Polycyclic aromatic hydrocarbons (PAHs) in surficial sediments of Vembanad wetland ecosystem, southwest coast of India: An integrated assessment of dissemination, source apportionment, ecological and public health implication

The present study assessed the dissemination, sources, ecological and human health risks of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments collected from Vembanad Lake. Total PAHs varied from 47.1 to 424.4 ng/g during monsoon and 155.9 to 749.4 ng/g during nonmonsoon, which remain below the levels found in most other sediment studies conducted globally. Strong positive correlations were found between PAHs and TOC (r = 0.457, p < 0.05), silt (r = 0.521, p < 0.01), and clay (r = 0.533, p < 0.05), suggesting that PAHs are strongly absorbed onto fine-grained particles. The origin of PAHs in Vembanad Lake is predominantly attributed to diverse anthropogenic activities, including industrial discharges, domestic sewage, port operations, vehicular emissions, oil spills, and runoff from surrounding urban and agricultural areas. Multivariate statistical analysis showed that combustion sources (coal or biomass combustion: 50.69 %), vehicular emissions (48.08 %) and petrogenic sources (1.23 %) are the main sources of PAHs. According to sediment quality assessment, acenaphthylene (Acy) in monsoon seasons exhibited occasional biological effects, while pyrene (Py) did so in the nonmonsoon seasons. Noncarcinogenic risks due to PAHs were very low (HI <1). While carcinogenic risks were moderate, BaP was found to pose significant carcinogenic risks (ILCR >10⁻³). Thus, the study area requires continuous monitoring and pollution control measurements. This study presents the first comprehensive health risk assessment of PAHs in the Vembanad wetland, offering valuable insights into potential human exposure and associated risks, and addressing a critical gap in regional environmental research.