Biological Organisms

All biological organisms, either animals or plants, alter the composition of surrounding water, which may result in increased or decreased corrosion rates. Some organisms merely provide a protective layer, limiting oxygen from reaching the metal’s surface. Others increase the oxygen or sulfide content, increasing the corrosive attack on metals. Microorganisms will be discussed further in Section 2.9.6. Figure 5 shows some corrosivity factors and their effect on the uniform corrosion rate of carbon steel in the Pacific Ocean.