Polycyclic aromatic hydrocarbons in diverse agricultural soils of central India: occurrence, sources, and potential risks

Abstract

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds found ubiquitously in the environment and pose serious threat to the environment and humans. PAHs have received considerable attention due to their carcinogenic properties. In this study, the 16 EPA priority PAHs were determined in agricultural surface soils (0–5 cm) from diverse agricultural land use systems in central India. ∑16 PAHs of different agricultural soil samples ranged from ND–122.52 µg/kg. Total concentration of 7 carcinogenic PAHs ranged between ND and 101.64 µg/kg. The levels of PAHs in different agricultural soil samples varied widely. In general, we observed that ∑16 PAHs concentrations in agricultural soils have followed the order: sewage irrigated soil ≥ fly ash treated agricultural soil samples > horticulture land use soil > conservation agriculture soil > organic farming soil. PAH levels in fly ash-treated soils were 2–5 times higher than that in sewage-irrigated soils. PAHs containing four to five rings were the most common. Soil organic carbon (SOC) was positively correlated with ∑16 PAHs (p < 0.05). The principal sources of PAHs in these samples according to diagnostic ratios were biomass burning (grass, wood, crop residue) and coal combustion. In addition, it was found that agricultural soils treated with fly ash and sewage irrigated soils showed higher carcinogenic potential based on B[a]Peq TEQs. PAHs with higher carcinogenic potency in these contaminated soils indicate a higher level of health risk for humans.