of the Duluth-Superior Harbor. The Duluth Seaway Port Authority estimates that repairs to harbor steel could cost up to $100 million if the problem isn’t addressed. To help determine corrosion causes, divers will scrape biofilm (the bacteria and microorganisms living on underwater surfaces) from highly corroded metal and from uncorroded metal within the harbor. Researchers will analyze these samples, looking for bacteria that are often associated with corrosion. Even if these iron-oxidizing and sulfate-reducing bacterial groups are not directly pitting the harbor's steel, this study could help to pinpoint why the corrosion has accelerated, and guide monitoring efforts by the U.S. Army Corps of Engineers, the Duluth Seaway Port Authority, and the companies that operate docks and slips in the harbor.