Evaluation of the airborne pollution by emerging contaminants using bitter orange (Citrus aurantium) tree leaves as biosamplers

By Pedro José Barroso, Julia Martín, Juan Luis Santos, Irene Aparicio, and Esteban Alonso
Science of The Total Environment
July 15, 2019
DOI: 10.1016/j.scitotenv.2019.04.391

Abstract

In this work, an analytical method has been applied to biomonitor airborne emerging pollutants in urban areas using bitter orange (Citrus aurantium) tree leaves, which is an evergreen species widely extended in the Mediterranean region, as biosampler. Leaves, from trees located in 20 different locations from Seville City (South of Spain) were sampled during one year period. Sampling sites were located in six highly populated areas, in seven lowly populated areas, in six urban parks and in one industrial area. Fifteen of the target compounds were detected in the analysed samples. The highest concentrations corresponded to plasticizers (up to 852 ng/g dry matter (dm)) and surfactants (up to 752 ng/g dm), especially di(2-ethylhexyl)phthalate and nonylphenol. Spatial distribution allowed assessing the influence of populated areas in the concentration of some of the studied compounds, such as plasticizers and perfluorinated compounds, and the influence of industrial areas, in the concentration of surfactants. No clear influence of the climatic conditions (temperature, solar radiation and rainfall) on the concentrations of studied compounds was observed. This fact could be due to the presence of diffuse sources of these compounds. In the case of the brominated flame retardant, the measured concentrations could be related with two fire episodes in the vicinity, but until now it has not been possible to rigorously demonstrate a causal relationship. This fact could reveal the suitability and valuable use of Citrus aurantium tree leaves for biomonitoring atmospheric pollutants, especially from unexpected emissions in atmospheric pollution episodes.

 

Highlights

• Tree leaves were used as biosamplers of emerging contaminants (EC) in urban air.

• High concentrations of surfactants and plasticizers were found in tree leaves.

• No significant spatial and seasonal variations in concentrations were found.

• High concentrations of HBCDD were found in tree leaves located close to fire events.

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