Accumulation of heavy metals in some species of lichens in south Tamilnadu, India.

Lichens are lower group of plants. They accumulate heavy metals and have been used as bio-indicators in pollution monitoring. Nine lichen species were collected from urban, rural and hilly areas in the southern part of Tamilnadu. Accumulation of metals differed with species and also with respect to their locations. Among the nine species, Pyxine petricola collected from urban areas showed greater accumulation of the heavy metals i.e., copper, zinc, lead, nickel, chromium and cadmium.