Lichens as Bio-Identity Tool for Monitoring Atmospheric Heavy Metal Deposition in Industrial and Urban Environment

Obiakor, M.O and Ezeonyejiaku, C.D


Heavy metal pollution has been a major concern to the society. The rate of exposure to this pollutant is alarmingly on the increase with its attendant public health risk. The aim of the study was to investigate the atmospheric deposition of heavy metals in an important semi-industrialized and sparsely populated area of Okpuno Awka, Southeastern Nigeria using lichens as biomonitor. The area being close to a traffic highway has also been on extensive differential stress of the highway rehabilitation and reconstruction for nearly five years now. Epiphytic foliose-lichens of family Parmelia were sampled from four different representative stations of various landuses covering industrial, small-scale agriculture, and urban areas (residential and roads). The lichen samples were analyzed for Hg, Pb, As, Cd, Cu, Cr, and Zn using atomic absorption spectrophotometer. Hg was not detected in all the stations observed. As was observed to be highest in concentrations compared to other metals. Appreciable quantities of some heavy metals detected in the lichens indicated atmospheric contamination. The study clearly demonstrated the effectiveness and low cost validated methodology of using lichens as biomonitor in atmospheric environmental monitoring and calls for proper implementation of environmental plans to reduce the accelerating trend of dangerous metals in the atmospheric environment. Further work is encouraged on determining the levels and distributions of heavy metals especially As, Cd, Cr, and Zn in the air as the present concentrations raise alert code.

Keywords: Foliose-epiphytes, Biomonitor, Air pollution, Bioaccumulation

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