Impact of Galvanic Anode Dissolution on Metal Trace Element Concentrations in Marine Waters

Abstract

Submerged harbor steel structures often employ cathodic protection using galvanic anodes to guard against corrosion. A laboratory experiment, with three different cathodic protection configurations by galvanic aluminum-based anodes, was performed to evaluate the potential metal transfer from the anodic alloy dissolution into the surrounding marine water. The anode dissolution rate is proportional to the imposed current demands and induced a significant Al, In, and Zn transfer in the dissolved and particulate fractions of the corrosion product layers covering the anode surface. These layers were poorly adherent, even under low hydrodynamic conditions. Consequently, at the anode vicinity, the suspended particle matter and dissolved fraction of surrounding marine waters showed strong enrichments in Al and Zn, respectively, the values of which could potentially affect the adjacent biota. After the anode activation period, however, the metal inputs from galvanic anode dissolution are rapidly diluted by seawater renewal. At regional scale, these metal fluxes should be negligible compared to river and wastewater fluxes. These results also showed that it is difficult to assess the impact of the anode dissolution on the concentrations of metals in the natural environment, especially for metals included in trace amounts in the anode alloy (i.e., Cu, Fe, In, Mn, and Si) in the aquatic compartment.

Electrokinetic generation of iron-rich barriers in soils: realising the potential for nuclear site management and decommissioning

“…We also note recent advances in the use in sacrificial anodes for soil, groundwater and wastewater treatment, 51 including iron 12,52,53,54 magnesium, 55 and aluminium. 56,57 A range of problematic contaminants are known to reductively precipitate in the presence of reduced iron minerals and phases, or sorb to iron-rich phases (and other metal oxides and oxyhydroxides, including those of Al) 54,58 .…”

A Metabolomic Investigation of the Effects of Corrosion Products of Galvanic Anodes on the Metabolome of Magallana gigas (Formerly Crassostrea gigas)

“…Passive samplers were used to confirm the presence of metals in dissolved form [19] throughout the experiment. Four passive samplers with the reference LSNM-NP openpore Loaded DGT device for metals (A) in solution (DGT ® Research) were successively collected per tank (every four days) to determine total concentrations of Al, Zn, and In (see Section 2.5.2).…”

Étude de la spéciation dans l’eau de mer de l’aluminium et du zinc libérés par la dissolution d’une anode galvanique

“…Concentrations totales en aluminium (en mg L À1 ) relevées dans les eaux côtières sur des sites pollués. Dans leur étude, Deborde et al [46] ont démontré que la dissolution de la même anode entraînait un enrichissement de l'eau en aluminium particulaire qui diminuait sous l'effet des conditions de renouvellement et d'agitation, alors qu'elle avait pour conséquence d'enrichir la fraction dissoute en zinc dans les premières heures de l'activation de l'anode. Dans notre étude, l'aluminium et le zinc sont essentiellement sous forme dissoute dans les eaux faiblement enrichies par les métaux libérés par l'anode (conditions témoin et C1) et leur fraction particulaire devient majoritaire aux plus fortes concentrations C3 et C4.…”