Regional occurrence, fate, and environmental implications of polycyclic aromatic hydrocarbon in the BIMSTEC region

This study synthesizes polycyclic aromatic hydrocarbon (PAHs) contamination across the Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation (BIMSTEC) region which includes Bangladesh, India, Bhutan, Myanmar, Nepal, Sri Lanka, and Thailand. The analysis revealed extreme spatial heterogeneity within the PAHs concentrations across environmental matrices, like the atmospheric levels ranged from 2.3 ng/m3 (Nepal) to 5,578 ng/m3 (Bangladesh). It has further been reported that aquatic contamination exhibits considerable variability, ranging from 878.7 to 47,366 ng/g in water and sediments across the study region, while urban soils exhibited concentrations between 830 and 3,880 ng/g. It has been found that biomass combustion significantly contributes to PAHs, with Bangladesh showing the highest burden in the BIMSTEC region. The research distribution further revealed significant knowledge gaps, with India contributing nearly 40% of regional studies, while lower-income countries such as Myanmar accounted around 4%. Along with it, the behavior and persistence of PAHs has been shaped by a complex interplay of physicochemical properties, meteorological conditions, seasonal variations, and the exacerbating role of climate change. Such complexity calls for in-depth research, coordinated regional efforts, and the implementation of effective mitigation measures to safeguard environmental integrity and public health in the BIMSTEC region.