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Figure 1. Sampling design for an NTS in the Belgian part of the North Sea (left) and the German part of the North Sea (top right). An overview of the 
'ocation of both study areas is highlighted in red in the bottom right panel. 
Polyurethane and epoxy resins are often used as top coatings 
on offshore wind turbines.'” Depending on the polymer and its 
composition, the degradation of these might introduce different 
chemicals into the surrounding environment. Leaching experi- 
ments, e.g., by Bell et al.,”° Brand et al.“ and Luft et al.” have 
provided further insights into which compounds might leach 
into the environment; however, the actual environmental 
concentration remains unknown to this point. Additionally, a 
road variety of technical formulations for coatings are 
commercially available, with only limited compositional 
information provided by producers. Therefore, chemicals are 
still being overlooked. Moreover, some of the leached 
compounds, such as diisocyanates, may degrade into diamines”” 
which are classified as carcinogens“”* and should therefore also 
ve assessed in the environment. Due to the described challenges 
and the lack of field data, it remains difficult to identify all 
organic substances that might be released from OWFs. A 
nontargeted screening (NTS) might help to identify suspect or 
even unknown (organic) chemical emissions. 
To fully assess the actual impacts of OWFSs in the marine 
environment, it is paramount to first identify the potential 
chemical contaminants leaching from OWFSs into the marine 
environment. To our knowledge, this study is the first to (i) 
provide a broad NTS for detecting organic compounds that are 
detectable by liquid chromatography (LC) and gas chromatog- 
raphy (GC) in sediment samples in and around OWFSs, (ii) 
select compounds that are more abundant in OWFSs using a 
score function that takes into account three reference areas 
ınfluenced by other human activities, such as shipping and near- 
shore activities, and (iii) tentatively identify these compounds 
using different databases. 
2. MATERIALS AND METHODS 
2.1. Sampling and Study Areas 
The Belgian and German parts of the North Sea cover a respective area 
af 3454 km” and 28,500 km”, in which a broad variety of activities take 
place, like the disposal of dredge material, fisheries, nature preservation, 
energy production, sand extraction, shipping, etc. Because of all of these 
activities, it is challenging to allocate contaminants to their respective 
source. Therefore, in this study, three different reference areas were 
zonsidered: low reference samples (low ref), which were mainly 
intended for capturing the background concentrations; ship reference 
samples (ship ref), to measure the effects of ship traffic; and high 
reference samples (high ref), which capture most of the human 
activities taking place within 12 nautical miles of the shoreline. 
Sediment samples were collected during two sampling campaigns in 
and near OWFSs (impact and nearby) and reference locations in the 
Belgian and German parts of the North Sea (Figure 1). In the Belgian 
part of the North Sea, 2 X 8 impact locations were sampled in two 
different OWFs. For each OWF, four out of the eight sampling stations 
were selected along the line of the main residual current (NE), at a 
distance of 300 (two) or 150 m (two) in either direction of a turbine. 
The other four stations were sampled perpendicular to that, again at a 
distance of 300 (two) or 150 m (two) from a turbine. Two to three 
nearby locations were selected in each main direction away from the 
OWF. 
For the reference locations, the Belgian part of the North Sea 
(BPNS) counted five low ref locations, three high ref locations, and 
three ship ref locations. In the German part of the North Sea (GPNS), 
18 impact samples were collected at six different OWFs. Nearby 
locations were collected only around four OWFs, with a total of nine 
sampling locations. For the reference locations, the GPNS counted six 
low ref locations, two high ref locations, and one ship ref location. For 
legal reasons, the locations within and near the OWFs were 
anonymised. 
[he sampling took place in April 2023 with RV Belgica (BPNS) and 
VWES Atair (GPNS). At each sampling location, two (BE) to three 
(GE) sediment samples were collected using box corers. In the BPNS, a 
NIOZ boxcorer was used with a diameter of 50 cm. For the GPNS, an 
https://doi.org/10.1021/acs.est.5c17939 
Environ. Sci. Technol. XXXX, XXX, XXX—-XXX