Assessment and modeling of PAH levels in ambient air and vegetation: A comparative analysis of current models and proposal of a new model

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are among the important pollutant groups because of their tremendous emissions and distribution in different environmental media. This study presented comprehensive PAH concentrations from olive leaves and ambient air samples collected over one year. The average concentrations of Σ₁₂PAH in olive leaves and ambient air were 565 ± 402 ng/g DW and 22.4 ± 3.4 ng/m³, respectively. During warmer months, both leaf and ambient air samples exhibited reduced PAH concentrations. The leaf exchange is essential for understanding the accumulation of organic pollutants in trees. Some models estimate the exchange of pollutants between the air and leaves to understand their transport paths. In this study, eleven different models with various parameters were incorporated into the data. Although the octanol/air partition coefficient (K_OA) was found to be the most influential parameter in the employed models, the physical and chemical parameters of the plant, including moisture, air, and lipid content, were effective in the partition. The leaf/air partition coefficient (K_LA) was used to determine the direction of PAH movement. Calculated logK_LA values in the models ranged from 5.5 to 14. PAH compounds with log K_OA values less than 10 showed a similar trend and were close to each other for all models evaluated in this study. However, PAHs with logK_OA>10 yielded scattered results for the applied models. A best-fit model was suggested by using the data obtained in this study. The suggested model agreed well with the measured data and other models.