Spatial distribution of polycyclic aromatic hydrocarbons in Terminalia catappa L. (Combretaceae) bark from a selected heavy road traffic area of Rio de Janeiro City, Brazil

The levels of 21 polycyclic aromatic hydrocarbons (PAHs) with molecular weights between 128 Da (naphthalene) and 300 Da (coronene) were determined in Terminalia catappa L. (Combretaceae) bark. Tree bark samples were collected in the campus of Oswaldo Cruz Foundation, a green area located in a very intensive traffic area of Rio de Janeiro City, Brazil and about 10 km away from the city center. Samples were submitted to ultrasonic extraction with dichloromethane and analyzed by high-resolution gas chromatography-mass spectrometry. Individual PAH levels varied from 1.23 to 327 ng/g and phenanthrene, fluoranthene and pyrene predominated in all samples. Total PAH levels ranged from 242 to 1640 ng/g with a mean of 628 ng/g. The levels of total PAHs and of total carcinogenic PAHs showed not a clear dependence with tree location and distances to the main routes of that area. No correlation was observed also with PAH levels previously found in total suspended particulate thus indicating that in this area tree bark PAH levels cannot be used to assess their atmospheric levels.