Anatomical, physiological, and chemical alterations in lichen (Parmotrema tinctorum (Nyl.) Hale) transplants due to air pollution in two cities of Brahmaputra Valley, India

The lichen species Parmotrema tinctorum (Nyl.) Hale was transplanted in two cities-Tezpur (small) and Guwahati (large)-of the Brahmaputra Valley to assess the impact of air pollution on the anatomy and physiology, and accumulation of pollutants. Significant damage to the anatomy was observed in samples, and the degree of damage was found to be higher in the transplants of the larger city. In the lichen transplants from locations having high traffic density, the total chlorophyll content was found to fall; on the contrary, electrical conductivity was found to be higher. The exposed-to-control ratio showed severe accumulation of Cd in all the transplants. Elements such as Cd, Pb, and Zn were found to be enriched in all the lichen samples from both Guwahati as well as Tezpur city. Besides, Cr, Cu, K, and Ni were also realized to be enhanced to a moderate extent. The correlations of indicator metal species pairs showed that anthropogenic influence was quite clear.

Automated summary

The study revealed significant anatomical damage in lichen samples transplanted in larger cities, with a decrease in chlorophyll content and an increase in electrical conductivity in samples exposed to high traffic density areas. Severe accumulation of Cd was observed in all transplants, with enrichment of elements such as Cd, Pb, and Zn in lichen samples from both cities.