Comparative study of the presence of heavy metals utilizing epiphytic corticolous lichens in Talca city, Maule Region, Chile

Abstract

The concentrations of Cu, Cr, Fe, Pb and Zn in thallus of three species of epiphytic lichens were determined: Flavopunctelia flaventior, Phaeophyscia orbicularis and Ramalina ecklonii, collected in three sectors of Talca city (Region of Maule, Chile), which have been exposed to different human activities. The first collection of samples was carried out by Pereira & Tapia. in 1999 and those results were compared with samples collected in 2016. Metal determinations were made by flame atomic absorption spectroscopy, considering the thallus of each lichen as representative sample for analysis. The methodological validation was carried out using certified reference material (SRM-1570). The highest levels of concentration in the three sectors and for the two sampling periods were for Fe > Zn > Pb > Cu > Cr > Cd. In 1999, the range of concentrations of the heavy metals in dry wet varied 335.5-1724 μg/g for iron (Fe); 40.7-209.5 μg/g for zinc (Zn); 10.4-64.2 μg/g for lead (Pb); 10-28.7 μg/g for copper (Cu); 0.6-4.8 μg/g for chromium and 0.1-0.4 μg/g for cadmium (Cd) while in 2016 the ranges were 1356.6-14280.4 μg/g for iron (Fe); 26.8-179.5 μg/g for zinc (Zn); 13.5-102.5 μg/g for lead (Pb); 7.9-36.2 μg/g for copper (Cu); 3.6-24.6 μg/g for chromium and not detected for cadmium (Cd). The samples collected in 2016 generally showed higher concentration levels of Fe, Cu, Cr and Pb than those collected in 1999, especially those corresponding to the central area of the city of Talca. According to the results, the species that accumulated more heavy metals were P. orbicularis followed by F. flaventior and last R. ecklonii. It can be concluded that foliose species are potentially better candidates to be used as long-term bioindicators than the fruticose species. The downtown sector of the city is the most polluted due to the presence of tannery industries and the increase of vehicular traffic that the city has had in the last two decades as a result of agricultural development and population growth.