Analysis of Atmospheric Air Pollutants using Lichens as a Bio-monitor by Calibration Free-Laser Induced Breakdown Spectroscopy Technique

Abstract

Biomonitoring provides information on the quality of the environment or its modification and has been used as an alternative to monitoring chemical pollutants. The lichen bio-monitoring technique and calibration Free-Laser induced Breakdown spectroscopy (CF-LIBS) were used to study trace element atmospheric deposition in five areas of Addis Ababa city. The emission of air pollutants, mainly from anthropogenic sources, has led to the degradation of air quality. The element contents of the transplanted Epiphytic lichen were determined in the vicinity of different heavy traffic and small industry places. We identified twenty-one elements (Fe, Ti, U, V, Ni, Eu, Zr, Sr, Ba, Hf, Na, K, Sc, Si, Al, Mg, Ca, C, N, O, and H). Calibration Free-Laser induced breakdown spectroscopy and semi-quantitative methods were used to calculate the concentration of pollutants to point out the most polluted areas for the chemical analysis. Dried samples of the lichen containing heavy pollutants elements like Fe, Ti, Sr, Sc, Ba, Ni, Eu, and Zn are found, and their concentration is determined. Comparison of the elemental concentration in lichen samples transplanted in 4-kilo and science faculty compound with those the Bola airport, central bus station, and Laghar train station reveals that the science faculty compound and 4-kilo areas show a considerably higher concentration of most elements in the lichen than observed in the other areas of the city where lichen samples have been transplanted. Advanced MATLAB algorithm have been used for data analysis.