Ecological risk assessment of Polychlorinated Biphenyls (PCB) in the sediment around Langkawi Island, Malaysia

Abstract

Background : Langkawi Island, a UNESCO Global Geopark in Malaysia, faces increasing vulnerability to organic contamination from
persistent pollutants such as polychlorinated biphenyls (PCBs). Owing to their environmental persistence and bioaccumulative properties, PCBs pose potential ecological and human health risks, particularly in coastal and port-influenced environments.. Objective: This study aimed to determine the concentrations, spatial distribution, possible sources, and ecological risks of selected PCB congeners in surface sediments surrounding Langkawi Island. Methodology : Surface sediment samples were collected from five locations around the island and analyzed for fourteen PCB congeners. Sample preparation and extraction followed United States Environmental Protection Agency (USEPA) standard methods. Quantitative analysis was conducted using gas chromatography equipped with a micro-electron capture detector (GC-µECD). Ecological risk was assessed using established sediment quality guidelines and probabilistic risk approaches. Results : Total PCB concentrations ranged from 42.35 to 151.96 ng/g, with a mean concentration of 60.42 ± 4.31 ng/g. The highest PCB levels were observed at Telaga Harbor, likely associated with intensive maritime activities and vessel maintenance operations. No significant correlation was found between total PCB concentrations and sediment organic content, suggesting multiple or localized contamination sources. High-chlorinated PCB congeners predominated (63%), indicating inputs from port operations, jetties, and waste disposal activities. Ecological risk assessment indicated occasional adverse biological effects, while the probability of severe toxicity to aquatic organisms and risks to human health remained below 50%.. Conclusion: Although PCB contamination in Langkawi Island sediments is moderate, localized hotspots associated with harbor activities warrant attention. The dominance of highly chlorinated congeners high lights the influence of maritime-related sources. Continued environmental monitoring and management of ship-related contaminants are recommended to protect the ecological integrity of this geopark.