AbstractOffshore wind energy is a steadily growing sector contributing to the worldwide energy production. The impact of these offshore constructions on the marine environment, however, remains unclear in many aspects. In fact, little is known about potential emissions from corrosion protection systems such as organic coatings or galvanic anodes composed of Al and Zn alloys, used to protect offshore structures. To close this gap of knowledge, the joint project “OffChEm” was initiated by the Federal Maritime and Hydrographic Agency (BSH).
The presented study focusses on the analysis of potential inorganic contaminants released from galvanic anodes that are widely used in the marine environment for the protection of such offshore structures. Those anodes are designed to corrode in place of the structural steel, resulting in the continuous emission of metals (e.g. > 250 kg Al-anode material per pile and year) into the marine environment. In order to systematically evaluate the emission load and the fate of potential contaminants (a) suitable tracers have to be identified and (b) reliable analytical methods for their detection and quantification in marine compartments need to be developed and applied.
In this study, Al and Zn anodes from several manufacturers were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) based techniques to identify suitable tracers for anode specific emissions as wells as the content of elements of environmental concern. High mass fractions of rare and/or technology- and environmentally-critical elements such as In (≤ 230 mg/kg), Ga (≤ 130 mg/kg), Cd (≤ 700 mg/kg), and Pb (≤ 20 mg/kg) were found. ICP-MS-based techniques were developed for the quantification of new tracer analytes, such as In and Ga, and applied to water, sediment and biota (Mytilidae) samples from inside and around offshore wind farms located in the German North Sea. First results of elemental concentrations in biota (Mytilidae) and spatial trends in seawater and sediment samples will be presented and discussed.