Microplastics as the vector for the attachment of polychlorinated biphenyls: A case study of urbanized Langat River,...

Researchers worldwide are currently facing an issue of microplastics and toxic chemical pollution in the ecosystem. Microplastics transport toxic chemicals in the ecosystem as a vector. This study investigated the occurrence and distribution of microplastics and Polychlorinated Biphenyls (PCBs) in the surface water of the Langat River, Malaysia, across six sites ranging from the open sea to riverine areas. Microplastic concentrations varied from 0.82 to 17.14 items/m³, with the highest levels observed at the station (S6), likely due to increased domestic and industrial activities. The surfaces of microplastics exhibited cracks, pitholes, particle adherence and diatom, with aluminium (Al) and potassium (K) detected via Scanning Electron Microscope/Energy Dispersive X-ray spectroscopy (SEM/EDS). Gas Chromatography-Mass Spectrometry (GC-MS) screening multiple PCB congeners on the microplastic surfaces, with PCB-28, PCB-42, PCB-101, and PCB-153 being among the most common. Environmental factors such as temperature, salinity, and pH influenced the sorption behaviour of PCBs, open sea conditions enhancing diffusion and potentially stabilizing persistent organic pollutants (POPs), while estuarine conditions impact surface charges on microplastics. The adsorption of PCBs onto microplastics, involves complex chemical and physicals mechanisms including hydrophobic interactions, π-π interactions and hydrogen-bonding, among the others. These findings emphasize the role of microplastics as substrate for co-pollutants attachment, thus the need for routine monitoring of microplastics in Malaysia and across Southeast Asia riverine.