Environmental Science & Technology
Sompound 37
31.8N}
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As NearbyNE|
A
[owFA) 6
°
[a
51.6N1
A Pe
4 NearbySE|
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51.4N:
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\
6
51.2N-
yo
75
150
1.25
00
22E 24E 26E 28E 3.0E 3.2E 34
Zompound 9882
51 8N'
Oo
{ship Ref)
FAN
Ö
x
An A NearbyNE)
A
(ow),
°
°
3
51 6N:
A a
0
a [Neartysw A
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51.4N1
“high Ref
51.2N-
pubs.acs.org/est
Compound 346
51.8N1
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OWFA 4
°
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0
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a a
4 [|OwFB| "[NearbySE|
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51.6N:
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0,50
0.25
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51.2N}
2.2E 24E 2.6E 2.8E 3.0E 3.2E .
Compound 893
31.8N-
a
&
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Z A
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+ Q% S ©
S °
o
51.6N
BR
o
A __o En
„5 NearbySE
a [Nearbysw X
Low Ref
51.4N}
oo
75
150
125
00
531.2N-
NE
Vererrzmsgsm....= Dr E EZ.
2.2E 24E 2.6E 2.8E 3.0E 3.2E 3.4E 2.2E 24E 26E 2.8E 3.0E 3.2E 3.4E
Figure 5. Spatial distribution of the TOC normalized intensity (Ioc) rescaled between zero and one for four different compounds detected in the study
area. OWF A (green background) and B (blue background), and their corresponding nearby locations are plotted in a separate window. Compound 37
's an unidentified compound detected by GC-MS that was classified as a background compound. Compound 346 is an unidentified compound
detected with GC-MS that was classified as an impact compound for OWF B. Compound 9882 was identified as undecyl hydrogen sulfate (industrial
cleaners) detected by LC-HRMS in ESI mode and classified as a ship ref compound. Compound 893 was identified as Chrysene (PAH) detected by
GC-MS and classified as a high ref compound, indicating a source in the near-shore area.
MS, whereas no phenols were found in either GC-MS or LC-
HRMS (see Supporting Information S3).
3.5. Background and Historical Contaminants
Background and historical compounds are defined as those
detected consistently across all reference and impact areas
without a clear discernible spatial distribution (Figure 5,
compound 37). The majority of compounds detected in the
BPNS (6,483 features) and GPNS (6,271 features) fall into this
category, being omnipresent across reference, impact, and
nearby areas. These compounds are not specifically linked to
OWF activities. Instead, they likely originate from historical
contamination or diffusive sources that have, over time,
contributed to a baseline or background concentration across
:he greater North Sea. Additionally, some of these pollutants can
also have natural sources, such as heavy metals, natural oils, and
some PAHs, which can be released through natural processes
.ike rock weathering, volcanic activity, or sediment disturb-
ance.”* Other compounds may solely stem from natural sources,
such as metabolites produced by marine organisms.”®
3.6. Chemical Fingerprint of Offshore Wind Farm-Related
Areas
OWF-related chemicals are features detected in at least one
OWF with a significantly higher abundance compared with each
reference area (Figure S, compound 346). The majority of
identified compounds are not included in the list of potential
OWF chemicals emitted based on bibliographic research,”
indicating that chemical emissions from OWFs are still mostly
unknown. The low overlap between the list of potential OWF
Chemicals and this study could partly be explained by the large
number of chemical formulations and technologies available
during the construction and maintenance phase of the OWF.
For example, Hengstmann et al.'* reported that 58% of the
identified compounds were potentially released from OWF
coatings. Taking into account the wide range of available
coatings on the market, it can be expected that a majority of the
detected compounds from the NTS may be linked to the use of a
specific coating. Given that the chemical formulation of these
zoatings is rarely disclosed, many chemicals that have not been
identified in previous leaching experiments (e.g., Bell et al.?°)
nttps://doi.org/10.1021/acs.est.5c17939
Environ. Sci. Technol. XXXX, XXX, XXX—-XXX
