Tree Bark as a Bioindicator of Atmospheric Contamination by Heavy Metals according to Vehicular Traffic Intensity in El Tambo, Huancayo, Peru

Abstract

Tree bark is a good atmospheric heavy metals contamination bioindicator. This study aims to determine heavy metals in tree bark in El Tambo, Huancayo, Peru. Salix babylonica, Populus nigra, Senna multiglandulosa, and Schinus molle bark samples were taken in 2021 and analyzed through Inductively Coupled Plasma Optical Emission Spectroscopy. Results show heavy metals concentrations (mg.kg-1) of Zn (195.92 ± 125.97) > Pb (24.45 ± 15.57) > Cu (23.39 ± 11.01) > Cr (2.43 ± 1.13) > Cd (1.77 ± 3.06) > Ni (1.01 ± 0.70). The highest contamination levels were by Zn, Pb, and Cu, and the lowest by Cr, Cd, and Ni. The average concentration due to vehicular traffic intensity was Zn > Cu > Pb > Cr > Cd > Ni. Cr reveals higher concentration at high traffic levels; Cu, Ni, Pb, and Zn at moderate, and Cd at low levels. Schinus molle showed the highest concentration of Ni, Populus nigra of Cr, and Salix babylonica of Zn and Cd. The lowest concentrations of all metals were found in Senna multiglandulosa. This and Salix babylonica are bioindicators of Pb, Cr, Cd, Cu, Ni, and Zn, the first report for the world on bark in Fabaceae and Salicaceae species.