Isotopic (Cu, Zn, and Pb) and elemental fingerprints of antifouling paints and their potential use for environmental forensic investigations

Antifouling paints (APs) are one of the important sources of Cu and Zn contamination in coastal environments. This study applied for the first-time a multi-isotope (Cu, Zn, and Pb) and multi-elemental characterization of different AP brands to improve their tracking in marine environments. The Cu and Zn contents of APs were shown to be remarkably high-35% and-8%, respectively. The delta 65CuAE647, delta 66ZnIRMM3702, and 206Pb/207Pb of the APs differed depending on the manufacturers and color (-0.16 to +0.36%o,-0.34 to +0.03%o, and 1.1158 to 1.2140, respectively). A PCA analysis indicates that APs, tires, and brake pads have also distinct elemental fingerprints. Combining isotopic and elemental ratios (e.g., Zn/Cu) allows to distinguish the environmental samples. Nevertheless, a first attempt to apply this approach in highly urbanized harbor areas demonstrates difficulties in source apportionments, because the sediment was chemically and isotopically homogeneous. The similarity of isotope ranges between the harbor and non-exhaust traffic emission sources suggests that most metals are highly affected by urban runoff, and that APs are not the main contributors of these metals. It is suspected that AP-borne contamination should be punctual rather than dispersed, because of APs low solubility properties. Nevertheless, this study shows that the common coastal anthropogenic sources display different elemental and isotopic fingerprints, hence the potential for isotope source tracking applications in marine en-vironments. Further study cases, combined with laboratory experiments to investigate isotope fractionation during releasing the metal sources are necessary to improve non-traditional isotope applications in environ-mental forensics.

Automated summary

This study applied a multi-isotope and multi-elemental characterization to different antifouling paints (APs) for the first time, to improve their tracking in marine environments. The high contents of copper and zinc were observed in APs. The elemental fingerprint analysis revealed that APs, tires, and brake pads have distinct fingerprints. However, the first attempt to apply this method in highly urbanized harbor areas showed difficulties in source apportionments.