Indian scientists have classified levels of atmospheric pollution using lichens.
INDIAN scientists find lichens can
be used to monitor urban pollution
levels. Lichens are disappearing
within the core zone of the highly
industrialised Haldia township in
West Bengal, due to increasing air
pollution. (Pollution Research, Vol
11, No 1).
Sensitivity of lichens - essentially symbiotic associations of fungi
and algae, often found growing on
tree trunks and rocks - to air pollution, particularly gases like sulphur
dioxide and particulate matter like
dust, is fairly well-known.
At HaIdia, effluents from companies like the Indian Oil, Eureka
Chemicals, Hindustan Fertilizer,
Shaw Wallace and Hindustan Lever
and smoke from marine vessels pollute the atmosphere.
S G Mina and S C Santra at the
School of Environmental Sciences,
University of Kalyani, and K N
Roychowdhury, of the Botanical
Survey of India, Howrah, discovered
more lichen species are present in
areas where pollution levels are low.
The scientists have drawn up an
index of atmospheric purity (IAP)
using lichens to classify levels of
pollution in various areas of Haldia.
Both the lichen constituents are
affected by gaseous and particulate
pollutants. Matter accumulates in
the tissues bringin bout degenergation and a number of morphological changes. Mitra and Santra also discovered more pollution-tolerant species, like Bacidia convexula and Parmelia caperato, are found in
areas with higher sulphur dioxide
levels, while more sensitive species
like TrypetheIium trot m and
Gyrostomum scyphiliferum are found where pollution levels are lower.
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