Environmental consequences of petroleum mulch application are crucial in regions prone to wind erosion and desertification. This study aimed to assess the long-term effects of petroleum mulching on soil polycyclic aromatic hydrocarbon (PAH) concentrations and the associated human and ecological risk indices. These indices include incremental lifetime cancer risk (ILCR), hazard index (HI), toxic equivalent concentration (TEQBaP), toxic unit (TU), and risk quotient (RQ) in soil samples from Khuzestan province, Iran. Soil samples were collected from two depths: surface soil (0-10 cm) and deep soil (10-50 cm) across four regions with varying durations of petroleum mulch application: less than 5 years (T5), 5-20 years (T20), 20-30 years (T30), and 30-40 years (T40), and a control sample without mulching. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the concentrations of 19 PAHs and 23 groups of alkylated PAHs (alkyl PAHs) in the soil. Petroleum mulching significantly impacted heavily contaminated soil samples (T5 and T20) with PAH levels ranging from 2.03 to 2.08 mg kg-1. Older samples (T30 and T40) showed lower contamination levels (0.29 and 0.41 mg kg-1), primarily due to the alkylated compounds. ILCR, HI, TEQBaP, TU, and RQ indices were highest in T5 and T20 surface samples, indicating high risk in T5 surface soil from RQ and moderate risk in the others, despite low cancer and non-carcinogenic risks. Although the risk from the compounds, particularly alkyl PAHs, has decreased over time, they could still adversely affect the ecosystem, emphasizing the use of environmentally friendly alternative mulches in such areas.
Keywords: Alkylated PAHs; Desertification; Ecosystem risk; Persistent organic pollutants; Risk assessment; Soil pollution.
© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.