Analytical Method for Biomonitoring of PAH Using Leaves of Bitter Orange Trees (Citrus aurantium): a Case Study in South Spain

In this work, an analytical method for the determination of the 16 polycyclic aromatic hydrocarbons (PAHs), classified as priority pollutants by the US Environmental Protection Agency (EPA), on bitter orange leaves has been optimised and validated. The method has been applied to the evaluation of the applicability of leaves of bitter orange tree as a bioindicator of urban atmospheric pollution by these contaminants. Leaves of bitter orange trees were collected from 13 sampling points in Seville city (South of Spain). Sampling points were located in high-density traffic streets (n = 5), in low-density traffic streets (n = 5) and in urban parks (n = 3). Fourteen of the 16 PAHs monitored were detected in bitter orange leaves. The highest mean concentrations corresponded to BaA, Phen, Pyr and Flt. The concentrations in high-density traffic streets were similar to those in low-density traffic streets. Lower concentrations were found in leaves from parks. PAH diagnostic ratios were applied to identify and to assess pollution emission sources. Diagnostic ratios obtained were consistent with traffic emissions as the main source of PAH to urban air. Based on the obtained results, leaves from bitter orange trees appears to be a promising inexpensive passive sampler suitable for extensive sampling in time and space that can be applied to evaluate risk assessment of urban population to PAH air pollution.