The impact of aluminium sacrificial anodes on the marine environment: A case study

Cathodic protection using Al sacrificial anodes is a method of corrosion control that is often applied to submerged metallic structures. This technique leads to the progressive dissolution of the sacrificial anode and the metal(s) constituting the anode are inevitably released into the surrounding aquatic environment with potentially detrimental effects. The chemistry of sediments and waters from a French harbour where Al sacrificial anodes are deployed is examined in this study. In order to assess the potential influence of Al dissolution from the anode on the aquatic environment, total Al concentrations in water and sediment were determined and corresponding Al enrichment factors were calculated. Single and sequential extractions were also undertaken in order to evaluate the mobility of Al in the sediments. Results showed that whilst anodic dissolution does not significantly increase the concentration of Al in the water, both enrichment and an increase in the mobility of Al were evident in sediments sampled from the vicinity of the sacrificial anodes.

► Aluminium sacrificial anodes do not increase the concentration of Al in the waters.
► Al enrichments are evident in sediments near sacrificial anodes.
► Al mobility is enhanced in sediments near sacrificial anodes.