Polycyclic aromatic hydrocarbons in agricultural soils: spatial distribution, toxicity evaluation, and sustainable...

The rapid urbanization, the increased anthropogenic emissions, and the extreme flooding events caused by climate make urban floodplains more prone to contamination. Polycyclic aromatic hydrocarbons (PAHs) are a potential threat to post-flood agricultural soils in the peri-urban river basins due to their persistence and toxicity, which has not been adequately studied. This paper explores the distribution, characteristic and toxicity of PAHs in Yamuna River floodplain agricultural soils. Surface soil samples were carried out from 25 sites that had been affected by the floods using USEPA method. The mean concentration of ∑16 PAHs in agricultural soils varied between 310.93-1461.80 µg/kg, with significant spatial variance across the study area (785.97 µg/kg). Low-molecular-weight PAHs were predominant especially naphthalene and acenaphthylene which indicated combustion processes due to urban activities. Spatial analysis showed areas of contamination linked with traffic emissions and biomass burning. The pyrogenic sources were confirmed by diagnostic ratios, correlation analysis (fluoranthene-chrysene, r = 0.744), and principal component analysis. Toxic equivalency analysis revealed that high-risk PAHs contributed over 70% of the overall toxicity. The study is emphasizing the importance of climate-resilient land-use plans and post-flood soil screening programs to ensure sustainable soil management and limit contaminant transfer into crops/food webs.