indium and gallium can be used as tracers
 for sacrificial anodes. They rarely
Ooccur naturally and no other human
sources are known in the open sea.

In total, four ship campaigns were conducted
 in the area of offshore wind
farms in the Exclusive Economic Zone
in the German Bight. The collected
data shows that concentrations of the
selected elements in both water and
sediment are within the range of the
known variability for the study area.

However, the researchers observed
locally elevated concentrations for the
elements indium, gallium, zinc and
aluminium in the water during certain
weather conditions. Locally elevated
concentrations were also found in the
sediment, especially for lead.

SUMMARY

Within the project “Chemical Emissions
from Offshore Wind Farms” (OffChEm),
methods have been developed to assess
 possible chemical emissions from
the corrosion protection of wind farms.
Thus, for the first time, an extensive
data set on the current situation in the
North Sea could be collected.

The research was done from 2017
to 2021 by the Federal Maritime and
Hydrographic Agency in cooperation
with the Helmholtz-Zentrum Hereon
formerly known as Helmholtz-Zentrum

Geesthacht). Trace metals in seawater
and in the sediment could then be
quantified with the help of the newly
developed methods. In the laboratory,
the researchers analysed the componNents
 of various galvanic anodes,
known as sacrificial anodes. These are
aften used as corrosion protection for
öffshore wind farms.

The researchers identified the following
alements for further investigations in
the field: aluminium, zinc, indium, gallium,
 lead and cadmium. The elements

Nevertheless, no direct effects from the
use of sacrificial anodes on the marine
environment are currently apparent
based on this data as well as the prevailing
 dilution and distribution processes.
 However, such chemical emissions
could increase further as a result of the
ongoing development of offshore wind
energy.

Therefore, the Federal Maritime and
Hydrographic Agency supports the
development and use of procedures,
which are as environmentally friendly
as possible. In the future, wind farm
projects should increasingly use impressed
 current cathodic protection
systems. These are associated with
very low chemical emissions into the
marine environment.