Surface sediments as a sink and risk source for legacy POPs during waste management practices

Abstract

Persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are globally recognized contaminants due to their persistence, bioaccumulative properties, and toxicity. Despite regulatory efforts, these compounds continue to enter the environment through improper waste management practices, including shipbreaking activities. This study investigates the PCB and PBDE contamination of marine sediments along a 30 km coastline in Aliağa, Türkiye, involving one of the world's largest shipbreaking yards. Sixteen surface sediment samples were analyzed for 46 PCB and 23 PBDE congeners. The results revealed Σ₄₆PCBs ranging from 5.17 to 4750 ng/g and Σ₂₃PBDEs from non-detectable to 5053 ng/g. Shipbreaking activities exhibited the highest concentrations, while the sediments sampled close to beaches had the lowest POP contamination. Source apportionment using principal component analysis (PCA) identified distinct contamination patterns, associating higher-chlorinated PCBs with shipbreaking and lower-chlorinated PCBs and PBDEs with land-based industrial emissions and urban runoff. Ecological risk evaluation showed that most sediment samples exceeded sediment quality guidelines, with some PCB and PBDE congeners posing moderate to high risks to benthic ecosystems. Particularly, PCBs 28 and 52 exhibited low to high risk for almost all sediment samples. This study emphasizes the urgent need for improved waste management practices, particularly for POP-containing materials, to mitigate ecological risks. Shipbreaking yards are identified as hotspots for legacy POP contamination, necessitating international collaboration and stricter enforcement of environmental regulations as shipbreaking operations encompass cross-country transfer of wastes. Findings highlight the critical importance of remediation strategies to protect marine environments.