Eee lale) 
A = A 
Dallium are typical tracers 
for sacrificial anodes; 
nu instruments 
Components of 
Sacrificial Anodes 
The chemical characterisation of diffe- 
rent sacrificial anodes on aluminium- 
zinc-basis showed that these contain 
up to 15 other elements for zinc anodes 
and 26 other elements for aluminium 
anodes besides their main components 
(Reese et al. 2020). The contents of 
elements largely corresponded to the 
manufacturer’s specifications. 
X 
LABORATORY STUDY 
Analysis of Trace Metals 
it was a challenge to develop a method 
for the reliable analysis of trace me- 
tals in seawater and sediment samples 
from the North Sea. On the one hand, 
the elements, which are typical for 
the corrosion protection, needed to be 
distinguished from the naturally occur- 
ing ones in the marine environment. 
On the other hand, the sample charac- 
teristics are in general complex and the 
examined elements are mostly present 
only in very low concentrations in the 
marine environment. 
The methods based on the inductively 
coupled plasma tandem mass spectro- 
metry (ICP-MS/MS) allow to quantify 
Jp to 39 elements in water samples 
and 73 elements in sediment samples - 
with the required low detection limits. 
In the area of offshore wind energy, 
mainly sacrificial anodes based on 
aluminium are used which consist of 
aluminium, zinc, and indium. Heavy 
metals such as lead, and cadmium 
which are harmful for the environment, 
were only found in very small quantities. 
In contrast, sacrificial anodes based 
on zinc, contained higher quantities of 
lead and cadmium. 
For the field studies, elements have 
been identified that fulfil at least one of 
the following criteria: (1) high quantity, 
(2) high toxicity, (3) availability of com: 
parative data or assessment criteria and 
(4) possibility to assign them to sources 
(known as tracers). 
Based on these criteria, the researchers 
selected the elements aluminium, zinc, 
indium, gallium, lead and cadmium for 
further investigations. The elements 
indium and gallium can be used as 
tracers for sacrificial anodes, as they 
rarely occur in the sea naturally and no 
other human sources are known so far 
in the open sea.