Diversity and abundance of five species of
epiphytic lichens were assessed in Kolkata, India. Significant
correlation between abundance of lichen species and
volume of vehicular traffic suggests atmospheric pollution
load in urban region.
Parmelia caperata
(L.) Ach. and
Graphis scripta
(L.) Ach. exhibited higher abundance
among the five species studied indicating their higher level
of tolerance to air pollution. Significant correlations
(
p<0.05) between levels of heavy traffic and both diversity
and abundance of all lichen species were also
observed. These findings indicate a potential threat to the
survival of the lichen communities in Kolkata. Study further
deals with quantifying the effectiveness of lichen
species in accumulating metallic elements like Pb, Zn, and
Cu. This was achieved by analyzing the most abundant
lichen species (
Parmelia caperata) collected from nine
different sites in winter, summer, and monsoon seasons.
Metal content in lichen thalli, as analyzed by AAS, shows
their elevated levels with the order Pb>Zn>Cu. Relationship
between metal content and volume of vehicular
traffic suggests that co-associated, metallic elements are
emitted as vehicle-derived pollutants as well as diffuse
industrial emissions. Accumulation of these metals is
higher in winter which is proportionate with the higher
degree of metabolism due to higher humidity in this season.
Study also demonstrates the dynamics of metal uptake
by the lichen at different sites influenced with different
degree of vehicular traffic. Overall results confirm suitability
of lichen with their potential role in sequestration of
atmospheric metal contamination.
