According to a new study, corrosion protection on offshore installations could lead to increased concentrations of metals in seawater and the seabed.The Federal Maritime and Hydrographic Agency examined water and soil samples in cooperation with the Helmholtz Center Hereon (Geesthacht).The samples were from around wind farms in the North Sea.The research team observed isolated increased concentrations of aluminium, zinc, indium and gallium.This was announced by the Federal Office on Wednesday in Hamburg.Locally increased concentrations of lead were also found in isolated cases in the sediment.The metals are used in so-called sacrificial anodes, which prevent corrosion of the offshore steel structures, but which dissolve themselves in the process.Indium and gallium are rarely found naturally in the sea.They are therefore considered so-called tracers that reveal the origin of the emissions from the sacrificial anodes.According to current experience, 150 to 750 kilograms of the anode material get into the marine environment per year and wind turbine.The concentration of aluminium, zinc, indium and gallium was mostly within the known variability for the North Sea.The occasionally increased values ​​could possibly be traced back to certain weather conditions when the water around the offshore installations was minimally mixed.The causes of the locally increased lead concentrations have not yet been clearly identified.The Federal Office fears that the further expansion of offshore wind energy could increase emissions from corrosion protection.In the future, wind farm operators should therefore increasingly use so-called impressed current anodes, which only emit very small amounts of substances into the marine environment.According to the information, more than 1,500 wind turbines are already in operation in the North and Baltic Seas.There are also 30 transformer and converter platforms off the German coast.